Question

我列出了需要从SQL Server中删除的表（大约100 ++）。以下是我将使用的示例代码

IF OBJECT_ID('dbo.DS_Area_TBL', 'U') IS NOT NULL
drop table dbo.DS_Area_TBL
Print 'dbo.DS_Area_TBL has been dropped'

我需要将表名100 ++时间替换为其他表名。如何编写可以自动生成查询列表的动态sql脚本？

Answer 1

DECLARE @SQL NVARCHAR(MAX)

SELECT @SQL = (
    SELECT '
IF OBJECT_ID(''' + obj + ''', ''U'') IS NOT NULL BEGIN
    DROP TABLE ' + obj + '
    PRINT ''' + obj + ' has been dropped''
END
'
    FROM (
        SELECT obj = QUOTENAME(s.name) + '.' + QUOTENAME(o.name)
        FROM sys.objects o
        JOIN sys.schemas s ON o.[schema_id] = s.[schema_id]
        WHERE o.[type] = 'U'
            --AND o.name LIKE 'table%'
            --AND s.name IN ('dbo')
    ) t
    FOR XML PATH(''), TYPE).value('.', 'NVARCHAR(MAX)')

PRINT @SQL
--EXEC sys.sp_executesql @SQL

输出 -

IF OBJECT_ID('[dbo].[user_data]', 'U') IS NOT NULL BEGIN
    DROP TABLE [dbo].[user_data]
    PRINT '[dbo].[user_data] has been dropped'
END

IF OBJECT_ID('[dbo].[formatter_options]', 'U') IS NOT NULL BEGIN
    DROP TABLE [dbo].[formatter_options]
    PRINT '[dbo].[formatter_options] has been dropped'
END

Answer 2

您可以先生成脚本，然后使用动态sql执行：

CREATE TABLE a(a INT);
CREATE TABLE b(a INT);
CREATE TABLE c(a INT);
CREATE TABLE d(a INT);
CREATE TABLE e(a INT);

CREATE TABLE tab(tab_name SYSNAME);   -- here are table names stored
INSERT INTO tab VALUES ('a'),('b'),('c'),('d'),('e');


-- main part
DECLARE @sql NVARCHAR(MAX);

SELECT @sql = STUFF((SELECT ' ' +  FORMATMESSAGE(
'IF OBJECT_ID(''%s'', ''U'') IS NOT NULL 
BEGIN
   DROP TABLE %s;
   PRINT ''%s has been dropped '';
END
', QUOTENAME(tab_name),QUOTENAME(tab_name),QUOTENAME(tab_name))
                   FROM tab
                   FOR XML PATH('')), 1, 1, '');

PRINT @sql;   -- for debug

EXEC [dbo].[sp_executesql]
    @sql;

如果您使用低于2012的SQL Server版本，则需要使用字符串连接FORMATMESSAGE更改+。

您可以通过修改模板轻松地使用自定义架构等扩展此脚本：

'IF OBJECT_ID(''%s'', ''U'') IS NOT NULL 
    BEGIN
       DROP TABLE %s;
       PRINT ''%s has been dropped '';
    END
'

输出：

IF OBJECT_ID('[a]', 'U') IS NOT NULL 
BEGIN
   DROP TABLE [a];
   PRINT '[a] has been dropped ';
END
 IF OBJECT_ID('[b]', 'U') IS NOT NULL 
BEGIN
   DROP TABLE [b];
   PRINT '[b] has been dropped ';
END
 IF OBJECT_ID('[c]', 'U') IS NOT NULL 
BEGIN
   DROP TABLE [c];
   PRINT '[c] has been dropped ';
END
 IF OBJECT_ID('[d]', 'U') IS NOT NULL 
BEGIN
   DROP TABLE [d];
   PRINT '[d] has been dropped ';
END
 IF OBJECT_ID('[e]', 'U') IS NOT NULL 
BEGIN
   DROP TABLE [e];
   PRINT '[e] has been dropped ';
END

修改
工作原理：

XML + STUFF for string concatenation是SQL Server的常用习惯用法，与GROUP_CONCAT中的MySQL类似。您可以将其视为将多个IF BEGIN END块组合成一个字符串的方法。

FORMATMESSAGE会将%s替换为实际的表名（引用以避免SQL注入攻击）

PRINT用于调试以检查生成的查询，可以注释

sp_executesql将执行SQL字符串

动态sql脚本生成drop table语句列表

2 个答案: