Correct posture for SQL dynamic add field

How do I add fields to a specified table dynamically?

First, create a table "Tbl_autofileds"

(tablename table name, fieldname field name, datatype data type, length isnull if NULL is allowed)

Second, create a table trigger for "tbl_autofileds"

SETAnsi_nulls Ongoset QUOTED_IDENTIFIER Ongo
-- =============================================--author:< Author >--Create Date: <20160320 date,,>--description:< adding columns to the corresponding table when the table is inserting data >
-- =============================================ALTER TRIGGER [dbo].[Filed_auto]    on  [dbo].[tbl_autofileds]  for Insert  as DECLARE@tb_Name varchar( -), @coloun varchar( -),@datatype varchar( -),@length varchar( +),@isnull varchar(Ten),@sql varchar( $) Beginset NOCOUNT on; Select @tb_Name=Tabld_name,@coloun=FieldName,@datatype=DataType@length=[length],@isnull=[IsNull]  frominsertedif  not exists(Select *  fromsyscolumnswhereId=object_id(@tb_Name) andName=@coloun)   begin  Set @sql='ALTER Table'+@tb_Name+'Add'+@coloun+' '+@datatype+'('+@length+') '+@isnullexec(@sql)  End

Third, add content to the table, while adding columns to the corresponding table

Inserting content into the Tbl_autofields table triggers a trigger to dynamically add fields to the specified table:

Insert  into Values ('tbl_test','MyField','nvarchar  ','+ ','null');

We added a field myfield with a data type of nvarchar (200) to the Tbl_test table.

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Correct posture for SQL dynamic add field