Use triggers to dynamically add columns

Source: Internet
Author: User

Create Table TA (number INT)

Create trigger test_tr on TA
For insert
Declare @ number int, @ SQL varchar (4000), @ sql1 varchar (4000), @ I int
Declare Roy cursor
For select * From inserted
Open Roy
Fetch next from Roy into @ number
While @ fetch_status = 0
If exists (select 1 from sysobjects where name = 'tb' and xtype = 'U ')
Select @ I = max (colid) + 1 from syscolumns where id = object_id ('tb ')
Set @ SQL = n' alter table tb add C' + Cast (@ I as varchar) + 'int null'
Set @ sql1 = n' update TB set C' + Cast (@ I as varchar) + '=' + Cast (@ number as varchar)
-- Print @ SQL
-- Print @ sql1
Exec (@ SQL)
Exec (@ sql1)
Set @ SQL = n' CREATE TABLE Tb (C1 INT )'
Set @ sql1 = n' insert TB select C1 = '+ Cast (@ number as varchar)
Exec (@ SQL)
Exec (@ sql1)
Fetch next from Roy into @ number
Close Roy
Deallocate Roy
Insert Ta
Select 10 Union all
Select 13 Union all
Select 18 Union all
Select 26
Select * from TB

C1 C2 C3 C4
10 13 18 26

(The number of affected rows is 1)

-- Drop table Ta, TB

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