[英]SQL query to search for string in a table?
嗨,我想在存储在mysql数据库中的表中搜索特定的字符串。 表格结构如下: -
+--------------------------------------------------------------------------+
| day | 9-10 | 10-11 | 11-12 | 12-1 | 1-2 | 2-3 | 3-4 |
|---------------------------------------------------------------------------
| Monday | DA6210 | DA6220 | DA6010 | | DA6020 | | |
| Tuesday | DA6210 | DA6010 | DA6220 | | DA6020 | | |
| Wednesday | IA6010 | DA6220 | | | DA6020 | | |
| Thursday | IA6010 | | DA6210 | | GC6210 | | |
| Friday | IA6010 | | DA6010 | | GC6210 | | |
| Saturday | DA6210 | | | | | | |
+--------------------------------------------------------------------------+
我想要搜索当天和所有时间的字符串。 对于前者 如果当天是星期四并且代码是DA6220,它应该返回空集,因为字符串在星期四的所有时间段都不存在。
我已经创建了一个SQL查询但它没有按预期工作。 请提供一种方法来做到这一点。
SQl查询: -
SELECT * from `table` where day='Thursday' AND `9-10`='DA6220' OR `10-11`='DA6220' OR `11-12`='DA6220'
OR `12-1`='DA6220' OR `1-2`='DA6220' OR `2-3`='DA6220' OR `3-4`='DA6220'
SELECT * from `table` where day='Thursday' AND (`9-10`='DA6220' OR `10-11`='DA6220' OR `11-12`='DA6220'
OR `12-1`='DA6220' OR `1-2`='DA6220' OR `2-3`='DA6220' OR `3-4`='DA6220')
看起来你的AND首先被评估。 请尝试以上方法
已经给出了问题的答案,但是当我查看您的数据时,我会看到一些可以让您的生活更轻松并增加可能性的东西:您最好创建一个VIEW 。
首先,我稍微修改了你的列名,因为你保留了单词。
介绍你的新朋友myview
cREATE VIEW myview AS
SELECT wkday, '9-10' AS rng, `9-10` AS cd from `mytable`
UNION
SELECT wkday, '10-11' AS rng, `10-11` AS cd from `mytable`
UNION
SELECT wkday, '11-12' AS rng, `11-12` AS cd from `mytable`
UNION
SELECT wkday, '12-1' AS rng, `12-1` AS cd from `mytable`
UNION
SELECT wkday, '1-2' AS rng, `1-2` AS cd from `mytable`
UNION
SELECT wkday, '2-3' AS rng, `2-3` AS cd from `mytable`
UNION
SELECT wkday, '3-4' AS rng, `3-4` AS cd from `mytable`
;
这是针对您的数据库的一次性查询。
您的查看数据是:
SELECT * FROM myview
wkday rng cd
----------------------
Monday 9-10 DA6210
Tuesday 9-10 DA6210
Wednesday 9-10 IA6010
Thursday 9-10 IA6010
Friday 9-10 IA6010
Saturday 9-10 DA6210
Monday 10-11 DA6220
Tuesday 10-11 DA6010
Wednesday 10-11 DA6220
...
创建视图后,原始查询编写起来会更简单:
它变成了这个:
SELEct rng FROM myview WHERE wkday='Thursday' AND cd='DA6220';
没有更多的OR,无需无休止地重复您正在寻找的代码
...如果你想搜索多个代码,它也是花生:
SELEct rng FROM myview WHERE wkday='Thursday' AND cd IN ('DA6220','IA6010');
但是你的新观点很酷,你可以简单地问:
我有代码'DA6220'的日期或范围是多少?
天
SELEct wkday FROM myview WHERE cd='DA6220';
结果:
wkday
----------
Tuesday
Wednesday
Monday
范围
SELEct rng FROM myview WHERE cd='DA6220';
结果:
rng
-----
11-12
10-11
10-11
这是VIEW的典型应用。 它让您的生活更轻松。
阐述我的评论:
SELECT *
FROM `table`
WHERE 0 < LOCATE("DA6220", CONCAT(
`9-10`, " ", `10-11`, " ", `11-12`, " ",
`12-1`, " ", `1-2`, " ", `2-3`, " ", `3-4`
))
这种方法的好处是你不必重复重复搜索字符串。 它可能比OR
版本略慢。
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