Table alias in Sub queries

[VE]

Other than readability and personal preference, are their any rules to aliasing tables in sub queries?

For instance, if you alias a table in the outer query AB, is there any scenario where giving a table in a sub query the alias AB would cause problems?

Or if a table used in the outer table is also used in a sub query should you give it a different alias in the sub query?

If it maters where can I find a list of rules? I don't seem to be using the right words when I search.

If it doesn't mater, what to you think it the most readable way to alias tables in sub queries?

Thank you
VE

 

[fredericofonseca]

search for sql server coding standards -- you will find many - take the good things out of them and ignore the rest - one example with good things is

http://sqlstandards.codeplex.com/

In my opinion unique alias throughout as you never know if you are going to need to change a sub-query to a correlated query

Regards

Frederico Fonseca
SysSoft Integrated Ltd

http://www.syssoft-int.com

FAQ219-2884
FAQ181-2886

 

[gk53]

Use alias always if you join tables it make code clear

 

[djj55]

As gk53 indicated the alias help keep things clear. So it may not cause a SQL error to have the same alias within a subquery and query but it can get confussing. I do not have an example of where a problem might occur but ...

djj
The Lord is my shepherd (Psalm 23) - I need someone to lead me!