Question

In my current job, I have to run SQL script once in a while to update my database. Mostly they are to update certain records that did not work properly.There is a page functionality to do the same but that is a bit longer route so I do it directly against the database.

I just ran an update query and accidentally updated all of my 30,000+ records. Luckily I was working in my test database.

    //Particular query that I am talking about is this
    update customers set  
    customer_id = 100 // where clause is missing and it will update all records

1. I was wondering, Is there a way to protect the database against such bulk update, may be a trigger that will half if update is affecting more than 500 records? Is there any way to protect database from accidental ill formatted queries. I am particularly interested in updates though.

2. Am I doing something really wrong when I use SQL Script directly against my production server. I am new and I need expert advice.

Answer 1

Looking at your query I assume that your Customers table doesn’t have a Primary Key with Identity turned on for the Customer_Id, having both these set on the table would certainly have stopped that script from completing.

I would suggest that you wrap your query in a transaction. Initially running the script with a rollback statement testing the output before you call Rollback. If the results are as you expected, replace the rollback with a commit and re-run the query.

EXAMPLE

BEGIN TRAN

UPDATE Customer SET Customer_ID = 100

SELECT * FROM Customer

ROLLBACK
--If results look OK comment out ROLLBACK and comment in the line below
--COMMIT