Redshift LIKE列值，带％

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问题描述

我有一列，它是用逗号分隔的值字符串.我想加入另一个只有一个值的表.在进行红移时，如何在比较中注入'％'来进行LIKE运算符?

I have a column that is a comma separated string of values. I want to join another table that only has one of the values. On redshift, how can I do a LIKE operator with '%' injected into the comparison?

例如:

TableA:values_col ='abc，def'

TableA: values_col = 'abc, def'

TableB:value_col ='def'

TableB: value_col = 'def'

SELECT *
FROM TableA a
JOIN TableB b ON b.value_col LIKE '%' || a.values_col || '%'

上面的concat似乎不起作用.任何建议，将不胜感激.谢谢.

The above concat doesn't seem to work. Any suggestions would be appreciated. Thanks.

推荐答案

您将获得出色的性能.您应该修复您的数据结构.但是如果必须的话，这应该可以工作:

You will get awful performance. You should fix your data structure. But if you have to, then this should work:

SELECT *
FROM TableA a JOIN
     TableB b
     ON ',' || a.values_col || ',' LIKE '%,' || b.value_col || ',%';

如果值之间可以包含逗号，则逗号很重要.更重要的是，like需要正确顺序的操作数.

The commas are important if your values can contain each other. More importantly, the like needs the operands in the right order.

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