How to: Add Global Queries to a Dataset
Global queries are SQL queries that return either a single (scalar) value or no value. Typically, global functions perform database operations such as inserts, updates, deletes, and the aggregating of information, such as returning a count of customers in a table or the total charges for all items in a particular order.
You add global queries by running the TableAdapter Query Configuration Wizard from within the Dataset Designer.
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To add a global query to a dataset
Open a dataset in the Dataset Designer. For more information, see How to: Open a Dataset in the Dataset Designer.
Drag a Query from the DataSet tab of the Toolbox onto an empty area of the Dataset Designer.
The TableAdapter Query Configuration Wizard opens.
Choose a connection for the query to use. You can either choose one from the list or create a new connection. If you create a new connection, you will have the option to save it to the application configuration file. For more information, see How to: Save and Edit Connection Strings.
Choose whether to use SQL statements or stored procedures.
Choose the stored procedure to use or, on the Choose a Query Type page of the wizard, choose the type of query you want and then click Next.
Provide a query that performs the desired task, for example, SELECT COUNT(*) AS CustomerCount FROM Customers.
Dragging a query directly onto the Dataset Designer creates a method that will only return a scalar (single) value. While the query or stored procedure you select may return more than a single value, the method created by the wizard will only return a single value. For example, the query might return the first column of the first row of the returned data.
Complete the wizard; the query is added to the Dataset Designer. For information on running the query, see How to: Execute TableAdapter Queries.