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.
(in System.Data.dll)
Visual Basic (Declaration)
Public Overrides Function ExecuteScalar As Object
Dim instance As SqlCommand
Dim returnValue As Object
returnValue = instance.ExecuteScalar()
public override Object ExecuteScalar()
public:
virtual Object^ ExecuteScalar() override
public override function ExecuteScalar() : Object
Return Value
Type:
System..::.ObjectThe first column of the first row in the result set, or a null reference (Nothing in Visual Basic) if the result set is empty. Returns a maximum of 2033 characters.
Implements
IDbCommand..::.ExecuteScalar()()()
| Exception | Condition |
|---|
| SqlException | An exception occurred while executing the command against a locked row. This exception is not generated when you are using Microsoft .NET Framework version 1.0. |
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 that you need to generate the single value using the data returned by a SqlDataReader.
A typical ExecuteScalar query can be formatted as in the following C# example:
cmd.CommandText = "SELECT COUNT(*) FROM dbo.region";
Int32 count = (Int32) cmd.ExecuteScalar();
The following example creates a SqlCommand and then executes it using ExecuteScalar. The example is passed a string representing a new value to be inserted into a table, and a string to use to connect to the data source. The function returns the new Identity column value if a new row was inserted, 0 on failure.
Public Function AddProductCategory( _
ByVal newName As String, ByVal connString As String) As Integer
Dim newProdID As Int32 = 0
Dim sql As String = _
"INSERT INTO Production.ProductCategory (Name) VALUES (@Name); " _
& "SELECT CAST(scope_identity() AS int);"
Using conn As New SqlConnection(connString)
Dim cmd As New SqlCommand(sql, conn)
cmd.Parameters.Add("@Name", SqlDbType.VarChar)
cmd.Parameters("@Name").Value = newName
Try
conn.Open()
newProdID = Convert.ToInt32(cmd.ExecuteScalar())
Catch ex As Exception
Console.WriteLine(ex.Message)
End Try
End Using
Return newProdID
End Function
static public int AddProductCategory(string newName, string connString)
{
Int32 newProdID = 0;
string sql =
"INSERT INTO Production.ProductCategory (Name) VALUES (@Name); "
+ "SELECT CAST(scope_identity() AS int)";
using (SqlConnection conn = new SqlConnection(connString))
{
SqlCommand cmd = new SqlCommand(sql, conn);
cmd.Parameters.Add("@Name", SqlDbType.VarChar);
cmd.Parameters["@name"].Value = newName;
try
{
conn.Open();
newProdID = (Int32)cmd.ExecuteScalar();
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
}
return (int)newProdID;
}
Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
.NET Framework
Supported in: 3.5, 3.0, 2.0, 1.1, 1.0
.NET Compact Framework
Supported in: 3.5, 2.0, 1.0
Reference
Other Resources