MySQL CASE表达式简单使用

CASE value   
    WHEN [compare_value] THEN result   
    [WHEN [compare_value] THEN result ...]   
    [ELSE result]   
END  

# 根据类别id,确定对应的主营类型
select
  (
    CASE category_id
      WHEN 35 THEN '生鲜果蔬'
      WHEN 36 THEN '休闲零食'
      WHEN 37 THEN '蛋糕烘焙'
      WHEN 38 THEN '茶饮酒水'
      WHEN 39 THEN '滋补保健'
      WHEN 40 THEN '粮油米面'
      WHEN 41 THEN '综合食品'
      WHEN 26 THEN '汽车养护'
      WHEN 31 THEN '充值缴费'
      ELSE ' '
    END
  ) as ’ 商 品 类 目 ‘
FROM
  shopxx.xx_platform;

CASE   
    WHEN [condition] THEN result   
    [WHEN [condition] THEN result ...]   
    [ELSE result]   
END  

# 根据商品类型不同，描述信息存放的字段也不一样
SELECT id,id,goods,organize supplier_id,productType,is_list,is_marketable,
  (
    CASE
      WHEN productType = 9 OR productType = 11 THEN detail_image #虚拟商品
      ELSE product_desc # 实物商品
    END
  ) spu_describe
FROM
  xx_product
WHERE
  pfid = 20000
  AND del_state IS NULL;# 删除状态字段为NULL代表未删除