my sql operand should contain 1 column in my database

Question

when i execute this query

SELECT 
    tbcategory.CATEGORY_ID,
    tbcategory.VENDOR_ID,
    tbcategory.CATEGORY_NAME,
    tbsubcategory.SUB_CATEGORY_ID,
    tbsubcategory.SUB_CATEGORY_NAME,
    PRODUCT_ID,
    PRODUCT_NAME,
    PRODUCT_DESC,
    GENERAL_PRICE,
    RESELLER_PRICE,
    SPECIAL_PRICE,
    PRODUCT_SHOT_DESC,
    MANUFACTURE_PART_NUM,
    SKU_ID,
    IMAGE
FROM
    tbproduct,
    tbcategory,
    tbsubcategory
WHERE
    tbsubcategory.CATEGORY_ID = tbcategory.CATEGORY_ID
        AND tbsubcategory.SUB_CATEGORY_ID = tbproduct.SUBCATEGORY_ID
        AND tbcategory.CATEGORY_ID IN (SELECT 
            tbcategory . *
        FROM
            tbcategory
                JOIN
            tbcustomer ON FIND_IN_SET(tbcategory.CATEGORY_ID,
                    tbcustomer.ASSIGNED_CATEGORIES)
        WHERE
            USER_NAME = 'clark' AND password = '420' UNION SELECT 
            CATEGORY_ID
        FROM
            tbcategory,
            tbvendor
        WHERE
            tbvendor.USER_NAME = 'wong'
                AND tbvendor.PASSWORD = '143'
                AND tbvendor.VENDOR_ID = tbcategory.VENDOR_ID)
ORDER BY tbcategory.CATEGORY_ID , tbsubcategory.SUB_CATEGORY_ID , tbproduct.PRODUCT_ID;

am getting Error Code : 1241 Operand should contain 1 column(s)

Answer 1

In your subquery you should select one column in order to match with category id

AND tbcategory.CATEGORY_ID IN 
  (SELECT 
    tbcategory.CATEGORY_ID <----- here 
  FROM
    tbcategory 
    JOIN tbcustomer 
      ON FIND_IN_SET(
        tbcategory.CATEGORY_ID,
        tbcustomer.ASSIGNED_CATEGORIES
      ) .....