MySQL stored procedure and function differences introduced

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A stored procedure is a collection of user-defined sets of SQL statements that involve a task for a particular table or other object, a user can call a stored procedure, and a function is usually a method defined by a database that takes parameters and returns a value of some type and does not involve a particular user table.

There are several differences between stored procedures and functions:

1) In general, the function of the stored procedure implementation is a little more complicated, and the function's realization function is relatively strong. Stored procedures, powerful, can perform a series of database operations, including modifying tables; user-defined functions cannot be used to perform a set of actions that modify the state of a global database.

2) for stored procedures, parameters, such as recordsets, can be returned, and functions can only return values or table objects. A function can only return one variable, and a stored procedure may return multiple. Stored procedure parameters can have in,out,inout three types, and functions can only have in class ~ ~ ~ The stored procedure declaration does not require a return type, and the function declaration needs to describe the return type, and the function body must contain a valid return statement.

3) Stored procedures, you can use the non-deterministic function, not allowed in the user-defined function body of the built-in non-deterministic function.

4) The stored procedure is typically executed as a separate part (EXECUTE statement execution), and the function can be invoked as part of a query statement (select Call), since the function can return a Table object, so it can be located in the query statement after the FROM keyword. Stored procedures are not available in SQL statements, and functions can be used.

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MySQL stored procedure and function differences introduced