Question

I have been trying to execute this query but it’s not working.

Would appreciate if anyone helps;

SELECT DISTINCT(fld_tech_id) 
FROM tbl_tech_properties 
WHERE fld_tech_category_value_id = 236 
    AND fld_tech_category_value_id = 234

Answer 1

It’s impossible for your WHERE condition to ever match because it is tested for each row in the table and no single row can have fld_tech_category_value_id equal to both 234 and 236 at the same time. Instead you should group by fld_tech_id and check that your group contains two rows.

SELECT fld_tech_id
FROM tbl_tech_properties
WHERE fld_tech_category_value_id IN (234, 236)
GROUP BY fld_tech_id
HAVING COUNT(DISTINCT fld_tech_category_value_id) = 2

See it working online: sqlfiddle