How to run multiple SQL commands in a single SQL connection?

Question

I am creating a project in which I need to run 2-3 SQL commands in a single SQL connection. Here is the code I have written:

SqlConnection con = new SqlConn         


        

Answer 1

Just change the SqlCommand.CommandText instead of creating a new SqlCommand every time. There is no need to close and reopen the connection.

// Create the first command and execute
var command = new SqlCommand("<SQL Command>", myConnection);
var reader = command.ExecuteReader();

// Change the SQL Command and execute
command.CommandText = "<New SQL Command>";
command.ExecuteNonQuery();

Answer 2

Here you can find Postgre example, this code run multiple sql commands (update 2 columns) within single SQL connection

public static class SQLTest
    {
        public static void NpgsqlCommand()
        {
            using (NpgsqlConnection connection = new NpgsqlConnection("Server = ; Port = ; User Id = ; " + "Password = ; Database = ;"))
            {
                NpgsqlCommand command1 = new NpgsqlCommand("update xy set xw = 'a' WHERE aa='bb'", connection);
                NpgsqlCommand command2 = new NpgsqlCommand("update xy set xw = 'b' where bb = 'cc'", connection);
                command1.Connection.Open();
                command1.ExecuteNonQuery();
                command2.ExecuteNonQuery();
                command2.Connection.Close();
            }
        }
    }

Answer 3

The following should work. Keep single connection open all time, and just create new commands and execute them.

using (SqlConnection connection = new SqlConnection(connectionString))
{
    connection.Open();
    using (SqlCommand command1 = new SqlCommand(commandText1, connection))
    {
    }
    using (SqlCommand command2 = new SqlCommand(commandText2, connection))
    {
    }
    // etc
}

Answer 4

This is likely to be attacked via SQL injection by the way. It'd be worth while reading up on that and adjusting your queries accordingly.

Maybe look at even creating a stored proc for this and using something like sp_executesql which can provide some protection against this when dynamic sql is a requirement (ie. unknown table names etc). For more info, check out this link.

Answer 5

using (var connection = new SqlConnection("Enter Your Connection String"))
    {
        connection.Open();
    
        using (var command = connection.CreateCommand())
        {
            command.CommandText = "Enter the First Command Here";
            command.ExecuteNonQuery();
    
            command.CommandText = "Enter Second Comand Here";
            command.ExecuteNonQuery();

    //Similarly You can Add Multiple
        }
    }

Answer 6

Multiple Non-query example if anyone is interested.

using (OdbcConnection DbConnection = new OdbcConnection("ConnectionString"))
{
  DbConnection.Open();
  using (OdbcCommand DbCommand = DbConnection.CreateCommand())
  {
    DbCommand.CommandText = "INSERT...";
    DbCommand.Parameters.Add("@Name", OdbcType.Text, 20).Value = "name";
    DbCommand.ExecuteNonQuery();

    DbCommand.Parameters.Clear();
    DbCommand.Parameters.Add("@Name", OdbcType.Text, 20).Value = "name2";
    DbCommand.ExecuteNonQuery();
  }
}