In Postrgesql, I created a function to check a column value is number or not. Its a simple function.
Now execute the function:
CREATE OR REPLACE FUNCTION is_number(prm_str text) RETURNS BOOLEAN AS $$
DECLARE
v_return BOOLEAN;
BEGIN
IF regexp_matches(prm_str,E'^-*[[:digit:]]+\.?[[:digit:]]+$') is not null
THEN
v_return = TRUE;
ELSE
v_return = FALSE;
END IF;
RETURN v_return;
END;
$$ LANGUAGE 'plpgsql';
Now execute the function:
SELECT *, is_number(col_val) as isNumber FROM table;