Sql – Postgresql SELECT if string contains

postgresqlsql

So I have a in my Postgresql:

TAG_TABLE
==========================
id            tag_name       
--------------------------
1             aaa
2             bbb
3             ccc

To simplify my problem,
What I want to do is SELECT 'id' from TAG_TABLE when a string "aaaaaaaa" contains the 'tag_name'.
So ideally, it should only return "1", which is the ID for tag name 'aaa'

This is what I am doing so far:

SELECT id FROM TAG_TABLE WHERE 'aaaaaaaaaaa' LIKE '%tag_name%'

But obviously, this does not work, since the postgres thinks that '%tag_name%' means a pattern containing the substring 'tag_name' instead of the actual data value under that column.

How do I pass the tag_name to the pattern??

Best Answer

You should use 'tag_name' outside of quotes; then its interpreted as a field of the record. Concatenate using '||' with the literal percent signs:

SELECT id FROM TAG_TABLE WHERE 'aaaaaaaa' LIKE '%' || tag_name || '%';
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