Syntax:
[begin_label:] REPEAT
    statement_list
UNTIL search_condition
END REPEAT [end_label]

The statement list within a REPEAT statement is repeated until the
search_condition expression is true. Thus, a REPEAT always enters the
loop at least once. statement_list consists of one or more statements,
each terminated by a semicolon (;) statement delimiter.

A REPEAT statement can be labeled. For the rules regarding label use,
see [HELP labels].

URL: https://dev.mysql.com/doc/refman/5.7/en/repeat.html

