尊龙凯时人生就是搏

sqlÖв»¼´ÊÇij¸öÌõ¼þÔõôд³öÀ´

ÔÚ sql ÖУ¬”” ÔËËã·ûÓÃÓÚÌåÏÖ¡°²»¼´ÊÇ¡±Ä³¸öÌõ¼þ£¬Ó﷨Ϊ£ºselect from table_name where column_name value¡£ÀýÈ磺²éÕÒ name ²»¼´ÊÇ “john doe” µÄ¿Í»§£ºselect from customers where name ‘john doe’ £»²éÕÒ price ²»¼´ÊÇ 100 µÄ²úÆ·£ºselect * from products where price 100¡£

ÔõÑùʹÓà SQL ÌåÏÖ¡°²»¼´ÊÇ¡±Ä³¸öÌõ¼þ

ÔÚ SQL ÖУ¬Ê¹Óà “” ÔËËã·ûÌåÏÖ¡°²»¼´ÊÇ¡±¡£

Óï·¨£º

SELECT * FROM table_name WHERE column_name  value

µÇ¼ºó¸´ÖÆ

ÒÔÏÂʾÀýÑÝʾÔõÑùʹÓà “” ÔËËã·û£º

-- ²éÕÒËùÓÐÐÕÃû²»Îª "John Doe" µÄ¿Í»§
SELECT * FROM customers WHERE name  'John Doe';

-- ²éÕÒËùÓмÛÇ®²»Îª 100 µÄ²úÆ·
SELECT * FROM products WHERE price  100;

-- ²éÕÒËùÓж©µ¥ÈÕÆÚ²»Îª "2023-03-08" µÄ¶©µ¥
SELECT * FROM orders WHERE order_date  '2023-03-08';

µÇ¼ºó¸´ÖÆ

ÆäËû×¢ÖØÊÂÏ

“” ÔËËã·û»¹¿ÉÓÃÓÚ½ÏÁ¿ NULL Öµ¡£ÀýÈ磬ÒÔÏÂÅÌÎÊ·µ»ØËùÓоßÓÐ·Ç NULL Ãû³ÆµÄ¿Í»§£º

SELECT * FROM customers WHERE name  NULL;

µÇ¼ºó¸´ÖÆ

ʹÓà “” ÔËËã·ûʱ£¬ÇëÈ·±£Êý¾ÝÀàÐÍÆ¥Åä¡£ÀýÈ磬ÈôÊÇ “column_name” ÊÇÒ»¸ö×Ö·û´®£¬Ôò “value” Ò²±ØÐèÊÇÒ»¸ö×Ö·û´®¡£

ÒÔÉϾÍÊÇsqlÖв»¼´ÊÇij¸öÌõ¼þÔõôд³öÀ´µÄÏêϸÄÚÈÝ£¬¸ü¶àÇë¹Ø×¢±¾ÍøÄÚÆäËüÏà¹ØÎÄÕ£¡

ÃâÔð˵Ã÷£ºÒÔÉÏչʾÄÚÈÝȪԴÓÚÏàÖúýÌå¡¢ÆóÒµ»ú¹¹¡¢ÍøÓÑÌṩ»òÍøÂçÍøÂçÕûÀí£¬°æȨÕùÒéÓë±¾Õ¾Î޹أ¬ÎÄÕÂÉæ¼°¿´·¨Óë¿´·¨²»´ú±í尊龙凯时人生就是搏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尊龙凯时人生就是搏ʵʱÐÞÕý»òɾ³ý¡£

Ïà¹ØÐÂÎÅ

ÁªÏµ尊龙凯时人生就是搏

18523999891

¿É΢ÐÅÔÚÏß×Éѯ

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

QR code
sitemap¡¢ÍøÕ¾µØͼ