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OleDbCommand.ExecuteScalar Method

Executes the query, and returns the first column of the first row in the result set returned by the query. Additional columns or rows are ignored.

Namespace: System.Data.OleDb
Assembly: System.Data (in system.data.dll)

public override Object ExecuteScalar ()
public Object ExecuteScalar ()
public override function ExecuteScalar () : Object
Not applicable.

Return Value

The first column of the first row in the result set, or a null reference if the result set is empty.

Exception typeCondition

InvalidOperationException

Cannot execute a command within a transaction context that differs from the context in which the connection was originally enlisted.

Use the ExecuteScalar method to retrieve a single value, for example, an aggregate value, from a data source. This requires less code than using the ExecuteReader method, and then performing the operations that are required to generate the single value using the data returned by an OleDbDataReader.

A typical ExecuteScalar query can be formatted as in the following C# example:

CommandText = "SELECT COUNT(*) FROM region";
Int32 count = (int32) ExecuteScalar();

The following example creates an OleDbCommand and then executes it using ExecuteScalar. The example is passed a string that is an SQL statement that returns an aggregate result, and a string to use to connect to the data source.

public void CreateMyOleDbCommand(string queryString, 
    OleDbConnection connection) 
{
    OleDbCommand command = new OleDbCommand(queryString, connection);
    command.Connection.Open();
    command.ExecuteScalar();
    connection.Close();
}

Windows 98, Windows Server 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

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