无法弄清楚这个 SQL CASE 的问题

Question

CASE
WHEN CAST(a.category AS VARCHAR) like '%jumpsuits%'   THEN CAST(a.google_product_category AS VARCHAR) = 'Apparel & Accessories > Clothing > One-Pieces > Jumpsuits & Rompers'
WHEN CAST(a.category AS VARCHAR) like '%knitwear%'    THEN CAST(a.google_product_category AS VARCHAR) = 'Apparel & Accessories > Clothing > Dresses'
WHEN CAST(a.category AS VARCHAR) like '%lounge wear%' THEN CAST(a.google_product_category AS VARCHAR) = 'Apparel & Accessories > Clothing > Shirts & Tops'
ELSE CAST(a.google_product_category AS VARCHAR) END as google_product_category

我面临的问题是：“SYNTAX_ERROR: line 7:6: All CASE results must be the same type: boolean”

我还在之前的子查询中加入了该表，将其转换为 varchar，因此应该没有任何问题。

有人有什么想法吗？

对于上下文，我正在尝试填充一个字段，该字段将返回一个空白，该类别就像我的“喜欢”其他任何我希望它保持原样的东西。

非常感谢

Answer 1

您的CASE 具有返回不同数据类型的表达式，这是不允许的。如果您只是尝试根据category 列更新google_product_category，请尝试以下操作：

数据样本

CREATE TEMPORARY TABLE t (category TEXT, google_product_category TEXT);
INSERT INTO t VALUES ('Jumpsuit'),('kniTweaR'),('lounge WEAR');

查询

SELECT category,
  CASE 
    WHEN category ILIKE '%jumpsuit%' 
      THEN 'Apparel & Accessories > Clothing > One-Pieces > Jumpsuits & Rompers'
    WHEN category ILIKE '%knitwear%' 
      THEN 'Apparel & Accessories > Clothing > Dresses'
    WHEN category ILIKE '%lounge wear%' 
      THEN 'Apparel & Accessories > Clothing > Shirts & Tops'
  END
FROM t;

  category   |                                case                                 
-------------+---------------------------------------------------------------------
 Jumpsuit    | Apparel & Accessories > Clothing > One-Pieces > Jumpsuits & Rompers
 kniTweaR    | Apparel & Accessories > Clothing > Dresses
 lounge WEAR | Apparel & Accessories > Clothing > Shirts & Tops
(3 Zeilen)