Typecast string to integer

I am importing data from a table which has raw feeds in Varchar, I need to import a column in varchar into a string column. I tried using the <column_name>::integer as well as to_number(<column_name>,'9999999') but I am getting errors, as there are a few empty fields, I need to retrieve them as empty or null into the new table.

Solution 1:

Wild guess: If your value is an empty string, you can use NULLIF to replace it for a NULL:

SELECT
    NULLIF(your_value, '')::int

Solution 2:

You can even go one further and restrict on this coalesced field such as, for example:-

SELECT CAST(coalesce(<column>, '0') AS integer) as new_field
from <table>
where CAST(coalesce(<column>, '0') AS integer) >= 10; 

Solution 3:

If you need to treat empty columns as NULLs, try this:

SELECT CAST(nullif(<column>, '') AS integer);

On the other hand, if you do have NULL values that you need to avoid, try:

SELECT CAST(coalesce(<column>, '0') AS integer);

I do agree, error message would help a lot.