Why does using an Underscore character in a LIKE filter give me all the results?

Question

I wrote the below SQL query with a LIKE condition:

SELECT * FROM Manager
WHERE managerid LIKE \'_%\'
AND managername LIKE \'%_%\'

Answer 1

In case people are searching how to do it in BigQuery:

• An underscore "_" matches a single character or byte.

• You can escape "\", "_", or "%" using two backslashes. For example, "\%". If you are using raw strings, only a single backslash is required. For example, r"\%".

WHERE mycolumn LIKE '%\\_%'

Source: https://cloud.google.com/bigquery/docs/reference/standard-sql/operators