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Specifies a compound statement.
[ statement-label : ] BEGIN [ [ NOT ] ATOMIC ] [ local-declaration; ... ] statement-list [ EXCEPTION [ exception-case ... ] ] END [ statement-label ]
local-declaration : variable-declaration | cursor-declaration | exception-declaration | temporary-table-declaration
exception-case : WHEN exception-name [, ... ] THEN statement-list | WHEN OTHERS THEN statement-list
variable-declaration and exception-declaration : see the DECLARE statement
cursor-declaration : see the DECLARE CURSOR statement
temporary-table-declaration : see the DECLARE LOCAL TEMPORARY TABLE statement
If the ending statement-label is specified, it must match the beginning statement-label. The LEAVE statement can be used to resume execution at the first statement after the compound statement. The compound statement that is the body of a procedure or trigger has an implicit label that is the same as the name of the procedure or trigger.
An atomic statement is a statement that is executed completely or not at all. For example, an UPDATE statement that updates thousands of rows might encounter an error after updating many rows. If the statement does not complete, all changes revert back to their original state. Similarly, if you specify that the BEGIN statement is atomic, the statement is executed either in its entirety or not at all.
Immediately following the BEGIN, a compound statement can have local declarations for objects that only exist within the compound statement. A compound statement can have a local declaration for a variable, a cursor, a temporary table, or an exception. Local declarations can be referenced by any statement in that compound statement, or in any compound statement nested within it. Local declarations of the compound statement are visible to the exception handlers for the statement. Local declarations are not visible to other procedures that are called from within a compound statement.
The body of a procedure or trigger is a compound statement. Compound statements can also be used in control statements within a procedure or trigger.
A compound statement allows one or more SQL statements to be grouped together and treated as a unit. A compound statement starts with the keyword BEGIN and ends with the keyword END.
BEGIN, which identifies a compound statement, comprises part of optional ANSI/ISO SQL Language Feature P002.
The body of a procedure or trigger is a compound statement.
CREATE PROCEDURE TopCustomer (OUT TopCompany CHAR(35), OUT TopValue INT) BEGIN DECLARE err_notfound EXCEPTION FOR SQLSTATE '02000'; DECLARE curThisCust CURSOR FOR SELECT CompanyName, CAST( sum( SalesOrderItems.Quantity * Products.UnitPrice ) AS INTEGER) VALUE FROM GROUPO.Customers LEFT OUTER JOIN SalesOrders LEFT OUTER JOIN SalesOrderItems LEFT OUTER JOIN Products GROUP BY CompanyName; DECLARE ThisValue INT; DECLARE ThisCompany CHAR( 35 ); SET TopValue = 0; OPEN curThisCust; CustomerLoop: LOOP FETCH NEXT curThisCust INTO ThisCompany, ThisValue; IF SQLSTATE = err_notfound THEN LEAVE CustomerLoop; END IF; IF ThisValue > TopValue THEN SET TopValue = ThisValue; SET TopCompany = ThisCompany; END IF; END LOOP CustomerLoop; CLOSE curThisCust; END;
The example below declares the following variables:
BEGIN DECLARE v1 INT = 5 DECLARE v2, v3 CHAR(10) = 'abc' // ... END