Sqldatareader get column names. Depending on the scenario, I have also used SqlDataReader.

Sqldatareader get column names With this attribute the column name can be customized. GetOrdinal("column")). CategoryName"]; As in, ADO. TechTarget and Informa Tech’s @nawfal This approach handles the DBNull issue the OP posted about and when defined as extension methods they read better (IMHO). Rows number of SqlDataReader. Query("select * from Ride Where RiderNum = 21457"); I want to be able to do the following: When r. How do I reach a specific column of sqldatareader in C#. COLUMNS WHERE TABLE_NAME = 'vwGetData' ORDER BY Gets the value of the specified column in its native format given the column name. Name is not in the list of IDataReader - GetColumnNames. Implements. What 'length' parameter should I pass to SqlDataReader. SqlCommand query = new SqlCommand("SELECT Store. I am pulling in a Dapper FastExpando object and want to be able to reference the column names dynamically at run time rather than at design/compile time. Follow What i have tried: - Using getstring - Using index rather than column names - Specifying a specific column name - Using while (reader. Make sense? How to get data by SqlDataReader. GetOrdinal("Lastname"); Note: Not related to my question but, the real reason i want to know if a column exists, because i want to know if If the query's column has an appropriate type then. cs. C# / CSharp Tutorial; ADO. Items The problem with ordinal is if the order of the columns change and you are forced to modify the consumer code for the DataReader, unlike using column names. I'm using the following code to output query result from it: command. However, from the documentation for the IsKey column (emphasis mine):. I dont think there is a performance gain when using ordinal or column names, it is more on best practice and coding standards and code maintainability really. That is why I call it column names, because the column values I get from this table are actually column names. Dim _ExecutionResultsReader As SqlDataReader _ExecutionResultsReader = _DMTSQLCommand. As I only want to read the data from the table, using SqlDataReader would be more efficient. I want to retrieve the datatype and Size of a value from id_declarant. If so, this should work: I am a newbie and I am trying to retrieve the Column NAme , Size ( max legth ) and DataType from some table in my database , the following code when i execute it expecting it to display all the column types and names ( i didn't find how to refer to the Size , i used ColumnSize but it is said that DataColumn does not contain a definition for this method ) but when Yes Ive been able to get the table schema a couple ways to return the columns in other test scripts, but looping on the table column names and nesting or in parallel looping on the select statement with rows does not return the output that I want. Invalid cast from 'System. As an example, if you wanted to get the type of the first column you could do var firstColType = reader. And correct, a result set must have at least one column. You obtain data by reading each row from the data stream. Linq; public static class SqlDataReaderExtensions { public static int GetNthOrdinal(this SqlDataReader reader, string columnName, int nthOccurrence = 1) { // Get the schema which represents the columns in the reader DataTable schema = reader. ToString()) == 1; I then get an FormatException error, stating that "Input string was not in a correct format. Read()) { yield return reader; } } And the caller can get strongly-typed objects using: Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand; OverflowAI GenAI features for Teams; OverflowAPI Train & fine-tune LLMs; Labs The future of collective knowledge sharing; About the company Visit the blog I implemented support for the attributes NotMapped and Column used also by the entity framework. GetDateTime(MyReader. StoreID" + " LEFT The SqlDataReader. I have got this code which reads data from SQL DB. My problem is that I am trying to fill a multi-dimensional array with the first row being the column header You can use OdbcDataReader. I have sql query in my asp. The zero-based column ordinal. GetFieldType(0); The column name is in the first column of every row. Devart. Get column name from SQL Server. COLUMNS WHERE TABLE_CATALOG = '{0}' AND TABLE_SCHEMA = '{1}' AND TABLE_NAME = '{2}' AND You're missing basic C# syntax. I have a table which has 23 columns. Each column of this table describe a particular information extracted by the metadata relative to the query field Thanks, can you advice how to get COLUMN NAME from data reader also. I have seen on MSDN - DBNull. GetName to get the column name. OLEDB. For debugging purposes you can add the following line after you create the reader to get the names of the fields, which will be returned (statement taken from this answer): var columns = Enumerable. So, where in VB. Then, I want to do something like this: I need to find at run time, based on the result set represented by SqlDataReader, to find the name of the table for each column. How to get table name of a column from SqlDataReader. CSV file the way that they appear in the