怎样用sql语句复制表table1到表table2的同时复制主键

Posted 2020-11-23 lonelyxmas

原文:怎样用sql语句复制表table1到表table2的同时复制主键

在从table1表复制到table2的时候，我们会用语句：

select * into table2 from table1

但这个语句并不能在复制数据的同时，复制主键。

下面的代码通过动态语句，来实现在复制数据的同时，也会复制主键：

if OBJECT_ID(‘table1‘) is not null
   drop table table1
go
 
create table table1
(
id  int  ,
idd int,
vvv varchar(100),
primary key (id,idd)  --为了实验在主键有多个字段的情况，所有主键这里有2个字段
)
 
insert into table1
select 1,1,‘a‘ union all
select 1,2,‘b‘ union all
select 2,1,‘a‘ 
go
 
 
declare @old_table_name varchar(30)
declare @new_table_name varchar(30)
declare @is_clustered varchar(10)
declare @sql varchar(1000)
 
set @old_table_name = ‘table1‘;
set @new_table_name = ‘table2‘;
set @is_clustered = ‘‘;
set @sql = ‘‘;
 
select @is_clustered = i.type_desc,
 
       @sql = @sql + ‘,‘ + c.name +
              case when ic.is_descending_key = 0
                        then ‘ asc‘
                   else ‘ desc‘
              end
              
from sys.tables t
inner join sys.indexes i
        on t.object_id = i.object_id
inner join sys.index_columns ic
        on i.object_id = ic.object_id
           and i.index_id = ic.index_id
inner join sys.columns c
        on c.column_id = ic.column_id
           and c.object_id = ic.object_id
where i.is_primary_key = 1
      and t.name = @old_table_name
order by key_ordinal
 
 
 
select @sql = ‘if object_id(‘‘‘ + @new_table_name + ‘‘‘) is not null‘ +
              ‘ drop table ‘ + @new_table_name +‘;‘ +
              ‘select * into ‘ + @new_table_name + 
              ‘ from ‘ + @old_table_name + ‘;‘ +
              
              ‘alter table ‘ + @new_table_name +
              ‘ add primary key ‘ + @is_clustered + 
              ‘(‘ + stuff(@sql,1,1,‘‘) + ‘)‘
 
select @sql  
/*
if object_id(‘table2‘) is not null 
   drop table table2;
select * into table2 from table1;
alter table table2 add primary key CLUSTERED(id asc,idd asc)
*/              
 
exec(@sql)
 
select *
from table2
/*
id	idd	vvv
1	1	a
1	2	b
2	1	a
*/

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