if-not-exists is a common SQL condition used to check if an entity exists.

learn more… | top users | synonyms

8
votes
2answers
7k views

MySQL: Create index If not exists

Is there a way to create an index in MySQL if it does not exist? MySQL does not support the obvious format: CREATE INDEX IF NOT EXISTS index_name ON table(column) ERROR 1064 (42000): You have an ...
1
vote
1answer
59 views

MySQL: NOT EXISTS vs LEFT OUTER JOIN…IS NULL

Is NOT EXISTS or LEFT OUTER JOIN...IS NULL more efficient for finding records in one table that aren't in another? Specifically, I'm trying to figure out which of the two queries below is better: ...
1
vote
1answer
36 views

Increment value in row if it exists, otherwise create row with value?

Below is the MySQL table layout that I'm working with. Basically, I'd like to increment views, watchers, and inquiries as they occur through the front end of the website. My question is how would I ...
0
votes
1answer
119 views

MySQL : LEFT JOIN not fetching required data

I'm using left join in MySQL as mentioned below: SELECT Q.QUESTION_ID, school_id FROM Q_MASTER AS Q LEFT JOIN ( SELECT keyword, school_id FROM ...
2
votes
2answers
379 views

Check if row exists

I need to write a query that will insert a row only once, even if the query is run multiple times. Being new to SQL (well new-ish), I did an if not exists(...) but a friend said he preferred deleting ...
4
votes
3answers
1k views

Create procedure in else block on SQL Server

I have a SQL script in which I generate a database and its tables, stored procedures, views, etc. I have used following script to generate the database and all the things. I was able to generate ...
2
votes
1answer
9k views

MySQL: Execute CREATE TEMPORARY TABLE SELECT just one time?

I want to create a temporary table with some select-data. My (strange) problem is that I have to do the same query more than one time. CREATE TEMPORARY TABLE IF NOT EXISTS cache (id int(11) NOT ...
5
votes
2answers
1k views

What can I do to speed up this SQL Query?

I've created this SQL query with the help of @Dems :-) Here is some detail, I tried to make a SQLFiddle but I kept getting errors with my variables... This works in Sql Server 2008... My question ...