Laravel 语法获取具有不同结果的查询

Question

我有两个 MySQL 表：

+-----------+    +-----------+
| id.Table1 |    | id.Table2 |
+-----------+    +-----------+
|         1 |    |         2 |
|         2 |    |         3 |
|         3 |    |         4 |
|         4 |    +-----------+
|         5 |
+-----------+

我想得到一个带有这个结果的查询：

+-----------+
| id.Table1 |
+-----------+
|         1 |
|         5 |
+-----------+

我该怎么做？

Answer 1

一种方法是使用NOT IN子句：

SELECT ID FROM TABLE1 WHERE ID NOT IN (SELECT ID FROM TABLE2)

Answer 2

尝试NOT EXISTS

SELECT ID FROM TABLE1 as a WHERE NOT EXISTS (SELECT ID FROM TABLE2 as b where a.ID=b.ID)

Answer 3

您可以通过使用LEFT JOIN和NULL检查来实现结果。 工作查询是：

SELECT T1.Id
FROM Table1 T1
LEFT JOIN Table2 T2 ON T2.Id = T1.Id
WHERE T2.Id IS NULL