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declare @i int
set @i=1
while @i<30
begin
insert into test (userid) values(@i)
set @i=@i+1
end
---------------
while Ìõ¼þ
begin
Ö´ÐвÙ×÷
set @i=@i+1
end
WHILE
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WHILE Boolean_expression
     { sql_statement | statement_block }
     [ BREAK ]
     { sql_statement | statement_block }
     [ CONTINUE ]
²ÎÊý
Boolean_expression
·µ»Ø TRUE »ò FALSE µÄ±í´ïʽ¡£Èç¹û²¼¶û±í´ïʽÖк¬ÓÐ SELECT Óï¾ä£¬±ØÐëÓÃÔ²À¨ºÅ½« SELECT Óï¾äÀ¨ÆðÀ´¡£
{sql_statement | statement_block}
Transact-SQL Óï¾ä»òÓÃÓï¾ä¿é¶¨ÒåµÄÓï¾ä·Ö×é¡£ÈôÒª¶¨ÒåÓï¾ä¿é£¬ÇëʹÓÿØÖÆÁ÷¹Ø¼ü×Ö BEGIN ºÍ END¡£
BREAK
µ¼Ö´Ó×îÄÚ²ãµÄ WHILE Ñ­»·ÖÐÍ˳ö¡£½«Ö´ÐгöÏÖÔÚ END ¹Ø¼ü×ÖºóÃæµÄÈκÎÓï¾ä£¬END ¹Ø¼ü×ÖΪѭ»·½áÊø±ê¼Ç¡£
CONTINUE
ʹ WHILE Ñ­»·ÖØÐ¿ªÊ¼Ö´ÐУ¬ºöÂÔ CONTINUE ¹Ø¼ü×ÖºóµÄÈκÎÓï¾ä¡£
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ʾÀý
A. ÔÚǶÌ×µÄ IF...ELSE ºÍ WHILE ÖÐʹÓà BREAK ºÍ CONTINUE
ÔÚÏÂÀýÖУ¬Èç¹ûƽ¾ù¼Û¸ñÉÙÓÚ $30£¬WHILE Ñ­»·¾Í½«¼Û¸ñ¼Ó±¶£¬È»ºóÑ¡Ôñ×î¸ß¼Û¡£Èç¹û×î¸ß¼ÛÉÙÓÚ»òµÈÓÚ $50£¬WHILE Ñ­»·ÖØÐÂÆô¶¯²¢Ôٴν«¼Û¸ñ¼Ó±¶¡£¸ÃÑ­»·²»¶ÏµØ½«¼Û¸ñ¼Ó±¶Ö±µ½×î¸ß¼Û¸ñ³¬¹ý $50£¬È»ºóÍ˳ö WHILE Ñ­»·²¢´òÓ¡Ò»ÌõÏûÏ¢¡£
USE pubs
GO
WHILE (SELECT AVG(price) from titles) < $30
BEGIN
    UPDATE titles
       SET price = price * 2
    SELECT MAX(price) from titles
    IF (SELECT MAX(price) from titles) > $50
       BREAK
    ELSE
       CONTINUE
END
PRINT 'Too much for the market to bear'
B. ÔÚ´øÓÐÓαêµÄ¹ý³ÌÖÐʹÓà WHILE
ÒÔÏ嵀 WHILE ½á¹¹ÊÇÃûΪ count_all_rows ¹ý³ÌÖеÄÒ»²¿·Ö¡£ÏÂÀýÖУ¬¸Ã WHILE ½á¹¹²âÊÔÓÃÓÚÓαêµÄº¯Êý @@FETCH_STATU


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(
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[×Ö¶Î1] nVarChar(50) default 'ĬÈÏÖµ' null ,
[×Ö¶Î2] ntext null ,
[×Ö¶Î3] datetime,
[×Ö¶Î4] money null ,
[×Ö¶Î5] int default 0,
[×Ö¶Î6] Decimal (12,4) default 0,
[×Ö¶Î7] image null ,
)
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