Usage of SqlDataReader.GetColumnSchema() not possible

Question

i'm trying to use the GetColumnSchema method of the SqlDataReader class. But VS tells me that SqlDataReader does not contain a definition for GetColumnSchema. Do i miss a namespace or assembly reference?

My project is using .NET Framework 4.6.1

using System;
using DocuWare.LoggingNew;
using System.Data.SqlClient;
using System.Data;
using System.Xml.Linq;
using System.Linq;
using System.IO;

private void WriteSQLQueryOutputToTextFile(string DBUser, string DBUserPassword, string sqlQuery, string databaseName, string nameOfOutputFile)
{
  StreamWriter outputFile = new StreamWriter(dWTestResult + "\\DatabaseUpgradeCheck\\" + nameOfOutputFile);           

  using (SqlConnection sqlCon = new SqlConnection("Data Source=" + GetEnvironmentVariable.MachineName + "; Initial Catalog=" + databaseName + "; User ID=" + DBUser + "; Password=" + DBUserPassword + ";"))
    {
      SqlCommand command = new SqlCommand(sqlQuery, sqlCon);
      sqlCon.Open();
      SqlDataReader reader = command.ExecuteReader();
    try
    {   
        while (reader.Read())
        {
            var columnSchema = reader.GetColumnSchema();
            string header = string.Empty;

            for (int i = 0; i < reader.FieldCount; i++)
            {
                header += $", {columnSchema[i].ColumnName}";
            }
        }
    }
    catch (Exception ex)
    {
        logger.Debug(ex, "Writing Database Output to the " + nameOfOutputFile + " file failed");
    }
    finally
    {
        reader.Close();
        outputFile.Close();
        sqlCon.Close();
    }
}

}

GetColumnSchema is an extension in System.Data.Common. Are you using System.Data.Common;? — haldo
– haldo, Commented Apr 5, 2019 at 8:13
Now, i get a "Specified method is not supported" System.NotSupportedException. Classic one :D — fabian09
– fabian09, Commented Apr 5, 2019 at 9:17

haldo · Accepted Answer · 2019-04-05 11:05:52Z

2

SqlDataReader has a property GetName() which takes an index and returns the column name.

GetName() is supported in most .Net framework (from v1.1) and .Net core (from v1.0) versions.

while (reader.Read())
{
    string header = string.Empty;

    for (int i = 0; i < reader.FieldCount; i++)
    {
        header += $", {reader.GetName(i)}";
    }
}

Or you can do it using method chaining and Linq:

// returns List<string>
var columns = Enumerable.Range(0, reader.FieldCount)
                        .Select(reader.GetName)
                        .ToList();

// columns joined on ", "
var header = string.Join(", ", columns);

edited Apr 5, 2019 at 11:05

answered Apr 5, 2019 at 10:57

haldo

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questionto42 · Accepted Answer · 2024-03-05 20:41:41Z

From SqlDataReader.GetColumnSchema Method:

Package: System.Data.SqlClient v4.8.6

You write that you have .NET Framework 4.6.1. I have the same framework and there is no 4.8.6 framework to be targeted at the time of writing. I follow the Framework targeting overview:

But if I click to install other frameworks, I do not find a 4.8.6 framework so that this high version seems to be needed only for the System.Data.SqlClient. Changing my targeted framework to 4.8 did not make the program run. I did not try 4.8.1 which you could download at the time of writing:

I doubt that it will change something.

Still, you may try the same, keep or switch the targeted framework, and then update the System.Data.SqlClient to 4.8.6.:

Uninstall and install again leads to:

Then you might get GetColumnSchema() from the Namespace: System.Data.SqlClient, but for me, it did not work. If the package version 4.8.6 is higher than the highest framework version, I do not know which framework version is needed to make it run. Any remarks are welcome. I am just a beginner at C# and the settings for .NET in Visual Studio.

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