[SQL] Extracting valid timestamps in SQL

I am working with Netezza sql. I have a table (my_table). For col_1, I only want to extract rows that are in the following format: 2020-01-01 12:00:00 and col_2 is only numbers

I am trying to do this with regexp_extract:

SELECT *
FROM my_table
WHERE regexp_extract(col_1,
'^[0-9]{4}-[0-9]{2}-[0-9]{2} [0-9]{2}:[0-9]{2}:[0-9]{2}$')
IS NOT NULL;

SELECT *
FROM my_table
WHERE regexp_like(col_2, '^[0-9]+$');


Is there a more uniform way to do this such that it can work on multiple different versions of SQL?

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