[begin_label:] BEGIN [statement_list] END [end_label]
BEGIN ... END
syntax is used for writing compound statements, which can appear
within stored programs. A compound statement can contain multiple
statements, enclosed by the BEGIN and
END keywords.
statement_list represents a list of one
or more statements, each terminated by a semicolon
(;) statement delimiter.
statement_list is optional, which means
that the empty compound statement (BEGIN END)
is legal.
Use of multiple statements requires that a client is able to send
statement strings containing the ; statement
delimiter. This is handled in the mysql
command-line client with the delimiter command.
Changing the ; end-of-statement delimiter (for
example, to //) permit ; to
be used in a program body. For an example, see
Section 19.1, “Defining Stored Programs”.
A BEGIN ...
END block can be labeled. Labels follow these rules:
end_labelcannot be given unlessbegin_labelis also present.If both
begin_labelandend_labelare present, they must be the same.Labels can be up to 16 characters long.
Labels are also permitted for the
LOOP,
REPEAT,
and
WHILE
statements.
The optional [NOT] ATOMIC clause is not
supported. This means that no transactional savepoint is set at
the start of the instruction block and the
BEGIN clause used in this context has no effect
on the current transaction.
Within all stored programs (stored procedures and functions,
triggers, and events), the parser treats
BEGIN [WORK]
as the beginning of a
BEGIN ...
END block. Begin a transaction in this context with
START
TRANSACTION instead.