MYSQL IF字段包含这使得其他字段

Question

我ITEM在table1中有一个字段.如果ITEM包含%USED-%(USED-)那么我想做它TIER1 Used Restaurant Equipment所以它相应地分组.

这是我目前的陈述,我怎么能用IF或实现上述CASE？

select 
    CT.TIER1, CT.TIER2
from
    trx.table1 MT
        LEFT JOIN
    trx.table2 CT1 ON MT.ITEM = CT1.ITEM
        LEFT JOIN
    trx.table3 CT ON CT1.WEB_NUM = CT.WEBNUMBER
GROUP BY CT.TIER1
LIMIT 0 , 15

电流输出:

TIER1                   TIER2
NULL                    NULL
Business Type           Ice Cream Equipment
Chinese Food Equipment  Ricers
Concession Equipment    Concession Accessories
Cooking Equipment       Fryers
Food Preparation        Food Preparation Supplies
Food Storage            Storage Racks
Food Warming Equipment  Hot Food Wells

我希望仍然有一些NULLTier1和Tier2,但我希望它也将TIER1显示为"二手餐厅设备",类似于:

TIER1                      TIER2
NULL                       NULL
Used Restaurant Equipment  NULL
Business Type              Ice Cream Equipment
Chinese Food Equipment     Ricers
Concession Equipment       Concession 

Answer 1

这应该是你正在寻找的:

   SELECT
       IF (MT.ITEM LIKE '%USED-%', 'Used Restaurant Equipment', CT.TIER1) AS TIER1,
       CT.TIER2
   FROM
       trx.table1 MT
           LEFT JOIN
       trx.table2 CT1 ON MT.ITEM = CT1.ITEM
           LEFT JOIN
       trx.table3 CT ON CT1.WEB_NUM = CT.WEBNUMBER
   GROUP BY
       IF (MT.ITEM LIKE '%USED-%', 'Used Restaurant Equipment', CT.TIER1)
   LIMIT 0 , 15