ExecuteScalar Method

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()

Return Value

Type: System.Object

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

Exception Condition
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();
}

.NET Framework
Available since 1.1
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