Stored routines are one of the newer additions to MySQL and, as such, are significantly less optimized than other components of the server. As a result, it’s generally not advisable for your application to rely entirely on stored routines, as doing so will likely degrade performance significantly. That said, stored routines do have a role […]
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Under MySQL’s current implementation, a stored function can only return a single value. However, there is a not-so-pretty workaround: create a temporary table within the function body to store the values returned, and then access this table outside the function. Here’s an example: mysql> DELIMITER // mysql> CREATE FUNCTION get_airport_names(min_terminals INT) -> RETURNS INT -> BEGIN -> DECLARE count INT DEFAULT 0; -> CREATE TEMPORARY TABLE -> IF NOT EXISTS -> get_airport_names_out (value VARCHAR(255)); -> DELETE FROM get_airport_names_out; -> INSERT INTO get_airport_names_out (value) -> SELECT AirportName FROM airport -> WHERE NumTerminals >= min_terminals; […]
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As your SQL business logic becomes more complex, you might find yourself repeatedly writing blocks of SQL statements to perform the same database operation at the application level—for example, inserting a set of linked records or performing calculations on a particular result set. In these situations, it usually makes sense to turn this block of […]
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