Select * v/s select specific in oracle

Dear Friends please proivde your valuable opinions:
how does oracle behaves internally in case when all records are selected (select * from X) and in case when few records ( select A, B from X) selected.
I had a discussion with my DBA DBA says even if you select specific column oracle internally selects the whole row (all columns) and then selects specific columns out of it.
Being an application developer I believe that specific column selection is fast and oracle should not be selecting all columns internally.
Arpit Bansal

Aside from the fact that selecting a particular column list is a heck of a lot safer, since it doesn't break when new columns are added to a table, selecting a subset of the columns may be more efficient, particularly if it reduces the amount of data that needs to be sorted or hashed or if it allows all the data to be fetched from an index. If Oracle has to read data from the table itself, it will generally have to read the entire row into the buffer cache (overflow segments in an IOT being the biggest exception I can think of).
Justin
Added clarification about queries that can be satisfied exclusively via indexes.
Message was edited by:
Justin Cave

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A very slow select with sub selects sql statement on Oracle

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5       , count(decode(job,'SALESMAN',1)) salesman
6    from dept, emp
7   where dept.deptno = emp.deptno (+)
8   group by dept.deptno
9       , dept.dname
10 /
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        40 OPERATIONS              0          0          0
4 rijen zijn geselecteerd.will be worth the effort.
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Selecting the first n rows with Oracle

Please help,I am very confused with this.
For example,lets take a table called "items" which has
ID    NAME    PRICE
1    cup              1.2
2    book         49.99
3    mobile        89.99
20    bike        1250
19    egg            0.8
18    bun           2.5
17    color          2.22
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15    air            0
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13    pack         21.53
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NAME                      PRICE
coke                        .78
cup                         1.2
pencil                     1.35
book                      49.99
mobile                    89.99
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Oracle first retrieves the first five rows and then orders them by price. This is because of the fact that we didn't explicitly enough state what we meant with first.
This problem can be solved by using row_number with a option--->below
select name, price
from (
_*select name, price, row_number() over (order by price) r*_
_*from items*_
where r between 1 and 5;
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air                           0
coke                        .78
egg                          .8
dollar                        1
apple                      1.05
**Question is in the above select if i ADD the clause "WHERE rownum <= 6"---The above result set goes wrong again.I dont get the correct order as above.
Please help.Can we have the order by done first and then take 5 records of them.
select name, price
from (
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where r between 1 and 5

wrote:user_7000011
Thanks.
*But, what i wanted is in the inner most select where we select from item --I need to add a where qualification as below.*
select * from
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) a
where a.rank<6
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In order to order first and then take 6 rows you have to order your data without restriction and then wrap that in a query to restrict it.
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select x
from tableX
where rownum <= 6
order by xbecomes
select x
from (select x
      from   tableX
      order by x)
where rownum <= 6This ensures that the data is selected and ordered first and then the first 6 rows are taken from that.

Bug report select statement nested select in FROM Clause on Oracle 10g

The SELECT statement below does not return the appropriate result; it used to work on Oracle 8, but it does not on 10g (10.2).
Here is the table
create table T (
A numeric(4),
B numeric(4)
Some data
insert into T (A,B) VALUES (1,null);
insert into T (A,B) VALUES (2,1);
insert into T (A,B) VALUES (3,1);
insert into T (A,B) VALUES (3,2);
The select statement returning the worng result
select totals.A, totals.totalBbyA
from (
select t1.A, sum(t1.B) totalBbyA
from T t1
group by A
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where
totals.totalBbyA >= all
select sum(nvl(t2.b,0)) from T t2 group by t2.a
it returns "no rows selected"
An equivalent select that does return the good result
select t1.A, sum(t1.B) totalBbyA
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group by A
having
sum(t1.B) >= all
select sum(nvl(t2.b,0)) from T t2 group by t2.a
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A TOTALBBYA
3 3
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910893 wrote:
but it does not on 10g (10.2).Works fine in:
SQL> select *
2    from v$version
3 /
BANNER
Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - Prod
PL/SQL Release 10.2.0.4.0 - Production
CORE    10.2.0.4.0      Production
TNS for 32-bit Windows: Version 10.2.0.4.0 - Production
NLSRTL Version 10.2.0.4.0 - Production
SQL> select *
2    from t
3 /
         A          B
         1
         2          1
         3          1
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2 from (
3 select t1.A, sum(t1.B) totalBbyA
4 from T t1
5 group by A
6 ) totals
7 where
8 totals.totalBbyA >= all
9 (
10 select sum(nvl(t2.b,0)) from T t2 group by t2.a
11 )
12 ;
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"select count(*)" and "select single *" returns different result

