8.4. Invoking User-Defined Functions in SQL Statements


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8.4. Invoking User-Defined Functions in SQL Statements

Once the class is loaded and the function declared, you can include the user-defined function in SQL queries and data manipulation (DML) statements just as you normally use built-in functions in SQL. For example, if a stored procedure needs to convert an entry in miles to the equivalent measurement in kilometers, the stored procedure definition might look like the following:

CREATE PROCEDURE Expense_in_miles AS
    INSERT INTO Expense_item (item_name, distance, destination)
    VALUES (?, US2METRIC(?,'MILES'), ?);

Note that user-defined functions can be used in queries and DML but cannot be used in data definition statements, such as CREATE statements that define indexes, tables, or views.