[英]How to add dynamic column to an existing table
I have 2 tables 1st table contains following columns,我有 2 个表第一个表包含以下列,
id code Name
1 c1 chk1
2 c2 chk2
3 c3 chk3
2nd table contains following columns,第二个表包含以下列,
id,Name,Chk1,chk2,Chk3
i have to add the column 'Chk4' into table2 if table1 is updated with value '4,'c4','ch4' dynamically.How to write procedure to perform this?如果 table1 用值 '4,'c4','ch4' 动态更新,我必须将列 'Chk4' 添加到 table2 中。如何编写程序来执行此操作?
i've tried the following procedure but its not working fine.我已经尝试了以下程序,但它不能正常工作。
create proc Add_Check
as
begin
declare @Column varchar(50)
declare @query varchar(255)
declare @query1 varchar(255)
set @Column= (select top 1 QUOTENAME(Name)
from table1 where id=(Select MAX id) from table1))
if exists(select 1 from table1
where Name=@Column)
begin
set @query = 'alter table table2 add ' + @Column + ' Varchar (50)'
set @query1 = 'alter table table2 add ' + @Column + '_CompletedDate Varchar (50)'
exec(@query)
end
end
use this query as procedure.将此查询用作过程。
CREATE PROC ADD_CHECK
AS
BEGIN
DECLARE @COLUMN VARCHAR(50)
DECLARE @QUERY VARCHAR(255)
DECLARE @QUERY1 VARCHAR(255)
SET @COLUMN= (SELECT TOP 1 NAME FROM TABLE1 WHERE ID=(SELECT MAX (ID) FROM TABLE1))
IF EXISTS(SELECT 1 FROM TABLE1 WHERE NAME=@COLUMN)
BEGIN
SET @QUERY = 'ALTER TABLE TABLE2 ADD ' + @COLUMN + ' VARCHAR (50)'
SET @QUERY1 = 'ALTER TABLE TABLE2 ADD ' + @COLUMN + '_COMPLETEDDATE VARCHAR (50)'
EXEC(@QUERY)
END
END
Try this:尝试这个:
CREATE PROCEDURE <procedurename>
AS
BEGIN
DECLARE @COLUMN varchar(10), @SQL Varchar(100);
SELECT @COLUMN = Name FROM Table1
WHERE id = (SELECT MAX(id) FROM Table1)
IF NOT EXISTS(
SELECT COLUMN_NAME
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = 'Table2'
AND COLUMN_NAME = @COLUMN
)
BEGIN
SELECT @SQL =
'ALTER TABLE Table2 ADD '
+@COLUMN+' varchar(10),'
+@COLUMN+'_CompletedDate varchar(50)'
EXECUTE (@SQL)
END
END
Use Triggers as follows:使用触发器如下:
CREATE TRIGGER AddDynamicColumn_to_table2
ON Table1
AFTER INSERT
AS
Exec ('ALTER TABLE Table2 ADD ' + (select name from inserted) + ' Varchar(10)')
GO
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