尊龙凯时人生就是博

sqlÖеÄÌõ¼þÅжÏÔõôд

sql ÖеÄÌõ¼þÅжϿÉÓÃÓÚ¹ýÂËÊý¾Ý£¬½ö·µ»ØÖª×ãÖ¸¶¨Ìõ¼þµÄÐС£where ×Ó¾äÓÃÓÚ¹ýÂËÐУ¬having ×Ó¾äÓÃÓÚ¹ýÂ˾ۺϺ¯ÊýÌìÉúµÄ×éЧ¹û¼¯ÖеÄÐС£Ìõ¼þÅжÏʹÓü´ÊÇ¡¢²»¼´ÊÇ¡¢´óÓÚ¡¢Ð¡ÓÚµÈÔËËã·ûÒÔ¼° and¡¢or¡¢not µÈÂß¼­ÔËËã·û¡£¿ÉÒÔǶÌ×Ìõ¼þÒÔ½¨Éè¸üÖØ´óµÄ¹ýÂËÌõ¼þ£¬Ç¶Ì×Ìõ¼þµÄÓÅÏȼ¶×ñÕÕÀ¨ºÅÄÚÌõ¼þ¡¢not ÔËËã·û¡¢and ÔËËã·û¡¢or ÔËËã·û¡£

SQL ÖеÄÌõ¼þÅжÏ

Ìõ¼þÅжÏÊÇ SQL ÅÌÎÊÖÐÓÃÓÚ¹ýÂËÊý¾Ý²¢½ö·µ»ØÖª×ãÌض¨Ìõ¼þµÄÐС£SQL ÖÐÓÐÁ½ÖÖÖ÷ÒªµÄÌõ¼þÅжϣº

WHERE ×Ӿ䣺ÓÃÓÚ¹ýÂËÐУ¬Ö»·µ»ØÖª×ãÖ¸¶¨Ìõ¼þµÄÐС£

HAVING ×Ӿ䣺ÓÃÓÚ¹ýÂËÓɾۺϺ¯Êý£¨Èç SUM¡¢COUNT »ò AVG£©ÌìÉúµÄ×éЧ¹û¼¯ÖеÄÐС£

WHERE ×Ó¾ä

WHERE ×Ó¾äλÓÚ SELECT Óï¾äµÄĩ⣬ÓÃÓÚÖ¸¶¨¹ýÂËÌõ¼þ¡£Ìõ¼þÓÉÒ»¸öÂß¼­±í´ïʽ×é³É£¬¸Ã±í´ïʽ¶ÔÐеÄÁÐÇóÖµ£¬²¢·µ»Ø TRUE »ò FALSE¡£

Óï·¨£º

SELECT column_name(s)
FROM table_name
WHERE condition;

µÇ¼ºó¸´ÖÆ

ʾÀý£º

SELECT *
FROM customers
WHERE age > 18;

µÇ¼ºó¸´ÖÆ

HAVING ×Ó¾ä

HAVING ×Ó¾äλÓÚ GROUP BY ×Ó¾äÖ®ºó£¬ÓÃÓÚ¹ýÂËÓɾۺϺ¯ÊýÌìÉúµÄ×éЧ¹û¼¯ÖеÄÐС£Ìõ¼þ¶Ô¾ÛºÏÖµÇóÖµ£¬²¢·µ»Ø TRUE »ò FALSE¡£

Óï·¨£º

SELECT column_name(s)
FROM table_name
GROUP BY group_column(s)
HAVING condition;

µÇ¼ºó¸´ÖÆ

ʾÀý£º

SELECT department_id, AVG(salary)
FROM employees
GROUP BY department_id
HAVING AVG(salary) > 50000;

µÇ¼ºó¸´ÖÆ

Ìõ¼þÔËËã·û

SQL ʹÓÃÒÔÏÂÔËËã·û¾ÙÐÐÌõ¼þÅжϣº

¼´ÊÇ£º =

²»¼´ÊÇ£º »ò !=

´óÓÚ£º >

СÓÚ£º

´óÓÚ»ò¼´ÊÇ£º >=

СÓÚ»ò¼´ÊÇ£º

LIKE£ºÓÃÓÚÆ¥Åäģʽ£¨ÀýÈ磬”LIKE ‘%john%'” Æ¥Åä°üÀ¨ “john” ×Ö·û´®µÄÐУ©

Âß¼­ÔËËã·û

SQL ʹÓÃÒÔÏÂÂß¼­ÔËËã·û×éºÏÌõ¼þ£º

AND£ºÂß¼­ÓëÔËËã·û£¬Ö»ÓÐÁ½¸öÌõ¼þ¶¼Îª TRUE ʱ²Å·µ»Ø TRUE¡£

OR£ºÂß¼­»òÔËËã·û£¬Ö»ÒªÓÐÒ»¸öÌõ¼þΪ TRUE ʱ¾Í·µ»Ø TRUE¡£

NOT£ºÂß¼­·ÇÔËËã·û£¬½«Ìõ¼þЧ¹ûÈ¡·´¡£

ǶÌ×Ìõ¼þ

¿ÉÒÔʹÓÃÀ¨ºÅǶÌ×Ìõ¼þÒÔ½¨Éè¸üÖØ´óµÄ¹ýÂËÌõ¼þ¡£Ç¶Ì×Ìõ¼þµÄÓÅÏȼ¶×ñÕÕÈçÏÂ˳Ðò£º

À¨ºÅÄÚµÄÌõ¼þ

NOT ÔËËã·û

AND ÔËËã·û

OR ÔËËã·û

ÒÔÉϾÍÊÇsqlÖеÄÌõ¼þÅжÏÔõôдµÄÏêϸÄÚÈÝ£¬¸ü¶àÇë¹Ø×¢±¾ÍøÄÚÆäËüÏà¹ØÎÄÕ£¡

ÃâÔð˵Ã÷£ºÒÔÉÏչʾÄÚÈÝȪԴÓÚÏàÖúýÌå¡¢ÆóÒµ»ú¹¹¡¢ÍøÓÑÌṩ»òÍøÂçÍøÂçÕûÀí£¬°æȨÕùÒéÓë±¾Õ¾Î޹أ¬ÎÄÕÂÉæ¼°¿´·¨Óë¿´·¨²»´ú±í尊龙凯时人生就是博ÂËÓÍ»úÍø¹Ù·½Ì¬¶È£¬Çë¶ÁÕß½ö×ö²Î¿¼¡£±¾ÎĽӴýתÔØ£¬×ªÔØÇë˵Ã÷À´ÓÉ¡£ÈôÄúÒÔΪ±¾ÎÄÇÖÕ¼ÁËÄúµÄ°æȨÐÅÏ¢£¬»òÄú·¢Ã÷¸ÃÄÚÈÝÓÐÈκÎÉæ¼°ÓÐÎ¥¹«µÂ¡¢Ã°·¸Ö´·¨µÈÎ¥·¨ÐÅÏ¢£¬ÇëÄúÁ¬Ã¦ÁªÏµ尊龙凯时人生就是博ʵʱÐÞÕý»òɾ³ý¡£

Ïà¹ØÐÂÎÅ

ÁªÏµ尊龙凯时人生就是博

18523999891

¿É΢ÐÅÔÚÏß×Éѯ

ÊÂÇéʱ¼ä£ºÖÜÒ»ÖÁÖÜÎ壬9:30-18:30£¬½ÚãåÈÕÐÝÏ¢

QR code
sitemap¡¢ÍøÕ¾µØͼ