@wio

Question

@wio

dls · Answer

I am gonna ask you many questions sorry :D
What does "Create view" command do?

dls · Answer

(in general) basically

anonymous · Answer

Create view

In mysql?

dls · Answer

yes

anonymous · Answer

I dunno.  I just read the docs, and it looks like it lets you create a table from a query which you can query against.

dls · Answer

table from a query? o.O whats the use?

anonymous · Answer

I have never needed to use it myself.

dls · Answer

Can u tel smt about Joint and union??

anonymous · Answer

What about it?

dls · Answer

what they do..how they work..etc..anything :/ just the basic idea

anonymous · Answer

Union just combines two select statements into a single result.

dls · Answer

and joint?

anonymous · Answer

I see join, but not joint.

dls · Answer

sorry its joins only ^^

dls · Answer

What does this line mean?
The ORDER BY clause can occur only at the end of the UNION statement.It CANT be used within the individual queries that make the UNION statement.
The GROUP BY and HAVING clauses are allowed only within individual queries.These clauses cannot be used to affect the final result set.

anonymous · Answer

Suppose you have two queries,  Q1 and Q2

anonymous · Answer

You can't put an ORDER BY on Q1 or Q1 if you 're going to union them.

anonymous · Answer

However, suppose we call the union Q3

anonymous · Answer

Q3 can have an order by.

anonymous · Answer

However Q3 can't have group by or having.  Yet  Q1 and Q2 can use group by and having

dls · Answer

can u explain in a bit more detail? hard to visualize lol..

e.mccormick · Answer

Some uses for views: http://stackoverflow.com/questions/1278521/why-do-you-create-a-view-in-a-database

dls · Answer

answer other questions too!

dls · Answer

@e.mccormick

e.mccormick · Answer

These seem quite literal to me.

"The ORDER BY clause can occur only at the end of the UNION statement.  It CANT be used within the individual queries that make the UNION statement."

"The GROUP BY and HAVING clauses are allowed only within individual queries.  These clauses cannot be used to affect the final result set."

They say when things can and can not be done.  WHY they can and can not be done at those points has to do with the development of SQL.  I do not know enough about that to explain the why.  But the what is a set of rules similar to order of operations in math.  Thing have to happen in the proper order or they will not work.