select count(1) from table1 这句话count里有个1是什么意思？

[musicsoul]

select count(1) from table1 这句话count里有个1是什么意思？

谢谢！！！

[shuixin13]

表的第一列..

就好像

SELECT ... FORM ... ORDER BY 1 DESC;

[lehool]

CREATE TABLE `table1` (
`a` mediumint(4) NOT NULL auto_increment,
`b` varchar(20) NOT NULL default '',
`c` varchar(20) NOT NULL default '',
`d` tinyint(2) NOT NULL default '1',
`e` varchar(50) default NULL,
PRIMARY KEY (`a`),
UNIQUE KEY `a` (`a`)
) TYPE=MyISAM

select count(1) from table1 == select count(a) from table1 !!

[fish21cn]

哦。又学到了。

[lxf_1976]

*^_^*

一直都不知道！

学习！！！！

[loveflea]

倏然我知道是表的第一列..但感觉用什么数字效果都是一样的！嗬嗬！

mysql> desc logoff;
+------------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+------------+-------------+------+-----+---------+-------+
| usernumber | varchar(15) | YES | MUL | NULL | |
+------------+-------------+------+-----+---------+-------+
1 row in set (0.41 sec)

mysql> select count(1) from logoff;
+----------+
| count(1) |
+----------+
| 1461742 |
+----------+
1 row in set (0.03 sec)

mysql> select count(1000) from logoff;
+-------------+
| count(1000) |
+-------------+
| 1461742 |
+-------------+
1 row in set (0.00 sec)

mysql> select count(0) from logoff;
+----------+
| count(0) |
+----------+
| 1461742 |
+----------+
1 row in set (0.00 sec)

mysql> select count(-1) from logoff;
+-----------+
| count(-1) |
+-----------+
| 1461742 |
+-----------+
1 row in set (0.00 sec)

[shuixin13]

呵呵,
是的.

就好像分组后 COUNT(*) = COUNT(Col1) 一样.
参数已没有什么实际意义了.

[htdqy]

牛人真多啊～

[cantops]

学到了。 开心中