SQL Server中查询中的动态表名和变量名 [英] Dynamic table name and variable name in query in SQL Server

问题描述

我正在尝试使用动态表名和日期创建一个可以从 Python 运行的查询.在此过程中，我在 SSMS 中尝试了以下查询，但它产生了错误消息.如何使用变量作为表名和日期，并使查询工作?

I am trying to make a query that I can run from Python with dynamic table name and date. In the process of this, I have tried the following query in SSMS, but it is producing an error message. How can I use variables for table name and a date, and get the query to work?

DECLARE @table_name VARCHAR(50)='table_name';
DECLARE @valid_to datetime = getdate();

EXEC('UPDATE '+ @table_name + '
SET valid_flag = 0, 
valid_to = '+ @valid_to +'
where valid_flag=1')

我收到以下错误消息:

消息 102，级别 15，状态 1，第 3 行
'10' 附近的语法不正确

Msg 102, Level 15, State 1, Line 3
Incorrect syntax near '10'

推荐答案

使用 sp_executesql 和参数:

DECLARE @table_name VARCHAR(50) = 'table_name';
DECLARE @valid_to datetime = getdate();

DECLARE @sql NVARCHAR(max) = N'
UPDATE '+ @table_name + N'
    SET valid_flag = 0, 
        valid_to = @valid_to
    WHERE valid_flag = 1
';

EXEC sp_executesql @sql, N'@valid_to datetime', @valid_to=@valid_to;

正如 Larnu 推荐的评论:

As recommended by Larnu a comment:

DECLARE @table_name sysname = 'table_name';
DECLARE @valid_to datetime = getdate();

DECLARE @sql NVARCHAR(max) = N'
UPDATE '+ QUOTENAME(@table_name) + N'
    SET valid_flag = 0, 
        valid_to = @valid_to
    WHERE valid_flag = 1
';

EXEC sp_executesql @sql, N'@valid_to datetime', @valid_to=@valid_to;

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