PostgreSQL column 'foo' does not exist

Question

I have a table that has 20 integer columns and 1 text column named \'foo\'

If I run query:

SELECT * from table_name where foo is NULL

Answer 1

If for some reason you have created a mixed-case or upper-case column name, you need to quote it, or get this error:

test=> create table moo("FOO" int);
CREATE TABLE
test=> select * from moo;
 FOO 
-----
(0 rows)
test=> select "foo" from moo;
ERROR:  column "foo" does not exist
LINE 1: select "foo" from moo;
               ^
test=> _

Note how the error message gives the case in quotes.