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MariaDB [test]> select * from linux; /检索所有列+-------+--------+------+ | user | passwd | sex |+-------+--------+------+| user1 | 111 | boy || user2 | 222 | girl |+-------+--------+------+2 rows in set (0.00 sec)MariaDB [test]> select sex from linux; 利用SELECT语句从linux表中检索一个名为sex的列+------+| sex |+------+| boy || girl |+------+2 rows in set (0.00 sec)MariaDB [test]> select user,passwd from linux; /检索多个列+-------+--------+| user | passwd |+-------+--------+| user1 | 111 || user2 | 222 |+-------+--------+2 rows in set (0.00 sec)MariaDB [test]> select sex from linux where user='user1'; /配合where进行条件查找+-----+| sex |+-----+| boy |+-----+1 row in set (0.00 sec)
DISTINCT
MariaDB [test]> select * from linux;+-------+--------+------+| user | passwd | sex |+-------+--------+------+| user1 | 111 | boy || user2 | 222 | girl || user3 | 333 | boy || user4 | 444 | boy || user5 | 555 | boy |+-------+--------+------+5 rows in set (0.01 sec)MariaDB [test]> select distinct sex from linux;+------+| sex |+------+| boy || girl |+------+2 rows in set (0.00 sec)MariaDB [test]> select distinct user,sex from linux;+-------+------+| user | sex |+-------+------+| user1 | boy || user2 | girl || user3 | boy | /在指定多行的时候会这样显示，因为把每行看做一个单位的话，他们都不一样| user4 | boy || user5 | boy |+-------+------+5 rows in set (0.00 sec)
限制结果 LIMIT
MariaDB [test]> select distinct user,sex from linux;+-------+------+| user | sex |+-------+------+| user1 | boy || user2 | girl || user3 | boy || user4 | boy || user5 | boy |+-------+------+5 rows in set (0.00 sec)MariaDB [test]> select distinct user,sex from linux limit 3; /限制只显示前3行+-------+------+| user | sex |+-------+------+| user1 | boy || user2 | girl || user3 | boy |+-------+------+3 rows in set (0.00 sec)MariaDB [test]> select distinct user,sex from linux limit 2; /限制只显示前两行+-------+------+| user | sex |+-------+------+| user1 | boy || user2 | girl |+-------+------+2 rows in set (0.00 sec)MariaDB [test]> select distinct user,sex from linux limit 2,1; 从第2行开始，往后检索一行+-------+-----+| user | sex |+-------+-----+| user3 | boy |+-------+-----+1 row in set (0.00 sec)MariaDB [test]> select distinct user,sex from linux limit 2,3; 往后检索3行+-------+-----+| user | sex |+-------+-----+| user3 | boy || user4 | boy || user5 | boy |+-------+-----+3 rows in set (0.01 sec)在行数不够的情况下只会显示能显示的
使用完全限定的表名
MariaDB [test]> select linux.user from test.linux;+-------+ linux 表的 user列| user | 来自 test 数据库的 linux 表+-------+| user1 || user2 || user3 || user4 || user5 |+-------+5 rows in set (0.00 sec)MariaDB [test]> select user.user from mysql.user;+------+| user |+------+| root || root || || aom || root || || root |+------+7 rows in set (0.00 sec)
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