phpmyadmin SQL query multiple tables

Question

I have two tables.
(1) compressors
(2) crankcase_heaters

I'm trying to create a SQL query to do:

• Select the compressor.VOLTAGE and compressor.WATT of each compressor.PART_NUMBER

• Find the crankcase_heater.PARTNO that has the same voltage and watts.

• Add that value into a new field on the compressor table called "CRANKHTR"

Essentially this query will reproduce my compressors table but will have another 'column' called "CRANKHTR".

I'm completely lost on where to even start with this. I tried using the phpmyadmin SQL Query builder but i have no idea where to begin.

Answer 1

Without seeing the exact data structure, it sounds like you need a simple INNER JOIN:

SELECT 
    `cp`.`VOLTAGE`, 
    `cp`.`WATT`,
    `ch`.`PARTNO` as CRANKHTR
FROM
    `compressor` cp
    INNER JOIN `crankcase_heaters` ch ON ch.VOLTAGE = cp.VOLTAGE AND ch.WATT = cp.WATT