Delete querry with where condition and substring takes long time

Question

0.00/5 (No votes)

See more:

hi i have delete query using substring

delete From [table] where SUBSTRING([field],1,CHARINDEX(N'',[field])-1) = 7

the query loops through millions of records,and takes long time,any sugesttion of tuning the query,(the table does not contain indexing or constrains)

Posted 6-Dec-12 2:36am

ramnath_k

Add a Solution

Comments

Rob Branaghan 6-Dec-12 8:45am

So you want to delete from the table where the field contains a 7?

BC @ CV 6-Dec-12 11:29am

Since SQL Substring() returns a varchar, nvarchar, text, ntext, varbinary or image why are you comparing it to the number 7? It would be easier to help you if you would state what you are trying to accomplish.

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Rohit Shrivastava · Answer 1 · 2012-12-06T09:47:00

Solution 1

You can create a persisted computed column based on the substring formula and compare that column as number 7. I would say if you are sure that it would be number cast the substring output to int, which will again make it faster.

Posted 6-Dec-12 9:47am

Rohit Shrivastava