使用子字符串条件连接表 [英] Joining Table with substring condition

问题描述

我有两张桌子:

create table t1(
id int unsigned not null auto_increment,
group varchar(3) not null,
number int unsigned zerofill,
used enum('YES','NO') default );

id   group   number  used
1    '110'   00001   'YES'
2    '110'   00002   'YES'
3    '110'   00003   'YES'
4    '210'   00001   'YES'
5    '210'   00002   'YES'
6    '210'   00003   'YES'
7    '310'   00001   'YES'

create table t2(
id int unsigned not null auto_increment,
number varchar(13) default null);

id   number  
1    '110-00001'
2    '110-00002'
3    '210-00002'
4    '310-00001'

我的第一个目标是找到 t1 中未在 t2 中使用的所有记录:

My First Goal is to find every record from t1 that not used in t2:

查询结果:

id   group   number  used
3    '110'   00003   'YES'
4    '210'   00001   'YES'
6    '210'   00003   'YES'

我的第二个目标是将列设置为否":

And my 2nd Goal is to Set the column used to be 'NO':

id   group   number  used
3    '110'   00003   'NO'
4    '210'   00001   'NO'
6    '210'   00003   'NO'

我尝试使用这样的查询:

I have tried to use the query like this :

  select * from t1 
left outer join t2 
             on t1.number = cast(substring(t2.number,8,5) as int) 
          where t2.id is null;

但 mySQL 说:

您的 SQL 语法有错误；检查手册对应于您的 MySQL 服务器版本以使用正确的语法'int) 附近，其中 tblpeserta.id 为空

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'int) where tblpeserta.id is null

对我的问题有更好的查询吗?！

is there a better query for my problem?!

推荐答案

尝试

UPDATE t1 LEFT JOIN t2
    ON t1.`group` = LEFT(t2.number, 3)
   AND t1.number = 0 + RIGHT(t2.number, 5)
   SET t1.used = 'NO'
 WHERE t2.id IS NULL

和选择

SELECT *
  FROM t1 LEFT JOIN t2
    ON t1.`group` = LEFT(t2.number, 3)
   AND t1.number = 0 + RIGHT(t2.number, 5)
 WHERE t2.id IS NULL

输出:

| ID | GROUP | NUMBER | USED |
------------------------------
|  3 |   110 |      3 |   NO |
|  4 |   210 |      1 |   NO |
|  6 |   210 |      3 |   NO |

SQLFiddle

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