topic Re: select single vs distinct in Application Development and Automation Discussions

select single vs distinct

Former Member — Sat, 07 Apr 2007 02:22:31 GMT

hi,

what is the difference for select single and select distinct?

thanks

Re: select single vs distinct

Former Member — Sat, 07 Apr 2007 02:37:10 GMT

Hi,

This is the difference between these two

SELECT SINGLE

The result of the selection should be a single entry. If it is not possible to identify a unique entry, the system uses the first line of the selection. If you use the FOR UPDATE addition, the selected entry is protected against parallel updates from other transactions until the next database commit (see LUW and database lock mechanism). If the database system identifies a deadlock, a runtime error occurs.

SELECT DISTINCT

Duplicate entries in the result set are automatically deleted. There can be multiple entry exist in database for WHERE condition.

Let me know if you need any other information.

Regards,

Re: select single vs distinct

Former Member — Sat, 07 Apr 2007 02:52:18 GMT

select single statement is used to retrieve a single record by inputting all the combination of primary key as the search criteria. Here we retrieve a single unique record.

select distinct is used to retrieve a set of records satisfying the search criteria without any duplicate records. here you may not need to give the combination of primary key as search criteria.

Re: select single vs distinct

Former Member — Sat, 07 Apr 2007 03:51:23 GMT

Hi,

Please reward appropriate point and close the thread. It is a way to say thanks in forum.

Regards,