MySQL 8.3 Release Notes
The DECLARE statement is used to
define various items local to a program:
Local variables. See Section 15.6.4, “Variables in Stored Programs”.
Conditions and handlers. See Section 15.6.7, “Condition Handling”.
Cursors. See Section 15.6.6, “Cursors”.
DECLARE is permitted only inside a
BEGIN ... END
compound statement and must be at its start, before any other
statements.
Declarations must follow a certain order. Cursor declarations must appear before handler declarations. Variable and condition declarations must appear before cursor or handler declarations.