I try to get columns from my database with a singel SELECT, but I stuck.
I have 3 tables like:
1) categories (serial,cat)
2) manufacturers (serial,m_name)
3) products (serial,category,manufacturer,p_name)
where the "category" and "manufacturer" are numerical IDs from the two tables above.
So I like to replace the numerical IDs with the appropriated values, mean
SELECT * FROM products WHERE category IN (SELECT categories.cat FROM categories WHERE categories.serial==products.category);
But I get:
ERROR: operator does not exist: integer==integer LINE1: ...gories.cat FROM categories WHERE categories.serial==products.category); ^ Hmm, "serial" is an "integer" and the "category" and "manufacturer" too.