select within select

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select within select

dr_csharp

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October 7, 2008 at 11:39 am

#198953

whats wrong with this 😕
SELECT A,B FROM (SELECT * FROM Table WHERE Id>5)
it has syntax error 🙁

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Garadin One Orange Chip Points: 29613 More actions · Answer 1

The word "Table" is a keyword. Try using something like MyTable instead.

Seth Phelabaum

Consistency is only a virtue if you're not a screwup. 😉

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TheRedneckDBA SSChampion Points: 14001 More actions · Answer 2

You might also need to give that inner query an Alias?

SELECT Tab.A,Tab.B FROM (SELECT * FROM Table) Tab

The Redneck DBA

dr_csharp SSCommitted Points: 1765 More actions · Answer 3

Jason Shadonix (10/7/2008)
You might also need to give that inner query an Alias?
SELECT Tab.A,Tab.B FROM (SELECT * FROM Table) Tab

thanks Jason you are right,but why we do this ?

i see most example of select within select in internet like select * from (select ..) without alias !?

Sergiy SSC Guru Points: 110208 More actions · Answer 4

Those examples must be not about SQL Server.

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RBarryYoung SSC Guru Points: 143329 More actions · Answer 5

dr_csharp (10/7/2008)
Jason Shadonix (10/7/2008)
You might also need to give that inner query an Alias?
SELECT Tab.A,Tab.B FROM (SELECT * FROM Table) Tab
thanks Jason you are right,but why we do this ?
i see most example of select within select in internet like select * from (select ..) without alias !?

SQL requires this because datasources need names so that you can refer to their columns and distinguish between columns of the same name from multiple datasources. Tables and Views already have names, but derived tables (like your subquery) do not, so you have to give it a name by using the alias syntax.

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Matt Miller (4) SSC Guru Points: 124210 More actions · Answer 6

dr_csharp (10/7/2008)
Jason Shadonix (10/7/2008)
You might also need to give that inner query an Alias?
SELECT Tab.A,Tab.B FROM (SELECT * FROM Table) Tab
thanks Jason you are right,but why we do this ?
i see most example of select within select in internet like select * from (select ..) without alias !?

The only "unnamed" subselects that are allowed within a SELECT don't live within the FROM clause. The two examples I can think of are the IN clause

...WHERE columnname IN (subquery) ....

or certain correlated sub-queries that appear in the SELECT portion of the statement.

SELECT myfield, (select count(*) from mytable2 b where a.id=b.id)

from MyTable a

The FROM clause however will require an alias.

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dr_csharp SSCommitted Points: 1765 More actions · Answer 7

Matt Miller (10/7/2008)
dr_csharp (10/7/2008)
Jason Shadonix (10/7/2008)
You might also need to give that inner query an Alias?
SELECT Tab.A,Tab.B FROM (SELECT * FROM Table) Tab
thanks Jason you are right,but why we do this ?
i see most example of select within select in internet like select * from (select ..) without alias !?
The only "unnamed" subselects that are allowed within a SELECT don't live within the FROM clause. The two examples I can think of are the IN clause
...WHERE columnname IN (subquery) ....
or certain correlated sub-queries that appear in the SELECT portion of the statement.
SELECT myfield, (select count(*) from mytable2 b where a.id=b.id)
from MyTable a
The FROM clause however will require an alias.

whats wrong with this :

Select * from Callrecorder where RecId between (select RecId from Table2 ) tempTable

ChrisM@Work SSC Guru Points: 186127 More actions · Answer 8

dr_csharp (10/8/2008)
whats wrong with this :
Select * from Callrecorder where RecId between (select RecId from Table2 ) tempTable

Firstly, as mentioned earlier, a table alias ('tempTable') is only required if the table is referenced in the FROM clause. Your subquery is referenced in the WHERE clause.

Secondly, BETWEEN requires two arguments. Without testing, something like this would work in theory:

SELECT * FROM Callrecorder

WHERE RecId BETWEEN (SELECT RecId FROM Table2 WHERE SomeWhereClause)

AND (SELECT RecId FROM Table2 WHERE SomeOtherWhereClause)

In practice, you'd assign the two RecId's to variables. You would, wouldn't you? 🙂

Cheers

ChrisM

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