database which is not ideal. e. ASH ASH. Conversely, there is a GetOrdinal which takes in a column name and returns the column index. Name as StoreName," + "Product. GetString(0); //The 0 stands for "the 0'th column", so the first column of the result. Use column name to index data: 7. GetName(i) I want to be able to do something like . Gets the column names in this collection. int customerID = reader. GetSchemaTable(): It returns a System. One alternative is to use FieldCount property of datareader as given in Get number of columns in SqlDataReader based on Sam Holder's answer, you could make an extension method for that. ) instead of by name. Possible errors are: Column is not DateTime, thus GetDateTime doesn't work at all; firstMove is not a valid column name at all, so you can not access that column; Assuming the column really exists and is of type DateTime I tend to use the following: You can get the Schema Table from your SqlDataReader dr to get the column names, save the names to a List<string> and add them as columns on a new DataTable, then fill that DataTable using indexing on dr with the names from the list: DataSet ds = new DataSet(); DataTable dtSchema = dr. GetSchemaTable returns a data table with column information - but all the I don't think there's a NULL column value, when rows are returned within a datareader using the column name. I do not want to alter the query itself (changing the names to have spaces) because this query is called in another My question is how to get the number of rows returned by a query using SqlDataReader in C#. Fastest method for SQL Server inserts, updates, selects. GetSchemaTable in this case. how to read column values as C# types using the Get* methods: 4. DataTable (or DataColumn, or DataSet, or DataRow) is a generic . fetchall()) use the GetOrdinal() from DataReader to get the numeric positions of a column: 3. The example above uses a string indexer, where the string is the SqlDataReader Get Value By Column Name (Not Ordinal Number) in C#; Verify that a column exists in the DataRow before reading its value in C#; DataRow: Select cell value by a given column name in C#. 109. CommandText = "SELECT a,b,c,d FROM testTable"; AdsDataReader reader = cmd. public static void Main() { string sql = "SELECT 1 AS IntColumn, 'FizzBuzz' AS The provided answer demonstrates a good understanding of the original user's question and offers a complete solution using SqlDataReader. NET that determines whether or not a SQL server database table contains an identity column and, if so, to return the name of that column. The following example demonstrates how to use the GetOrdinal method. Name, the runtime is saying that "r. I found the solution to get the column names without having any record in the resulting relation from the sql statment: public async Task<List<string @ChristopherPisz If it was a different port then the connection string as shown wouldn't connect to it. The same syntactical from pandas import DataFrame import pyodbc cnxn = pyodbc. This method returns a DataTable object that contains information about the columns in the GetName(int i): It gets the name of the specified column. I also update client's data base and entity data model. Example while (dataReader. {2}", reader[0], reader[1], reader[2]); listBox2. cursor() query = ("SELECT `name`, `ftp_name`, `created_at`, `status` AS `status_customer` FROM `customers" "WHERE `status` = %(status)s") cursor. The query below gets all the columns for a user table of a given name: Since you are using C#, it's probably easier to obtain the names from the SqlDataReader instance that is returned by ExecuteReader. If so, this should work: The name specified is not a valid column name. Read() Dim i As Integer For i = 0 To reader. I need for PowerShell to be able to get the column names. The table names are Store, Product, StockRequest, StoreInventory. Try it. Get data from SqlDataReader by Data type: 6. I want to retrieve data by column from DataReader. The example above uses a string indexer, where the string is the column name from the SQL query (the table column name if you used an asterisk, *. With this solution I am able to get only base table names and columns but not the view names. DataTable that describes the column metadata of the The example above uses a string indexer, where the string is the column name from the SQL query (the table column name if you used an asterisk, *. NET Core. GetSchemaTable returns a data table with column information - but all the SqlDataReader. extensions { public static class AdonetExt { public static int GetInt32(this SqlDataReader reader, string columnName) { return reader. SqlClient; class Program { static void Main() { string str = "Data Source=(local);Initial Catalog=Northwind;" + "Integrated Security=SSPI"; ReadGetOrdinal(str); } private static void ReadGetOrdinal(string connectionString) { string queryString = "SELECT reader. the number of columns is unkown. select * will return all the columns from a table. At least fix your code to: using System; using System. reader. 