Good day!
product version SAP ECC 6.0
oracle10
data transfers from external oracle db into customer tables using direct oracle db link
sometimes I get case with different results from 2 statements
*mytable has 10 rows
*1st statement
data: cnt type I value 0.
select count( * ) into cnt from mytable WHERE myfield_0 = 123 and myfield_1 = '123'.
*cnt returns 10 - correct
*2nd statement
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but
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Thank you, Vishal
but,
general problem is that
1. both statements have the same WHERE conditions
2. 1st return resultset with data (sy-dbcnt=10), 2nd return empty dataset, but must return 1 in sy-dbcnt
Yes, different meaning, you are right, but must 2nd must return 1, because of "select single *" construction, not 0.
Dataset to process is the same, WHERE conditions are equal...
I think the problem is that how ABAP interperets select count(*) and "select single *".
Maybe "select count (*)" scans only PK from index page(s)? and "select single *" scans data pages? and something is wrong with that?
I'm new in SAP and didn't find any SAP tool to trace dump of data and indexes pages with Native SQL.
se16 shows all records.
And why after simple manual update of just one record using se16 "select single *" returns 1?
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Hi
We have a report set-up and which we want to run using our adhoc query report tcode S_PH0_48000513
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Error during selection; check the selection conditions
Message no. PAIS206
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Diagnosis
A runtime error occurred during dynamic selection.
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orton

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    private String masterField3;
     private String masterField4;
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    private String detailField1;
    private String detailField2;
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     private String detailField4;
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    private String detailFieldn;
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@NamedQueries({
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public class MasterHelper implements java.io.Serializable {
    private String field1;
    private String field2;
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     //getters and setters
public class DetailHelper implements java.io.Serializable {
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}So, basically when i query for a particular Master entity, what i want in return is a List of MasterHelper objects with just the fields i want; each MasterHelper object must include a list of MasterDetail objects, again with just the fields i want.
When the above named query is executed by Toplink Essentials against an Oracle database, i get the following exception regarding the "second" SELECT NEW:
EJBQLException
Exception Description: Syntax error parsing the query [SELECT NEW
...unexpected token [SELECT]
...How can i achieve what i want? Doesn't JPA allows SELECT NEW inside SELECT NEW in named queries?
Thanks in advance for any help.
Edited by: savas_karabuz on May 16, 2008 3:59 AM
Edited by: savas_karabuz on May 16, 2008 4:02 AM

Hello,
The build you are using is an older one, and there have been a few enhancements done for constructor expressions support (for instance
https://glassfish.dev.java.net/issues/show_bug.cgi?id=1421)
but an enhancement to allow constant values is still open: https://glassfish.dev.java.net/issues/show_bug.cgi?id=2452
Best Regards,
Chris

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what is the difference b/w
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Hi,
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The salesperson for my iphone 4 said on Christmas morning we could go to our online account, select my number, select to change my SIM card, and enter the ICCID number so that I'd be able to use my iphone 4 today. I have not seen any such steps. Help?

The salesperson for my iphone 4 said on Christmas morning we could go to our online account, select my number, select to change my SIM card, and enter the ICCID number so that I'd be able to use my iphone 4 today instead of my old phone (not an iphone). I have not seen any such steps. Help?

I suspect the salesperson that told you that meant your online account with your carrier...have you tried logging into your carrier account online? To do this will require the sim number on your sim card, as well as the phone's IMEI number...you get the sim number off the sim card & the IMEI number, for the phone, is printed on the box.

Select * v/s select specific in oracle

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