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This chapter discusses stored programs and views, which are database objects defined in terms of SQL code that is stored on the server for later execution.
Stored programs include these objects:
Stored routines, that is, stored procedures and functions. A stored procedure is invoked using the
CALLstatement. A procedure does not have a return value but can modify its parameters for later inspection by the caller. It can also generate result sets to be returned to the client program. A stored function is used much like a built-in function. you invoke it in an expression and it returns a value during expression evaluation.
Triggers. A trigger is a named database object that is associated with a table and that is activated when a particular event occurs for the table, such as an insert or update.
Events. An event is a task that the server runs according to schedule.
Views are stored queries that when referenced produce a result set. A view acts as a virtual table.
This chapter describes how to use stored programs and views. The following sections provide additional information about SQL syntax for statements related to these objects:
For each object type, there are
DROPstatements that control which objects exist and how they are defined. See Section 13.1, “Data Definition Statements”.
Stored program definitions include a body that may use compound statements, loops, conditionals, and declared variables. See Section 13.6, “Compound-Statement Syntax”.
In MySQL, metadata changes to objects referred to by stored programs are detected and cause automatic reparsing of the affected statements when the program is next executed. For more information, see Section 8.10.4, “Caching of Prepared Statements and Stored Programs”.