japogs007ph japogs007ph - 5 months ago 8
SQL Question

Cannot perform multi-row insert on trigger when inserting record with unique id

Here is my trigger:

ALTER TRIGGER DONORINFO_INSERT
ON [dbo].[DONORINFO] INSTEAD OF INSERT
AS
DECLARE @sequence AS VARCHAR(50) = ''
DECLARE @tranLen VARCHAR(10)

SET @sequence = (SELECT TOP 1 SUBSTRING([DONORID], 3, 8)
FROM [dbo].[DONORINFO]
ORDER BY [DONORID] DESC)

IF (@sequence IS NULL OR @sequence = '')
BEGIN
SELECT @sequence = REPLICATE('0', 7 ) + '1'
END
ELSE
BEGIN
SELECT @tranLen = LEN(@sequence)
SELECT @sequence = @sequence + 1
SELECT @tranLen = ABS(@tranLen - LEN(CAST(@sequence AS INT)))
SELECT @sequence = REPLICATE('0', @tranLen) + @sequence
END

DECLARE @DONORID AS [nvarchar](50) = 'DN' + CONVERT(VARCHAR, @sequence)

INSERT INTO [dbo].[DONORINFO] ([DONORID], [DONORNAME])
SELECT @DONORID, inserted.DONORNAME
FROM inserted


In the first lines of the script, I'm reading the
DONORINFO
table in which I checked if the unique id exists. After that, I will insert the record into that table. I tested the first time, the insert into select script works but for the second time around, it fails and sends and a violation of primary key error.

But if I tested row by row insert, it works.

This is the row by row insert script that works.

INSERT INTO [dbo].[DONORINFO] ([DONORID], [DONORNAME])
VALUES ('DN00000001', 'test')


If I run it twice, the records will be like this:

DONORID DONORNAME
---------------------
DN00000001 test
DN00000002 test


This is the insert into select script that doesn't work:

INSERT INTO [dbo].[DONORINFO] ([DONORID], [DONORNAME])
SELECT
'',
[NameOfDonor]
FROM
[dbo].[_TEMPENDOWMENTFUND] AS ENDF
WHERE
[ENDF].[NameOfDonor] NOT IN (SELECT [DONORNAME]
FROM [dbo].[DONORINFO])


The
_TEMPDOWMENTFUND
is a table I created that will store the data that was migrated from an Excel worksheet, the purpose of the trigger is that it will generate a unique
DONORID
for every record inserted on the
DONORINFO
table.

Now my problem is that, I want to perform the insert into select statement which is a multiple row insert, but I'm having a hard time figuring out what is going wrong to the trigger I created.

Any help would be appreciated. Thanks.

Answer

Make @sequence totally int (and probably rename it to last_id), add characters in the very end.

To number rows use ROW_NUMBER() in final select from INSERTED:

INSERT INTO [dbo].[DONORINFO] ([DONORID], [DONORNAME])
SELECT
  'DN' + REPLICATE('0', ABS(@len_you_need - LEN(t.generated_id))) + CAST (t.generated_id as varchar(100)),
  t.DONORNAME
FROM
(
SELECT
  i.DONORNAME, 
  @sequence+ROW_NUMBER()OVER(ORDER BY i.DONORNAME) as generated_id
FROM inserted i
) t

@len_you_need - is the length of DONORID you need. I guess this may be a constant of 8 characters. In your source you are calculating this here:

SELECT @tranLen = LEN(@sequence)

t.rn is a "sequence" value generated in subquery given above, which has t alias. Renamed it to generated_id for clarity.

This block:

BEGIN           
     SELECT @tranLen = LEN(@sequence)
     SELECT @sequence = @sequence + 1   
     SELECT @tranLen = ABS(@tranLen - LEN(CAST(@sequence AS INT)))
     SELECT @sequence =   REPLICATE('0', @tranLen) + @sequence
END 

is unnecessary anymore.