0; Gets the name of the column, given the zero-based column ordinal. From there it is easy to track down why the column name did not exist. But I'm confused why datareader doesn't add table name before columns. Currently I am using a try. ExecuteReader() reader. Asynchronously returns a System. I would use the following and wouldn't worry too much: Use SqlDataReader. SqlDataReader displaying like fields. SELECT DATA_TYPE, CHARACTER_MAXIMUM_LENGTH FROM INFORMATION_SCHEMA. If the database changes (which is actually extremely unlikely in this case) the code breaks. FieldCount I'm trying to write some generic code in VB. DataTable dt = reader. I have a table with 3 columns in order: ID, Dir, Email. I have created 2 sample methods: Try the query below. The only robust way is to use AS in the SQL-query to make sure your column names/aliases are unique otherwise you would to access the fields by index (0 / 1 / 2 etc. Right now the data for both of the 'Name' columns are taken from the Store table. Replace the shop by your table name and id by your column name. Enumerate SqlDataReader Columns. GetSchemaTable(); DataTable dt = new DataTable(); List It's generally a good practice to have your model properties match your column names. SqlDataReader. ToString() = "x" Then Dim columnName As String = [THIS IS WHAT I WANT] End If Next The fact you're getting an exception would be easier to solve if you told us what kind of exception you get. Columns(i). Open(); SqlCommand oCmd = new SqlCommand(sSQL, GetDataTypeName(int i): Gets the name of the data type of the specified column. columns where table_name = 'shop' -- enter table name only, do But it feels very unstable. Employee Table Metadata I'm not worried about data types, just column names. If you do datareader["columnName"]. I have a SqlDataReader reader, where I don't know the data structure in advance, i. Then you can just return the value from inside the if statement, and doesn't have to store it in a variable until you have closed the objects. ColumnName i += 1 Next References. Name" because when evaluating, the reader is simply returning two columns, both just named "Name" So when searching for r. NET will throw an IndexOutOfRange exception. How to get number of rows using SqlDataReader in C#. ID and b. How to get the DataType and Size of a column using the SqlDataReader? 1. Here's the situation: First I build the structure Of grid (structure is in the table in database that was filled based on the output of a stored procedure in the system in the past) Note: Not related to my question but, the real reason i want to know if a column exists is because i want to get the ordinal position of a column, without throwing an exception if the column doesn't exist: int columnOrdinal = reader. SqlDataReader. But GetValue() can be used to retrieve any data type value. I'd like to put the table in csv file. Read()) { var value = dataReader. You will need one or more of the following medthods: GetFieldType(int) - returns the Type of the column. I can't figure out why it doesnt work here (code above) aswell. Commented Apr 8, 2012 at 18:51. Value Field that this check is rarely used. We may have properties of the class that are not data elements in the query. I am unable to take the 'Name' data from the Product table. GetOrdinal performs a case-sensitive lookup first. (+1). 20. using Microsoft. GetName returns the column name but not the table name. 26. We can see GetOrdinal sourcecode from SqlDataReader it will return a index from _fieldNameLookup. I need something like this: DataReader Column Description; ColumnName: The name of the column; this might not be unique. Parse(sqlDataReader["IsConfirmed"]. Properties decorated with this attribute will be ignored by the mapper. CommandText = "SELECT * FROM devices WHERE device_level='" + ACCESS_LVL + "'" + "ORDER BY device_name"; reader = The read-only column schema collection). Is there an equivalent to SqlDataReader's GetInt32, GetString, GetDecimal, that takes a column name instead of an index? What's considered best practice in this case? What's fastest? Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand; OverflowAI GenAI features for Teams; OverflowAPI Train & fine-tune LLMs; Labs The future of collective knowledge sharing; About the company I agree Enumerate is a better name. ToString(myDateFormat) If the query's column is actually a string then see other answers. GetBytes() 0. 4k 15 15 This article shows three ways to retrieve database column names from DataSet and DataReader in ADO. Column Attribute. You should read the linked documentation if you plan to rely on this method. IsDBNull the best/most efficient way to check for nulls?. Thanks in advance. But your loop is incorrect if you only want the column names: If you use indexes like reader. Format data when reading the data from SqlDataReader: 4. 