SQL返回的值多于应有的值

Question

我想查询所有手工制作的圣诞节，但我得到所有的圣诞节价值。

SELECT * FROM PRODUCT WHERE PROD_CAT = 'Christmas' OR SEC_CAT = 'Christmas' 
AND SUB_CAT = 'Handmade' OR SEC_SUB_CAT = 'Handmade'

如何从圣诞节获得所有手工制作？

Answer 1

你只需要放括号，然后就可以了：

SELECT * FROM PRODUCT WHERE (PROD_CAT = 'Christmas' OR SEC_CAT = 'Christmas') 
AND (SUB_CAT = 'Handmade' OR SEC_SUB_CAT = 'Handmade');

如有任何疑问，请与我联系。

Answer 2

使用括号。我认为你想要：

SELECT *
FROM PRODUCT
WHERE (PROD_CAT = 'Christmas' OR SEC_CAT = 'Christmas') AND
      (SUB_CAT = 'Handmade' OR SEC_SUB_CAT = 'Handmade');

Answer 3

您必须使用括号使sql清楚地显示您想要的内容

SELECT * FROM PRODUCT WHERE (PROD_CAT = 'Christmas' OR SEC_CAT = 'Christmas')
AND (SUB_CAT = 'Handmade' OR SEC_SUB_CAT = 'Handmade')

Answer 4

在某些版本的SQL上，我们可以进一步简化您的查询：

SELECT *
FROM PRODUCT
WHERE 'Christmas' IN (PROD_CAT, SEC_CAT) OR 'Handmade' IN (SUB_CAT, SEC_SUB_CAT);