选择值不存在的 SQL

Question

I have a two columns product_id and category_id . I want to select all product_id that don't have the category_id = 90

I use this query, but it returns null. What am I doing wrong?

SELECT * 
FROM  `oc_product_to_category` 
WHERE NOT EXISTS (
  SELECT * 
  FROM  `oc_product_to_category` 
  WHERE category_id = 90
)

Answer 1

You aren't correlating the inner and outer queries. If there's at least one product with category_id = 90 the inner query will return some rows, and thus the NOT EXISTS condition will always be false, and the outer query will return no rows. You need to add a condition to specify the inner query and the outer query refer to the same product:

SELECT * 
FROM  `oc_product_to_category` a
WHERE NOT EXISTS (
  SELECT * 
  FROM   `oc_product_to_category` b
  WHERE  category_id = 90 AND
         a.product_id = b.product_id -- Here!
)

Answer 2

You can query the oc_product table and check for products that do not have a corresponding entry in the oc_product_to_category table with category_id equal to 90.

SELECT *
FROM `oc_product`
WHERE product_id NOT IN
    (SELECT product_id
    FROM `oc_product_to_category`
    WHERE category_id = 90)

Answer 3

Try This

SELECT * 
FROM  `oc_product_to_category` 
WHERE category_id <> **90**

Answer 4

try this:

SELECT * 
FROM  `oc_product_to_category`
WHERE category_id <> 90

Answer 5

SELECT * 
FROM  `oc_product_to_category` where product_id NOT IN (SELECT product_id
FROM  `oc_product_to_category where category_id = 90)

Answer 6

your query should be like this

SELECT * 
FROM  `oc_product_to_category` m 
WHERE NOT EXISTS (
SELECT * 
FROM  `oc_product_to_category` 
WHERE m.category_id = 90
)

you can get many ways those result like

SELECT * 
FROM  `oc_product_to_category` 
WHERE category_id <> 90




SELECT * 
FROM  `oc_product_to_category` 
WHERE category_id != 90


SELECT * 
FROM  `oc_product_to_category` 
having category_id <> 90



SELECT * 
FROM  `oc_product_to_category` 
WHERE category_id NOT IN
(SELECT * 
FROM  `oc_product_to_category` 
WHERE category_id = 90)

Answer 7

SELECT * FROM oc_product_to_category WHERE category_id <> 90 ;

Answer 8

Try this

SELECT * 
FROM your_Name 
WHERE category_id NOT LIKE '90'

Answer 9

Try:

SELECT * 
FROM  oc_product_to_category 
WHERE category_id not in ('90')

Answer 10

Try this

SELECT * FROM oc_product_to_category where category_id != 90

(OR)

SELECT * FROM oc_product_to_category where category_id <> 90