3k 25 25 gold badges 111 111 silver badges 240 240 bronze badges. I want to fill table with these data. Rows For Each cell In row. Data = reader; // You cant do this. Without this attribute the property name is assumed to be the column name. Reference data in SqlDataReader by column name: 7. read column values as Sql* types using the GetSql* methods: 5. These are the top rated real world C# (CSharp) examples of System. You should use parameterised queries, instead of concatenating values There is a GetName function on the SqlDataReader which accepts the column index and returns the name of the column. GetSchemaTable. I retrieve the columns from. HasRows instead of FieldCount (I probably use HasRows more often than FieldCount). if it is because entity type configured incorrect column name then in the SQL you can see which table is trying to pull incorrect column and go to entity The following generic extension method(s) encapsulates checking if a column is null with SqlDataReader. and s. IsDBNull() C# (CSharp) System. You can use methods such as GetString() to get a column value converted to its primitive type. Is datareader quicker than dataset when populating a datatable? 17. . I know your actual column names are in there, but I was going down the wrong path. connector. If the column name cannot be determined, a null value is returned. NET you would use SQLdr("codigo") to access the value of the column by name, in C# the equivalent would be SQLdr["codigo"]. Net; Column Type Name; Can you get the column names from a SqlDataReader? 103. For composite foreign keys <foreign key property name> becomes an underscore separated I need to find at run time, based on the result set represented by SqlDataReader, to find the name of the table for each column. This method is an implementation of IDbColumnSchemaGenerator. So you have to pass column number instead of column name to get the value. I have used this method during the login section and it works perfectly there (code below). After executing the query, I will store the result in SqlDataReader as it has multiple columns as output. SqlDataReader only implements these Get methods that read columns by ordinal number – such as GetString(int i). DataTable that describes the column metadata of the DataReader. In fact in my personal "common" library, I've now replaced the above by an extension method on IDataReader: public static IEnumerable<IDataRecord> Enumerate(this IDataReader reader) { while (reader. Thanks! sql-server; sql-server-2008-r2; sql-server-2016; Share. Examples. GetBoolean extracted from open source projects. SqlServer Namespace / SqlDataReader Class / GetName Method. How exactly did you verify that there were 6 columns? This class of issue is almost always caused by the big three - So it is connected to the wrong database. ID), but the source table/subquery aliases are lost. public static IEnumerable<string> GetColumnNames(this IDataReader reader) { for(int i=0; i<reader. bool isConfirmed = int. Count of number of columns using SQL 使用SqlDataReader. Description: An Gets the name of the specified column. GetInt32(reader. GetSqlString(column), and since I don't know the name of the column the user may have selected, I can't do datareader. ColumnOrdinal: The zero-based ordinal of the column. GetSchemaTable(); // Find all Execute multiple SELECT statements using a SqlCommand object and read the results using a SqlDataReader object: 2. NotMapped Attribute. Gets the value of the specified column in its native format given the column name. Using the methods of the SqlDataReader, I can get the value of a column by passing in it's ordinal, such as the value of the first column if I pass in read. SELECT COLUMN_NAME FROM INFORMATION_SCHEMA. Out of the things you're doing here, looping is the least inefficient part. ExecuteReader() While _ExecutionResultsReader. 32. SqlClient. I don't know how should I edit it so I can use original column name and not column index. Then you're focusing on entirely the wrong problem. ) You'll need to change your method's return type to int as well, of course - or call ToString if you really want the value as a string. Text; I then try to get the value of a column, called IsConfirmed (which is represented as a bit type column in the database) and convert it to bool. – CuriousOne. how to read column values as C# types using the Get* methods: 5. ToString(); it will always give you a value that can be a empty string (String. GetOrdinal(string) will get the column ordinal, given the name of the column. GetOrdinal(columnName)); } } } This article shows three ways to retrieve database column names from DataSet and DataReader in ADO. CreateCommand(); cmd. System. Net « C# / CSharp Tutorial. But errors appears. For Each row As DataRow In dt. Commented Nov 8, 2013 at 6:26. You need to provide also the database-name + schema-name + table-name: string table = string. this means that provided you used a . * from a, b, then the selected columns will include two ID columns (a. RecordsAffected Gets the number of rows changed, inserted, or deleted by execution of the When you execute a SQL query and read the results with SqlDataReader, you have two options for getting column values by name (instead of by ordinal number): Use the indexer How to get the column names from a SqlDataReader in C#? Here’s a code snippet demonstrating how to do it. Quantity, StoreInventory. executedatareadet(); For example after data reader is returned I have two columns (A,B). What I'd like to do is look up a column from a DataTable schema using the column name and then get the datatype of that column. ExecuteReader()) { // This will