sqlÖÐallʲôÒâ˼
sql ÖÐµÄ all Åú×¢ÅÌÎʽ«·µ»ØËùÓÐÆ¥ÅäÐУ¬°üÀ¨Öظ´ÐС£Ê¹Óà all ¿É½ûÓÃÈ¥ÖØ£¬ÔÊÐí¶àÐоßÓÐÏàֵͬ£ºÌí¼Ó all ÖÁ select Óï¾äÖУºselect all column_name(s) from table_name where condition¡£µ±ÐèÒª°üÀ¨Öظ´Öµ¡¢ÅÌËãÐÐÊý»ò¾ÛºÏÖµ¡¢ÔÚ×ÓÅÌÎÊÖнûÓÃÈ¥ÖØʱʹÓà all¡£
SQL ÖÐµÄ ALL
ʲôÊÇ ALL£¿
ALL ÊÇ SQL ÖеÄÒ»¸öÒªº¦×Ö£¬ÓÃÓÚָʾÅÌÎÊÓ¦·µ»Ø±íÖÐËùÓÐÆ¥ÅäµÄÐУ¬¶ø²»¹ÜÊÇ·ñÖظ´¡£»»¾ä»°Ëµ£¬ALL ½ûÓÃÈ¥ÖØ£¬ÔÊÐíÅÌÎÊ·µ»Ø¾ßÓÐÏàֵͬµÄ¶àÐС£
ÔõÑùʹÓà ALL£¿
ҪʹÓà ALL£¬½«ÆäÌí¼Óµ½ SELECT Óï¾äÖУ¬ÈçÏÂËùʾ£º
SELECT ALL column_name(s) FROM table_name WHERE condition;
µÇ¼ºó¸´ÖÆ
Àý 1
¼ÙÉèÓÐÒ»¸öÃûΪ “customers” µÄ±í£¬ÆäÖаüÀ¨¿Í»§Êý¾Ý£º
| customer_id | customer_name | |-------------|---------------| | 1 | John Doe | | 2 | Jane Doe | | 3 | John Doe |
µÇ¼ºó¸´ÖÆ
ÈôÊDz»Ê¹Óà ALL£¬SELECT Óï¾ä½«Ö»·µ»ØΨһЧ¹û£º
SELECT customer_name FROM customers WHERE customer_id = 1;
µÇ¼ºó¸´ÖÆ
Êä³ö£º
John Doe
µÇ¼ºó¸´ÖÆ
¿ÉÊÇ£¬ÈôÊÇʹÓà ALL£¬ÅÌÎʽ«·µ»ØËùÓÐÆ¥ÅäµÄÐУ¬°üÀ¨Öظ´Öµ£º
SELECT ALL customer_name FROM customers WHERE customer_id = 1;
µÇ¼ºó¸´ÖÆ
Êä³ö£º
John Doe John Doe
µÇ¼ºó¸´ÖÆ
ºÎʱʹÓà ALL£¿
ALL ͨ³£ÓÃÓÚÒÔÏÂÇéÐΣº
ÐèÒª·µ»ØËùÓÐÆ¥ÅäµÄÐУ¬°üÀ¨Öظ´Öµ¡£
ÐèÒªÅÌËãÐÐÊý»ò¾ÛºÏÖµ£¨Èç SUM ºÍ COUNT£©£¬ÆäÖÐÖظ´ÖµºÜÖ÷Òª¡£
ÔÚ×ÓÅÌÎÊÖУ¬ÐèÒª½ûÓÃÈ¥ÖØÒÔ»ñµÃ׼ȷµÄЧ¹û¡£
×¢ÖØ£º
ʹÓà ALL ʱÐèҪעÖØÒÔϼ¸µã£º
ALL »áÔöÌíÅÌÎʵÄÖ´ÐÐʱ¼äºÍ×ÊÔ´ÏûºÄ¡£
ALL »áµ¼ÖÂЧ¹û¼¯ÖаüÀ¨´ó×ÚÖظ´Êý¾Ý£¬´Ó¶øÓ°ÏìºóÐø´¦ÀíµÄЧÂÊ¡£
ÔÚ´ó´ó¶¼ÇéÐÎÏ£¬³ý·ÇÃ÷È·ÐèÒªÖظ´µÄÖµ£¬²»È»²»½¨ÒéʹÓà ALL¡£
ÒÔÉϾÍÊÇsqlÖÐallʲôÒâ˼µÄÏêϸÄÚÈÝ£¬¸ü¶àÇë¹Ø×¢±¾ÍøÄÚÆäËüÏà¹ØÎÄÕ£¡