SqlConnection Class

In This Topic

Represents an open connection to SQL Server.

Syntax

Visual Basic
C#

'Declaration
 
Public Class SqlConnection 
   Inherits Devart.Common.DbConnectionBase
   Implements System.ComponentModel.IComponent, System.Data.IDbConnection, System.ICloneable, System.IDisposable

public class SqlConnection : Devart.Common.DbConnectionBase, System.ComponentModel.IComponent, System.Data.IDbConnection, System.ICloneable, System.IDisposable

Remarks

A SqlConnection object represents a unique connection to SQL Server. Use it in conjunction with SqlCommand, SqlDataReader, SqlDataAdapter or other components for convenient interoperation with SQL Server.

When you create an instance of SqlConnection, all properties are set to their initial values. For a list of these values, see ConnectionString.

If the SqlConnection goes out of scope, it is not closed. Therefore, you must explicitly close the connection by calling Close.

Note that SqlConnection instance is not guaranteed to be thread safe. You should avoid using the same SqlConnection in several threads at the same time. It is recommended to open a new connection per thread and to close it when the work is done. Actually, connections will not be created/disposed every time with the Pooling=true; connection string option - connections will be stored at connection pool. This boosts performance greatly.

A single SqlConnection can be used by many SqlCommand objects on the assumption that all operations will be done consecutively. In other words, you can not execute a SQL statement while an asynchronous operation is in progress.

This class supports cross-form data binding with the InterForm Technology.

Example

The following example creates a SqlCommand and a SqlConnection. The SqlConnection is opened and set as the Connection property. The example then calls ExecuteNonQuery method, and closes the connection. To accomplish this, the ExecuteNonQuery is passed a connection string and a query string that is SQL INSERT statement.

csharp

public void InsertRow(string myConnectionString)
{
  // If the connection string is empty, use default.
  if(myConnectionString == "")
  {
    myConnectionString = 
        "User Id=sa;Server=localhost;Initial Catalog=Test;";
  }
  SqlConnection myConn = new SqlConnection(myConnectionString);
  string myInsertQuery = "INSERT INTO DEPT VALUES (50,'Development','Philadelphia')";
  SqlCommand myCommand = new SqlCommand(myInsertQuery);
  myCommand.Connection = myConn;
  myConn.Open();
  try
  {
    myCommand.ExecuteNonQuery();
  }
  finally
  {
    myConn.Close();
  }
}

Visual Basic

Public Sub InsertRow(myConnectionString As String)
  ' If the connection string is empty, use default.
  If myConnectionString = "" Then
    myConnectionString = _
        "User Id=sa;Server=localhost;Initial Catalog=Test;"
  End If
  Dim myConn As New SqlConnection(myConnectionString)
  Dim myInsertQuery As String = "INSERT INTO DEPT VALUES (50,'Development','Philadelphia')"
  Dim myCommand As New SqlCommand(myInsertQuery)
  myCommand.Connection = myConn
  myConn.Open()
  Try
    myCommand.ExecuteNonQuery()
  Finally
    myConn.Close()
  End Try
End Sub

Inheritance Hierarchy

System.Object
   System.MarshalByRefObject
      System.ComponentModel.Component
         System.Data.Common.DbConnection
            Devart.Common.DbConnectionBase
               Devart.Data.SqlServer.SqlConnection

Reference

SqlConnection Members
Devart.Data.SqlServer Namespace
SqlDataAdapter Class
SqlCommand Class

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