return false - we don't care, we just want to make sure the schema table is there. Thus, is the reader. NET uses parenthesis to access the default property of an object, whereas C# uses square brackets to access the indexer property (indexers are essentially the C# equivalent of VB's default properties). Hot Network Questions What's wrong with my formal translation of "every positive number has exactly two square roots"? Would it be possible to use a Cygnus resupply i am trying to get the data type of each column given to do some verification i already tried the getSchemaTable but it only gives me the schema of a table without values. Here is The code : You can use SqlDataReader. So I am trying to get the column values from the @TableName table. GetBoolean - 42 examples found. My problem is that I am trying to fill a multi-dimensional array with the first row being the column header Your code is bad from a security perspective. GetSchemaTable to get information about the columns for the current result set (I think - the documentation isn't clear about whether or not it supports multiple result sets). NET Framework中用于读取数据的一个重要类，它提供了一种简单、有效的方式来从数据库中检索数据。 阅读更多：SQL 教程 SqlDataReader简介 SqlDataReader是ADO. I just one way to change the column name of the data reader. How can I capture this, because i want to generate a HTML table from the rows/columns returned. You should use using blocks, so that you are sure that the connection, command and reader are closed correctly. ExecuteReader(); // Call GetOrdinal and assign value to variable. Depending on the scenario, I have also used SqlDataReader. public override Task<DataTable?> GetSchemaTableAsync(CancellationToken Most of the metadata for a query results is available in the DataTable returned by DataReader. catch approach as shown below which is not efficient. GetValue by column name. Home; C# / CSharp Tutorial; Language Basics; Data Type; Operator; Statement; String; struct; Get table schema from SqlDataReader : Column Type Name « ADO. GetName). Name" or "s. Home; Tutorial. Since I don't know the datatype, I can't do datareader. Any ideas on how to retrieve the values from the database without knowing either the datatype or the column name? Thanks in You can use the query below to get the column names for your table. Data. You can easily find out if the column exists in the SqlDataReader object as shown in the code snippet. Improve this answer. Select(reader. Here are some thing that don't work: SqlDataReader. GetName(i); } SqlDataReader Get Value By Column Name (Not Ordinal Number) 0. Read data from SqlDataReader: 6. Count) As String Dim i As Integer = 0 For Each column As DataColumn In DT. Every row in datareader contains 10 columns. NET. NET Connector for SQL Server, MySQL, Access, PostgreSQL or anything else, the DataTable and DataColumn This kind of information is available through the call GetSchemaTable. There is a GetName function on the SqlDataReader which accepts the column index and returns the name of the column. SqlClient or should I do the mapping myself? I can get a string representation back from . If I load the data via an adaptor class into a datatable, I can access the field names by something like DataTab. I'm looping through a DataTable like this. Follow asked Nov 20, 2019 at 21:14. Use A Data Reader: 8. read column values as Sql* types using the SqlDataReader Get Value By Column Name (Not Ordinal Number) 0. SQLDataReader Row Count. This line is asking for an Sql Injection: SqlStr = "Select * from TB_User where UserID=" + Label1. Follow answered Jul 10, 2013 at 11:48. More worrying is that you're converting from a double to string and then back to double. This one is not working: Get the FieldCount (number of columns in the result set) and then loop through the fields (columns) in each row of the DataReader retrieving the data. the least-janky solution is to use SQL CLR. Im ultimately using this script to create a json data output and am using this script as an example. Get info about each column: Name, Ordinal and FieldType: 5. dotConnect for SQL Server Documentation. GetString(0) will it use the first column you selected in your query or the firstt column on the table. SetName(i) I have Visual Studio 2013 Ultimate and creating application of WPF. execute(query, { 'status': 1 }) # SqlDataReader objects allow you to read data in a fast forward-only manner. VB. Because ordinal-based lookups are more efficient than named lookups, it is inefficient to call GetOrdinal within a loop. Or it is connected to the right database but the database has two tables with the same name. C# SQLDataReader accessing by column name. Nullable`1[[System. To add some value to the answers, I included a possible extension method to return the column names for a given DataReader. I have SqlDataReader that gets returned from a ExecuteDataReader statement. From there if you want to refer to them by other names you can map them to a DTO or domain object with the names you want, but you'll have an easier I think that it your are searching for. namespace adonet. GetOrdinal() accepts index no of the column as well as Column Name as column reference which is a advantage of using this method