I am trying to insert rows into a table that has no unique field or primary key. How can I write a query that will simply ignore the insert if there already exists a row with the exact same values on all fields — a duplicate row?
Thanks.
Share
Sign Up to our social questions and Answers Engine to ask questions, answer people’s questions, and connect with other people.
Login to our social questions & Answers Engine to ask questions answer people’s questions & connect with other people.
Lost your password? Please enter your email address. You will receive a link and will create a new password via email.
Please briefly explain why you feel this question should be reported.
Please briefly explain why you feel this answer should be reported.
Please briefly explain why you feel this user should be reported.
I am trying to insert rows into a table that has no unique field or primary key. How can I write a query that will simply ignore the insert if there already exists a row with the exact same values on all fields — a duplicate row?
Thanks.
You must have a primary key or unique key defined on some column or columns in the table for uniqueness to have any meaning. Every mechanism for detecting duplicates automatically relies on this being true.
You can’t do the
SELECT COUNT(*)...solution because it’s subject to race conditions. That is, someone could insert a duplicate row in the moment after you select and before you insert. The only way around this is to lock the table withSELECT ... FOR UPDATEorLOCK TABLES.