PostgreSQL string Function--position

Today, the interception function is needed to deal with the redundancy of database field content that was generated by a bug.

I looked through the Internet and found this string function position.

POSITION (substr in str)

POSITION (substr in str) are a synonym for LOCATE (SUBSTR,STR).

Here's the official document address.

Https://www.postgresql.org/docs/9.3/static/functions-string.html

When you use it, you want to remove the underline from the field. As you know with SQL, the underscore is a placeholder, and if you want to find an underscore, you need to escape it.

However, when the position substr this parameter bit, it does not need to be escaped. Surprised me a bit.

This substr should be a definite string and cannot have any placeholders. I learned it!

PostgreSQL string Function--position