How can I do a BEFORE UPDATED trigger with sql server

Question

I m using Sqlserver express and I can t do before updated trigger  There s a other way to do that

User · Answer

Can t be sure if this applied to SQL Server Express  but you can still access the  before  data even if your trigger is happening AFTER the update  You need to read the data from either the deleted or inserted table that is created on the fly when the table is changed  This is essentially what  Stamen says  but I still needed to explore further to understand that  helpful   answer      The deleted table stores copies of the affected rows during DELETE and   UPDATE statements  During the execution of a DELETE or UPDATE   statement  rows are deleted from the trigger table and transferred to   the deleted table         The inserted table stores copies of the affected rows during INSERT   and UPDATE statements  During an insert or update transaction  new   rows are added to both the inserted table and the trigger table         https   msdn microsoft com en-us library ms191300 aspx   So you can create your trigger to read data from one of those tables  e g   CREATE TRIGGER  lt TriggerName gt  ON  lt TableName gt  AFTER UPDATE AS   BEGIN     INSERT INTO  lt HistoryTable gt     lt columns    gt   DateChanged       SELECT  lt columns    gt   getdate       FROM deleted    END    My example is based on the one here   http   www seemoredata com en showthread php 134-Example-of-BEFORE-UPDATE-trigger-in-Sql-Server-good-for-Type-2-dimension-table-updates  sql-server triggers

User · Answer

The updated or deleted values are stored in DELETED  we can get it by the below method in trigger Full example  CREATE TRIGGER PRODUCT UPDATE ON PRODUCTS FOR UPDATE  AS BEGIN DECLARE  PRODUCT NAME OLD VARCHAR 100  DECLARE  PRODUCT NAME NEW VARCHAR 100   SELECT  PRODUCT NAME OLD   product name from DELETED SELECT  PRODUCT NAME NEW   product name from INSERTED  END

User · Answer

Remember that when you use an instead trigger  it will not commit the insert unless you specifically tell it to in the trigger  Instead of really means do this instead of what you normally do  so none of the normal insert actions would happen

User · Answer

To do a BEFORE UPDATE in SQL Server I use a trick  I do a false update of the record  UPDATE Table SET Field   Field   in such way I get the previous image of the record

User · Answer

MSSQL does not support BEFORE triggers   The closest you have is INSTEAD OF triggers but their behavior is different to that of BEFORE triggers in MySQL   You can learn more about them here  and note that INSTEAD OF triggers  Specifies that the trigger is executed instead of the triggering SQL statement  thus overriding the actions of the triggering statements    Thus  actions on the update may not take place if the trigger is not properly written handled   Cascading actions are also affected   You may instead want to use a different approach to what you are trying to achieve

User · Answer

All  normal  triggers in SQL Server are  AFTER      triggers  There are no  BEFORE      triggers   To do something before an update  check out INSTEAD OF UPDATE Triggers

User · Answer

It is true that there aren t  before triggers  in MSSQL  However  you could still track the changes that were made on the table  by using the  inserted  and  deleted  tables together  When an update causes the trigger to fire  the  inserted  table stores the new values and the  deleted  table stores the old values  Once having this info  you could relatively easy simulate the  before trigger  behaviour

User · Answer

T-SQL supports only AFTER and INSTEAD OF triggers  it does not feature a BEFORE trigger  as found in some other RDBMSs   I believe you will want to use an INSTEAD OF trigger

User · Answer

Full example   CREATE TRIGGER  dbo   trig 020 Original 010 010 Gamechanger     ON   dbo   T Original     AFTER UPDATE AS  BEGIN     -- SET NOCOUNT ON added to prevent extra result sets from     -- interfering with SELECT statements      SET NOCOUNT ON      DECLARE  Old Gamechanger int      DECLARE  New Gamechanger int       -- Insert statements for trigger here     SELECT  Old Gamechanger   Gamechanger from DELETED      SELECT  New Gamechanger   Gamechanger from INSERTED       IF  Old Gamechanger     New Gamechanger          BEGIN              INSERT INTO  dbo  T History ChangeDate  Reason  Callcenter ID  Old Gamechanger  New Gamechanger              SELECT GETDATE     Time for a change   Callcenter ID   Old Gamechanger   New Gamechanger                 FROM deleted                        END  END

[sql] How can I do a BEFORE UPDATED trigger with sql server?

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