WHILE condition LOOP statements; END LOOP;Code language: PostgreSQL SQL dialect and PL/pgSQL (pgsql) In this syntax, the condition is a boolean expression that evaluates to TRUE, FALSE or NULL. The WHILE loop statement continues to execute the statements between the LOOP and END LOOP as long...
Here’s the basic syntax of a while loop statement: [ <> ] while condition loop statements; end loop; In this syntax, PostgreSQL evaluates the condition before executing the statements. If the condition is true, it executes the statements. After each iteration, the while loop evaluates ...
Whereas the number of iterations through aWHILEloop is unknown until the loop completes, the number of iterations through aFORloop is known before the loop is entered. NumericFORloops iterate over a specified range of integers. The range is part of an iteration scheme, which is enclosed by th...
Introduction to PL/pgSQL Loop statement The loop defines an unconditional loop that executes a block of code repeatedly until terminated by an exit or return statement. The following illustrates the syntax of the loop statement: <> loop statements; end loop; Typically, you use an if statement ...
The statements are executed repeatedly as long as the specified condition is true. The execution of statements in the WHILE loop can be controlled from inside the loop with the BREAK and CONTINUE keywords.Transact-SQL syntax conventionsSyntaxSyntax for SQL Server, Azure SQL Database, Azure SQL ...
/*Set @min and @max beginning values for while loop and Begin while loop*/ DELIMITER $$ CREATE DEFINER=`root`@`localhost` PROCEDURE `repeat_loop_proc`() Begin set @Min := 1; select @max:= max(id) from Test_Tables; while (@min <= @max) ...
syntaxsql 複製 <join_hint> ::= { LOOP | HASH | MERGE | REMOTE } 引數{ LOOP |HASH |MERGE }指定查詢中的聯結應該使用迴圈、雜湊或合併。 使用 LOOP、 HASH或MERGE JOIN 會強制執行兩個數據表之間的特定聯結。 LOOP 不能與 RIGHT 或FULL 一起指定為聯結類型。 如需詳細資訊,請參閱聯結。
DECLARE done BOOLEAN; -- Initial value is NULL by default counter NUMBER := 0; BEGIN done := FALSE; -- Assign literal value WHILE done != TRUE -- Compare to literal value LOOP counter := counter + 1; done := (counter > 500); -- Assign value of BOOLEAN expression END LOOP; END...
变量常用在批处理或过程中,作为 WHILE、LOOP 或 IF...ELSE 块的计数器。 变量只能用在表达式中,不能代替对象名或关键字。 若要构造动态 SQL 语句,请使用 EXECUTE。 局部变量的作用域是其被声明时所在批处理。 表变量不一定是内存驻留。 在内存压力下,可以将属于表变量的页推送到tempdb。
SyntaxSQL Server、Azure SQL 資料庫 和 Azure SQL 受控執行個體 的語法。syntaxsql 複製 ALTER INDEX { index_name | ALL } ON { REBUILD { [ PARTITION = ALL [ WITH ( <rebuild_index_option> [ , ...n ] ) ] ] | [ PARTITION = partition_number [ WITH ( <single_partition_rebuild_index...