我想编写以下 SQL 查询,但是 drop table @temp
和创建表@temp
,这是为什么呢?(使用 SQL Server 2015)
I want to write the following SQL query, however there are incorrect syntax errors with drop table @temp
and
create table @temp
, why is it that? (Using SQL Server 2015)
DECLARE @temp NVARCHAR(10)
SET @temp='sth'
IF OBJECT_ID(@temp, 'U') IS NOT NULL
DROP TABLE @temp
CREATE TABLE @temp
要回答 WHY 的问题,这是很久以前的句法约定.
DROP 语句是这样的:
To answer the question WHY, it is a syntactic convention from days long past.
The DROP statement goes like this:
DROP TABLE MyTable
和不是像这样:
DROP TABLE 'MyTable'
MyTable
是一个标识符,SQL 中的标识符不加引号.并且因为它不使用引号,所以它不接受变量.
MyTable
is an identifier, and identifiers in SQL are not quoted. And because it uses no quotes, it does not accept variables.
也与 WHERE
子句比较:
WHERE MyCol = 'abc'
-- MyCol is not quoted because it is an identifier.
-- 'abc' is quoted because it is a value, and so it can be replaced by a variable.
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