Question

我有customer和address个表。

查询：

SELECT *
FROM addresses a,
     customers b
WHERE a.id = b.id

返回474条记录

对于这些记录，我想将id customer表格添加到cid表address中。

示例：如果对于第一条记录，customer的id为9且地址的id也为9，那么我想将9插入到地址表的cid列中。

我试过了：

UPDATE addresses a,
       customers b
SET a.cid = b.id
WHERE a.id = b.id

但这似乎不起作用。

Answer 1

这是Postgres UPDATE JOIN格式：

UPDATE address 
SET cid = customers.id
FROM customers 
WHERE customers.id = address.id

以下是其他变体：http://mssql-to-postgresql.blogspot.com/2007/12/updates-in-postgresql-ms-sql-mysql.html

Answer 2

在连接条件中使用表别名：

update addresses a
set cid = b.id 
from customers b 
where a.id = b.id

Answer 3

正式地说，SQL语言不支持UPDATE语句中的JOIN或FROM子句，除非它在子查询中。因此，Hoyle ANSI方法就像

Update addresses
Set cid = (
            Select c.id
            From customers As c
            where c.id = a.id
            )
Where Exists    (
                Select 1
                From customers As C1
                Where C1.id = addresses.id
                )

然而，许多DBMS如Postgres支持在UPDATE语句中使用FROM子句。在许多情况下，您需要包含更新表并将其别名包含在FROM子句中，但我不确定Postgres：

Update addresses
Set cid = c.id
From addresses As a
    Join customers As c
        On c.id = a.id

Answer 4

update addresses set cid=id where id in (select id from customers)

Answer 5

试试这个

UPDATE employee 
set EMPLOYEE.MAIDEN_NAME = 
  (SELECT ADD1 
   FROM EMPS 
   WHERE EMP_CODE=EMPLOYEE.EMP_CODE);
WHERE EMPLOYEE.EMP_CODE >='00' 
AND EMPLOYEE.EMP_CODE <='ZZ';

使用两个表上的连接更新查询

5 个答案: