将查询更改为更新

Question

我有以下疑问：

SELECT        UsersAccountLink.UserId, Customer.Account.AccountNumber, Web.Customer.Name, Web.Customer.Street, UsersAccountLink.AccountId
FROM            UsersAccountLink INNER JOIN
                         Web.Customer ON UsersAccountLink.AccountId = Web.Customer.AccountId LEFT OUTER JOIN
                         Customer.Account ON UsersAccountLink.AccountId = Customer.Account.AccountId
WHERE        (Customer.Account.AccountNumber IS NULL)
Order by Name

我需要将选择更改为并更新。如果 Customer.Account.AcountNumber 为 NULL，我需要将 UsersAccountLink.UserId 设置为空 guid。

我怀疑我有这个权利，所以这就是我想出的：

UPDATE
    UsersAccountLink
SET
    UsersAccountLink.AccountId = '00000000-0000-0000-0000-000000000000'
FROM            
    UsersAccountLink 
INNER JOIN
    Web.Customer ON UsersAccountLink.AccountId = Web.Customer.AccountId 
LEFT OUTER JOIN
    Customer.Account ON UsersAccountLink.AccountId = Customer.Account.AccountId
WHERE        
    (Customer.Account.AccountNumber IS NULL)

我基于这篇帖子How do I UPDATE from a SELECT in SQL Server?

UPDATE
    Table
SET
    Table.col1 = other_table.col1,
    Table.col2 = other_table.col2
FROM
    Table
INNER JOIN
    other_table
ON
    Table.id = other_table.id

两个问题：

1. 有没有办法在实际运行之前测试运行查询，例如更新或删除？
2. 我是否正确地将其转换为更新？

谢谢！

Answer 1

This is what you can do to test

insert a select statment here to view the record(s) before the insert
BEgin tran
UPDATE
    UsersAccountLink
SET
    UsersAccountLink.AccountId = '00000000-0000-0000-0000-000000000000'
FROM            
    UsersAccountLink 
INNER JOIN
    Web.Customer ON UsersAccountLink.AccountId = Web.Customer.AccountId 
LEFT OUTER JOIN
    Customer.Account ON UsersAccountLink.AccountId = Customer.Account.AccountId
WHERE        
    (Customer.Account.AccountNumber IS NULL)

insert a select statment here to view the record(s) after the insert
Rollback tran

最好还是在 dev 而不是 prod 上这样做。在您遇到的特定情况下，我还想测试如果稍后在不同的记录上运行会发生什么。或者至少检查以确保您的 accountid 没有唯一索引。

我也喜欢这样做：

UPDATE
    UsersAccountLink
SET
    UsersAccountLink.AccountId = '00000000-0000-0000-0000-000000000000'
--SELECT * (or you can specify columns you specifically want to see)

FROM            
    UsersAccountLink 
INNER JOIN
    Web.Customer ON UsersAccountLink.AccountId = Web.Customer.AccountId 
LEFT OUTER JOIN
    Customer.Account ON UsersAccountLink.AccountId = Customer.Account.AccountId
WHERE        
    (Customer.Account.AccountNumber IS NULL)

这使您可以通过运行带注释的选择轻松检查。它还可以轻松地将选择更改为更新，方法是编写选择，然后将更新信息放在它上面并在 FROM statmenet 之前评论选择中的所有内容。