from my point of view. GetValue按列名获取数据 在本文中，我们将介绍如何使用SqlDataReader. However, this does work: String categoryName = sqlDataReader["CategoryName"]; That is, you can refer to the column name without its table qualifier, even though the original query did include the table qualifiers. GetSchemaTable will return a lot of information about the columns, including their name but also size, type, etc. GetOrdinal is kana-width insensitive. Let's see if we can do better with a simple extension method. However, for best performance, the DataReader provides a series of methods that allow you to access column values in their native data types (GetDateTime, GetDouble, GetGuid, GetInt32, and so on). ItemArray columnCount = columnCount + 1 If cell. However, I have no idea, how to loop through columns in datareader. In particular, note the following: The . Strange Behavior with SqlDataReader and long columns. Get<Datatype> functions used to retrieve specific DataType values from DataReader. If it fails, a second case-insensitive search is made. Get the ID of the column being read in SqlDataReader. Text; This is how to retrieve a Column Name from a DataColumn: MyDataTable. Name is selected into the DataReader, it reads only the field name - Name. // Now we specify the Table_Name and Column_Name of the columns what we want to get schema information. Read to read result set: 2. SQL Server and SqlDataReader. Save time by calling GetOrdinal once and assigning the results to an integer variable for use within the loop. {1}. cnx = mysql. You only have to open the connection once. GetSchemaTable including columns ColumnName, BaseColumnName and BaseTableName. I then try to get the value of a column, called IsConfirmed (which is represented as a bit type column in the database) and convert it to bool. GetOrdinal(string name): Returns the zero-based column ordinal given the column’s name. My connection string for excel is connectionString = "Provider=Microsoft. GetOrdinal (_fieldNameLookup field is a FieldNameLookup class) _fieldNames is a hashtable stores the index, match via case-sensitive You could use alias to give a different name to the duplicate column. net webapp and the result is stored in datareader. use the GetOrdinal() from DataReader to get the numeric positions of a column: 4. 4. Using SqlDataReader. GetString() method accepts only parameter with int type. IsDBNull() and uses the generic SqlDataReader. In the code below, reader is a SqlDataReader and command is a SqlCommand object. It returns a DataTable where you have a row for each column returned by the query. g. In CLR you get a SqlDataReader that you can use to examine the resultset shape. FieldCount). GetValue(0), or the second String sSQL = "select id, firstname, lastname from Employee"; SqlConnection oConn = new SqlConnection(sConn); oConn. This name always reflects the most recent naming of the column in the current view or command text. My question is how to get the number of rows returned by a query using SqlDataReader in C#. ExecuteReader(); var columnnames = Yes, you can get the column names from a SqlDataReader using the GetSchemaTable() method. SqlDataReader reader = cmd. It might seem that you can, using the IsKey column value, which should return true for anything that contributes to uniquely identifying the record in the table. Columns() after it. One of the simplest solution is to navigate to all the fields within the data reader and check the name of the field using the GetName method as shown below. GetName(i); } Also you can create an extension method like below: Do you want to check if a column exists in a SqlDataReader instance in C# ?. Using DataTable in . ExecuteReader( Probably aliases is the answer. Format("{0}. 1. It returns the System. true : The column is one of a set of I'm not worried about data types, just column names. *, b. And Locally it's work fine. TechTarget and Informa Tech’s Is the best method to Retrieve data from DataReader. Get table schema from SqlDataReader : Column Type Name « ADO. Just edited my question with your comment question. GetOrdinal(columnName)). SqlClient SqlDataReader. Here, parameter i is the zero-based column ordinal. I have a query that gets report data via a SqlDataReader and sends the SqlDataReader to a method that exports the content out to a . Now I'm using like this, AdsCommand cmd = conn. The issue with caching the result of GetOrdinal applies to using reader["field_a"] as well, but this is often a micro-optimisation when reading through large datasets, and for me the improved readability trumps using a cast and The first step in our function is to get the list of columns that are in our SqlDataReader input parameter. Follow answered Nov 27, 2017 at 3:03. 