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IDbCommand.ExecuteScalar Method

Executes the query, and returns the first column of the first row in the resultset returned by the query. Extra columns or rows are ignored.

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

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

Return Value

The first column of the first row in the resultset.

Use the ExecuteScalar method to retrieve a single value (for example, an aggregate value) from a database. This requires less code than using the ExecuteReader method, and then performing the operations necessary to generate the single value using the data returned by an IDataReader.

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

 CommandText = "select count(*) as NumberOfRegions from region";
 Int32 count = (int) ExecuteScalar();

If the first column of the first row in the resultset is not found, a null reference is returned. If the value in the database is a null reference (Nothing in Visual Basic), the query returns DBNull.Value.

The following example creates an instance of the derived class, SqlCommand, and then executes it using ExecuteScalar. The example is passed a string that is a Transact-SQL statement that returns an aggregate result, and a string to use to connect to the data source.

public void CreateSqlCommand(
    string queryString, SqlConnection connection) 
{
    SqlCommand command = new 
        SqlCommand(queryString, connection);
    command.Connection.Open();
    command.ExecuteScalar();
    connection.Close();
}

Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, 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

.NET Compact Framework

Supported in: 2.0, 1.0

XNA Framework

Supported in: 1.0

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