T-SQL Update Trigger

问题:

I'm trying to create the following trigger in SQL Server, but SSMS throws an error and I have no clue what it is. Any thoughts ?

Msg 156, Level 15, State 1, Line 2
Incorrect syntax near the keyword 'trigger'.

Code:

IF NOT EXISTS(SELECT * FROM sys.triggers 
              WHERE object_id = OBJECT_ID(N'[dbo].[trAfterUpdateInfoDoc]'))
    CREATE TRIGGER [dbo].[trAfterUpdateInfoDoc]
    ON [dbo].[InfoDocs]
    AFTER UPDATE
    AS
    BEGIN
        DECLARE @infodoctemplateid INT;
        DECLARE @infodocid INT;
        DECLARE @requireccount FLOAT(2);
        DECLARE @filledcount FLOAT(2);
        DECLARE @pcnt FLOAT(2);

        DECLARE c CURSOR FOR
             SELECT id 
             FROM InfoDocs ifd 
             WHERE exists (SELECT 1 FROM Inserted AS i WHERE i.id = ifd.id)

        OPEN c

        FETCH NEXT FROM c INTO @infodocid

        WHILE @@Fetch_Status = 0 
        BEGIN
            SELECT @infodoctemplateid = InfoDocTemplateId 
            FROM InfoDocs 
            WHERE id = @infodocid;

            SELECT @requireccount = COUNT(*) 
            FROM InfoDocTemplateFields 
            WHERE InfoDocTemplateId = @infodoctemplateid 
              AND IsRequired = 1;

            IF (@requireccount = 0)
            BEGIN
                set @pcnt = 100;
            END
            ELSE
            BEGIN
                select @filledcount = count(*) from InfoDocFields 
                where InfoDocId = @infodocid 
                and InfoDocTemplateFieldId in (select id from InfoDocTemplateFields where InfoDocTemplateId = @infodoctemplateid and IsRequired = 1)
                and (BooleanValue is not null or (StringValue is not null and StringValue <> '') or IntValue is not null or DateValue is not null)

                set @pcnt = @filledcount / @requireccount * 100.0;
            END
            update InfoDocs set PercentageCompleted = @pcnt Where id = @infodocid;

            Fetch next From c into @infodocid
        End
    Close c
    Deallocate c
END

回答1:

Create Trigger (Limitations section) must be the first statement in a batch, so you can't use the IF exists check before it.

In SQL Server 2016 SP1 onwards, you can use CREATE OR ALTER TRIGGER... for the same behaviour.

Pre-SQL Server 2016 SP1, there's some suggestions here

I also second Zohar's comment that putting this logic into a trigger could well cause you many performance issues & possibly hard to track down unexpected behaviour/bugs.

回答2:

Anytime a SQL object like a trigger is created, it needs to be the only object created in the batch. A batch is terminated by the keyword GO.

Try refactoring your code to fit this general structure and see if it works:

IF OBJECT_ID(N'[dbo].[trAfterUpdateInfoDoc]') IS NOT NULL
    DROP TRIGGER [dbo].[trAfterUpdateInfoDoc]
GO

CREATE TRIGGER [dbo].[trAfterUpdateInfoDoc]
ON [dbo].[InfoDocs]
AFTER UPDATE
AS
BEGIN
    --PLACE CODE HERE
END
GO