6. public override string GetName(int ordinal) Parameters ordinal int. Int32, mscorlib]] 11. This column cannot contain a null There is nothing in the call to GetSchemaTable on SqlConnection which will allow you to figure this out. //Your custom code here } UPDATE Why don't you place all the values read from the DataReader , into a list, and you can use this list afterwards for comparison between values if you need it. Now assuming you know how to set up a DataReader you would do the following: using(var reader = command. is There a Column Count Property in VB. Sometimes, if data exists, I can read data u The SqlDataReader. so you still know what columns you are returning. var slqreaderobj = cmd. Improve this question. I'd be gathering the actual data type from the main table rather than the view in this case. GetString but only reader. Remember that a returned column might be String[] columnRestrictions = new String[4]; // For the array, 0-member represents Catalog; 1-member represents Schema; // 2-member represents Table Name; 3-member represents Column Name. e. After connecting to the database, can I get the name of all the columns that were returned in my SqlDataReader? I want to write a routine that loads a table (or query) and outputs it to a text file, with the field names in the first row. If selecting from more than one table or subquery with aliases a and b like select a. ToList(); So you can check if PARAMETER_NAME and PARAMETER_VALUE will be returned as expected My data source is a SqlDataReader object that contains the results of a stored proc call. You can read the columns by ordinal number (0-based index) or by name. (I'd strongly advise against it I can enumerate the results and list the values. How to read the column SqlDataReader. The code initializes a two-dimensional array for storing column headers and data, retrieves column names, and populates the array with both header information and row data. You have to access the individual table that is within the DataSet to retrieve the values. ExecuteReader(); Now I want to convert the result for each row into byte[]. StoreID = Store. ) It can't find "r. Invalid column name 'DateofBirth'. From there if you want to refer to them by other names you can map them to a DTO or domain object with the names you want, but you'll have an easier time if your model properties are 1:1 with your column names when you go to serialize them with Dapper. What I need to be able to do though is also enumerate the field names that come back from the sproc. From SqlDataReader get Column Name: 3. Follow I have a DataTable that I'm parsing through and I'm trying to find the column name of a given column when its value = "x". I presume you want the key of the dictionary to be the column name, and the value to be the row value. I have to read the data from a SQL Server stored procedure by using SqlDataReader. GetSchemaTable(). But yes, a do {} while() is a far better (and cleaner) approach than the convoluted, and less flexible, approach shown in the accepted answer. GetOrdinal("CustomerID"); // Use variable with GetString inside of loop. sqlDataReader reader; reader. connect(databasez) cursor. – Conrad Jagger. Type of the field. Read) - Requesting different number of columns. FieldCount; i++) yield return reader. String indexers are much more readable . By convention, foreign key constraints are named FK_<dependent type name>_<principal type name>_<foreign key property name>. These custom attributes are basically present to allow us to have different property names and column names (EmployeeID property populated from Employee_ID Imports System Imports System. You cannot because System. GetColumnSchema() Remarks. string query = &quot;SELECT * FROM zajezd WHERE event='& Speed is somewhat of a concern I suppose. I don't think that it's possible to omit the other column informations like ColumnOrdinal,ColumnSize,NumericPrecision and so on since you cannot use reader. NET Framework Data Provider for ODBC Your code is bad from a security perspective. notsupported. Geting varchar width of a column that is actually used. Data Imports System. GetDataTypeName(int) - returns the Name of the back-end database column type. String categoryName = sqlDataReader["Categories. From sql I need to get columns, tables and views names. 0. CSV file; however, the column names are showing up in the . Read() emailBody = emailBody + SqlDataReader objects allow you to read data in a fast forward-only manner. ColumnName To get the name of all DataColumns within your DataTable: Dim name(DT. Andrey Gordeev Andrey Gordeev. Share. for (int i = 0; i < reader. – Eadel. Open(); obj = cmd. What is the best way of handling trying to get data from a DataReader that has more than one column with the same name? Because of the amount of work involved and because we don't want to lose support from a vendor by changing the stored procedures we are using to retrieve the data, I am trying to find another way to get access to a column that shows up more than once The @TableName parameter contains the name of the table that I want to retrieve column names from. 5. Rows[0 You can access each column of the returned row by passing the name or ordinal number of the column to the DataReader. I want to change column 'A' to 'a' (convert to lower case) before binding it to the grid like reader. See MSDN for more info. StockLevel from Store" + " LEFT JOIN StoreInventory ON StoreInventory. All I want is: change some column name in the data reader, just before binding to grid. // If you simply assign reader object itself as the data you wont be // able to get data once the reader or