Question

I am trying to run a nested query but I am getting this error,

#1241 - Operand should contain 1 column(s)

this is the query that I am trying to run,

SELECT *
FROM `categoryTable`
WHERE `categoryId` NOT
IN (
SELECT `categoryTable`.`categoryId` , `categoryTable`.`categoryTitle` , `userMenuTable`.`menuEntryId`
FROM (
`categoryTable`
)
LEFT JOIN `userMenuTable` ON `categoryTable`.`categoryId` = `userMenuTable`.`categoryId`
WHERE `userMenuTable`.`cookieId` = 'bang4b696152b4869'
)
LIMIT 0 , 30 

Answer 1

5th line should be

SELECT `categoryTable`.`categoryId`

i.e. it should only reference categoryId.
In other words, with the WHERE xyz [NOT] IN (SELECT ... predicate, there should only be one column in the nested select, one corresponding to the “xyz” column but of course not necessarily named the same. The reason is that SQL wouldn’t know which column of the nested query to use for comparing with the “xyz” column; a lesser reason is that the other columns are useless, why bring them in?