在 SQL 服务器中使用多个 NOT IN

Question

我有两个这样的 table：

Table 1: City - 主键: ID_City:

| City      | ID_City | ID_State|
+-----------+---------+---------+
| Chennai   | 1       | 2       |
| Bengaluru | 2       | 1       |
| Lucknow   | 3       | 3       |
|   .       | .       | .       |
|   .       | .       | .       |

我正在向现有数据库添加新城市，同时使用 NOT IN 检查现有城市。 @table 看起来像这样：

Table 1: @table

| City      | ID_State|Zip_Code|
+-----------+---------+--------+
| Chennai   | 2       |00001   |
| Chennai   | 2       |00002   |
| Chennai   | 2       |00003   |
| Bengaluru | 1       |10011   |
| Bengaluru | 1       |10012   |
| Bengaluru | 1       |10013   |
| Lucknow   | 3       |20001   |
| Mysore    | 4       |50001   |
| Mysore    | 4       |50002   |
| Mysore    | 4       |50003   |
|   .       | .       | .      |

预期结果：

查询应该检查已经存在的城市并过滤掉那些不应添加的城市。（这是使用 NOT IN 完成的）
另外，如果有多个相同城市的行，则不应添加多个相同城市的副本。例如：查询应该只添加一行 City- 'Mysore' 而不是三行

我执行的查询：

SELECT 
    City, id_state 
FROM 
    @table
WHERE 
    City NOT IN (SELECT City FROM City WHERE City IS NOT NULL)
    AND id_state NOT IN (SELECT id_state FROM City WHERE id_state IS NOT NULL)

Answer 1

您可以使用 select 不同的：

SELECT distinct City, id_state FROM @table WHERE City 
NOT IN (SELECT City FROM City WHERE City IS NOT Null) AND id_state NOT 
IN (SELECT id_state FROM City WHERE id_state IS NOT Null)

Answer 2

一个城市名称可以属于多个州，因此您需要检查这两种组合。

我觉得下面的查询应该会给你想要的输出。

SELECT DISTINCT City, id_state 
FROM @table T1
WHERE NOT EXISTS
(
 SELECT 1 FROM City C WHERE C.City = T1.City AND T.id_state = C.id_state  
)

Answer 3

考虑使用 NOT EXISTS 而不是 NOT IN：

SELECT DISTINCT City
,               id_state
FROM   @table t1
WHERE  NOT EXISTS (   SELECT City
                      FROM   City t2
                      WHERE  t1.City = t2.City
                             AND t1.id_state = t2.id_state 
                             );

原因：

一个子句可以定义多个谓词，所以需要有多个NOT IN
从性能的角度来看，它的查询计划比 NOT IN 更快。

Answer 4

您可以使用 NOT IN 和 NOT EXISTS 实现此目的

不在：

SELECT DISTINCT t.City, t.id_state 
  FROM @table t 
 WHERE City NOT IN (SELECT c.City  FROM City WHERE c.city = t.city AND c.id_state = t.id_state)

不存在：

SELECT DISTINCT t.City, t.id_state 
  FROM @table t 
 WHERE NOT EXISTS  (SELECT TOP 1 c.city  FROM City WHERE c.city = t.city AND c.id_state = t.id_state)

NOT EXISTS 比 NOT IN 好。也不需要多个 NOT IN。

在 SQL 服务器中使用多个 NOT IN

Using multiple NOT IN in SQL Server

sql

sql-server

notin