Postgres 13

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CREATE TABLE mytable
    ("col1" text, "col2" text, "col3" text, "minutesintext" text)
;
    
INSERT INTO mytable VALUES
    ('a', 'b', 'c', ' '),
    ('a', 'b', 'c', '11'),
    ('f', 'g', 'e', '98');
3 rows affected

select * from mytable where to_number(minutesintext, '9999') >= 10;
ERROR:  invalid input syntax for type numeric: " "


   select * from mytable 
   where to_number(
       NULLIF(minutesintext, ' '), '9999'
   ) >= 10;


col1
col2
col3
minutesintext


a
b
c
11

f
g
e
98


    select * from mytable 
    where NULLIF(minutesintext, ' ')::int >= 10;


col1
col2
col3
minutesintext


a
b
c
11

f
g
e
98