MySQL 8.0 Release Notes
MySQL 8.0 Source Code Documentation
System variables and user-defined variables can be used in stored
programs, just as they can be used outside stored-program context.
In addition, stored programs can use DECLARE to
define local variables, and stored routines (procedures and
functions) can be declared to take parameters that communicate
values between the routine and its caller.
To declare local variables, use the
DECLAREstatement, as described in Section 15.6.4.1, “Local Variable DECLARE Statement”.Variables can be set directly with the
SETstatement. See Section 15.7.6.1, “SET Syntax for Variable Assignment”.Results from queries can be retrieved into local variables using
SELECT ... INTOor by opening a cursor and usingvar_listFETCH ... INTO. See Section 15.2.13.1, “SELECT ... INTO Statement”, and Section 15.6.6, “Cursors”.var_list
For information about the scope of local variables and how MySQL resolves ambiguous names, see Section 15.6.4.2, “Local Variable Scope and Resolution”.
It is not permitted to assign the value DEFAULT
to stored procedure or function parameters or stored program local
variables (for example with a SET
statement). In MySQL 8.0, this results in a syntax
error.
var_name = DEFAULT