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CREATE TABLE `user` (
`id` int(5) unsigned NOT NULL AUTO_INCREMENT,
`name` varchar(10) DEFAULT NULL,
`password` varchar(10) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=4 DEFAULT CHARSET=latin1
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1 name1 123456
2 name2 123456
3 name3 123456
4 name4 NULL
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£¨1£©select count(*) from `user`
£¨2£©select count(name) from `user`
£¨3£©select count(password) from `user`
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create database sample;
create table 't_user' (
'id' int(11) not null auto_increment,
'name' varchar(100) not null default '',
primary key ('id')
) type=myisam;
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-> 'MySQL'
mysql> select CONCAT('My', NULL, 'QL');
-> NULL
mysql> select CONCAT(14.3);
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Query OK, 1 row affected (0.02 sec)
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mysql>use test;
Database changed
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myaql>create table user(SID VARCHAR(11), name VARCHAT(6) );
Query OK, 0 rows affected (0.08 sec)
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