the trigger is using the base table, isntead of just the new rows that exist in the special virtual tables INSERTED AND DELETED

this will insert just the new rows:

CREATE TRIGGER [dbo].[trPopulateBulkPurchases]

ON [dbo].[tblTransactions]

AFTER INSERT

AS

BEGIN

INSERT INTO tblBulkPurchases

(tblBulkPurchases.PO_Number,

tblBulkPurchases.Buyer_Initial,

tblBulkPurchases.Quantity,

tblBulkPurchases.Transaction_Date,

tblBulkPurchases.Transaction_Type)

SELECT

INSERTED.PO_Number,

INSERTED.Buyer_Initial,

INSERTED.Quantity,

INSERTED.Transaction_Date,

INSERTED.Transaction_Type

FROM INSERTED

WHERE INSERTED.Transaction_Type = 'Bulk Purchase'

END

GO

edited: fixed table aliases: