BEGIN END

Syntax

NOT ATOMIC is required when used outside of a stored procedure. Inside stored procedures or within an anonymous block, BEGIN alone starts a new anonymous block.

Description

BEGIN ... END syntax is used for writing compound statements. 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 (i.e., ;) statement delimiter. statement_list is optional, which means that the empty compound statement (BEGIN END) is legal.

Note that END will perform a commit. If you are running in mode, every statement will be committed separately. If you are not running in autocommit mode, you must execute a or after END to get the database up to date.

Use of multiple statements requires that a client is able to send statement strings containing the statement delimiter. This is handled in the with the command. Changing the ; end-of-statement delimiter (for example, to//) allows ; to be used in a program body.

A compound statement within a can be . end_label cannot be given unless begin_label also is present. If both are present, they must be the same.

BEGIN ... END constructs can be nested. Each block can define its own variables, a CONDITION, a HANDLER and a , which don't exist in the outer blocks. The most local declarations override the outer objects which use the same name (see example below).

The declarations order is the following:

Note that DECLARE HANDLER contains another BEGIN ... END construct.

Here is an example of a very simple, anonymous block:

Below is an example of nested blocks in a stored procedure:

In this example, a variable, x is declared in the outter block. But in the inner block x is re-declared as a and an y variable is declared. The inner shows the "new" value of x, and the value of y. But when x is selected in the outer block, the "old" value is returned. The final doesn't try to read y, because it doesn't exist in that context.

See Also

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