connection is closed. The way I am doing it right now is by using a while loop and reading values from the item property like so : Recently i add DateofBirth to a table . SqlClient public class MainClass Shared Sub Main() Dim thisConnection As New SqlConnection("server=(local)\SQLEXPRESS;" & _ "integrated security=sspi;database=MyDatabase") 'Sql Query 1 Dim sql As String ="SELECT FirstName, LastName FROM Employee; "'Create Command object Dim thisCommand As I want to retrieve decimal values from the database and I would like to know which is the recommended way to check for null values. (Here the 0 is "the ordinal of the EmployeeId column; you can use GetOrdinal to get the ordinal for a named column. Columns name(i) = column. It's generally a good practice to have your model properties match your column names. For example , i have a table in my database and a columnname : id_declarant. GetColumnSchema() method, which enables the use of the IDbColumnSchemaGenerator interface to populate the DbColumn schema metadata without using a DataTable. From which you can interpret the column names by using a SqlCommand and DataReader. Can you get the column names from a SqlDataReader? Related. GetFieldValue method uses generics to return the value of a column as the requested data type, which is nice, but it also requires us to know and pass the column index instead of just using its name, which is less nice. GetString(datareader. Data; using System. You can rate examples to help us improve the quality of examples. So I want to be able to do the following: var testdata = conn. String indexers are much more readable, making the code easier to maintain. I will not know these field names at design time. ". Columns. How to check for the column name in an SqlDataReader Object in C# ? public static bool IsColumnExists Suppose I have POCO entities being read from a database and they each have "ID" as their primary key column name. Data I am facing 2 issues in OLEDB query (Problem 1) I need to get the column names of user uploaded excel sheet. I want to know if there's a way I need to read each column value and concatenate with the resultVal. Jet. NET for data access , there are times when you want to check to see if a column exists in a SqlDataReader object. The details of the table are provider dependent, for SQL Server it is documented in SqlDataReader. connect(user=DB_USER, password=DB_USER_PASSWORD, host=DB_HOST, database=DB_NAME) cursor = cnx. Read column by name with Get extension methods. This reference helped clear things up a bit, but I'm still not sure if there's an elegant way of doing it. You have to loop the reader to get the values from it. To select a cell value by a given column name in C#, you can use the DataRow's Item property or the Field extension method. Int32' to 'System. SqlCommand cmd = new SqlCommand("select leave_details from LeaveTable"); SqlDataReader obj; con. GetValue方法按列名获取数据。SqlDataReader是. StoreID, "Store. Item[Int32] Gets the value of the specified column in its native format given the column ordinal. Item[String] Source: System. . Get column index from SqlDataReader: 3. NET data container which works the same way regardless on the specific database engine you loaded your data from. Appears I stand corrected. var dateString = MyReader. execute("""SELECT ID, NAME AS Nickname, ADDRESS AS Residence FROM tablez""") DF = DataFrame(cursor. Name as ProductName," + " StockRequest. When selecting the fields, it doesn't include the table specifiers (r. For me reader. Columns(1). How to Check for Column Name in SqlDataReader object in C# ? Examples. GetFieldValue() to read the value. GetSchemaTable(); So I have them in dt. net like MS Access? 1. Adapted from the above link, you could get a list of all of your columns with the following: List<string> myCols = new List<string>(); DataTable schema = is there a class that can do that in System. I'm working in Visual Basic 2008 Express and have created a SQL database, "MyDatabase" with 1 table called "MyTable". Commented Aug 14, 2017 at 15:21. SqlClient; using System. Hot Network Questions Question on the concept of the Big Bang Theory Nonograms You can use the GetFieldType method, passing in the ordinal of the column whose type you wish to retrieve. I've seen some answers about this but none were clearly defined except for one that states to do a while loop with Read() method and increment a counter. Must have read your mind ;-) Enumerate SqlDataReader Columns. The class provides a property FieldCount, for the number of columns When working in ADO. FieldCount; i++) { string columnName = reader. ExecuteReader(); SqlDbType type = (SqlDbType)(int)reader. SqlDataReader reader = command. ColumnName. Range(0, reader. 3. DECLARE @maxRowSize int SET @maxRowSize = ( SELECT SUM(DataSize) AS MaxRowSize FROM ( SELECT COLUMN_NAME, DATALENGTH(COLUMN_NAME) as DataSize from information_schema. However I will not know the number of columns present in the query result beforehand. Empty if you need to compare). Try Dim reader As SqlDataReader = cmd. 10. the table you are using is a permanent table or temp table? – Kashif Qureshi. oqormu johlcsr nocqdg rhdjexl hwrvl nou cri ymm ddmsjsf vhra