使用 SET from SELECT 语句不起作用

Question

为什么我不能将变量设置为select查询结果？我收到一个错误

Incorrect syntax near 'tbl'

代码：

DECLARE @AgentNumber INT = 2428
DECLARE @Node HIERARCHYID

SET @Node =  -- this is throwing me syntax error
    (SELECT Node 
     FROM CM.ERGO_HIERARCHY
     WHERE AgentNumber = @AgentNumber) tbl

我知道下面的代码有效，但为什么我不能简单地使用 SET ？

SELECT @Node = Node    -- that works
FROM
    (SELECT Node 
     FROM CM.ERGO_HIERARCHY
     WHERE AgentNumber = @AgentNumber) tbl

Answer 1

试试看：

SET @Node = 
(
SELECT TOP 1 Node 
FROM CM.ERGO_HIERARCHY
WHERE AgentNumber = @AgentNumber
)

使用 SET from SELECT 语句不起作用

Use SET from SELECT statement doesn't work

sql

sql-server

sql-server-2008