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How to: Execute a Stored Procedure that Returns a Single Value

To execute a stored procedure that returns a single value, you can run TableAdapter query that is configured to run a stored procedure (for example, CustomersTableAdapter.CustomerCount()).

If your application does not use TableAdapters, call the ExecuteScalar method on a command object, setting its CommandType property to StoredProcedure. ("Command object" refers to the specific command for the .NET Framework Data Provider your application is using. For example, if your application is using the .NET Framework Data Provider for SQL Server, the command object would be SqlCommand.)

The following examples show how to execute stored procedures that return single values from a database using either TableAdapters or command objects. For more information on querying with TableAdapters and commands, see Filling Datasets with Data.

NoteNote

Your computer might show different names or locations for some of the Visual Studio user interface elements in the following instructions. The Visual Studio edition that you have and the settings that you use determine these elements. For more information, see Customizing Development Settings.

This example shows how to create a TableAdapter query using the TableAdapter Query Configuration Wizard, and then it provides information on how to declare an instance of the TableAdapter and execute the query.

To execute a stored procedure that returns a single value using a TableAdapter

  1. Open a dataset in the Dataset Designer. For more information, see How to: Open a Dataset in the Dataset Designer.

  2. If you do not already have one, create a TableAdapter. For more information on creating TableAdapters, see How to: Create TableAdapters.

  3. If you already have a query on your TableAdapter that uses a stored procedure to return a single value, skip to the next procedure, "To declare an instance of the TableAdapter and execute the query." Otherwise, continue with step 4 to create a new query that returns a single value.

  4. Right-click the TableAdapter that you want, and use the shortcut menu to add a query.

    The TableAdapter Query Configuration Wizard opens.

  5. Select Use existing stored procedure, and then click Next.

  6. Select a stored procedure from the drop-down list, and then click Next.

  7. Select the option to return A single value, and then click Next.

  8. Provide a name for the query.

  9. Click Next or Finish to complete the wizard; the query is added to the TableAdapter.

  10. Build your project.

To declare an instance of the TableAdapter and execute the query

  1. Declare an instance of the TableAdapter that contains the query you want to execute.

    • To create an instance using design-time tools, drag the TableAdapter that you want from the Toolbox. (Components in your project now appear in the Toolbox under a heading that matches your project name.) If the TableAdapter does not appear in the Toolbox, then you may need to build your project.

      -or-

    • To create an instance in code, replace the following code with the names of your DataSet and TableAdapter.

      Dim tableAdapter As New DataSetTableAdapters.TableAdapter

      Note Note

      TableAdapters are not actually located inside their associated dataset classes. Each dataset has a corresponding collection of TableAdapters in its own namespace. For example, if you have a dataset named SalesDataSet, there would be a SalesDataSetTableAdapters namespace that contains its TableAdapters.

  2. Call your query as you would call any other method in code. Your query is a method on the TableAdapter. Replace the following code with the names of your TableAdapter and query. You will also need to pass in any parameters required by your query. If you are not sure if your query requires parameters, or what parameters it requires, then check IntelliSense for the required signature of the query. Depending on whether your query takes parameters or not, the code would look similar to one of the following examples:

    TableAdapter.Query()

    TableAdapter.Query(Parameters)

    The complete code to declare an instance of the TableAdapter and execute the query should look similar to the following:

    Dim tableAdapter As New NorthwindDataSetTableAdapters.CustomersTableAdapter()
    
    Dim returnValue As Integer
    returnValue = CType(tableAdapter.GetCustomerCount(), Integer)
    

The following example shows how to create a command and execute a stored procedure that returns a single value. For information on setting and getting parameter values for a command, see How to: Set and Get Parameters for Command Objects.

This example uses the SqlCommand object and requires:

  • References to the System, System.Data, and System.Xml namespaces.

  • A data connection named SqlConnection1.

  • A table named Customers in the data source that SqlConnection1 connects to. (Otherwise, you need a valid SQL statement for your data source).

To execute a stored procedure that returns a single value using a DataCommand

  • Add the following code to a method that you want to execute the code from. You return single values by calling the ExecuteScalar method of a command (for example, ExecuteScalar). The data is returned in an object.

    Dim sqlConnection1 As New SqlConnection("Your Connection String")
    Dim cmd As New SqlCommand
    Dim returnValue As Object
    
    cmd.CommandText = "StoredProcedureName"
    cmd.CommandType = CommandType.StoredProcedure
    cmd.Connection = sqlConnection1
    
    sqlConnection1.Open()
    
    returnValue = cmd.ExecuteScalar()
    
    sqlConnection1.Close()
    
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