topic Re: joins in Application Development and Automation Discussions

joins

Former Member — Fri, 08 Dec 2006 08:58:45 GMT

1. what is the diff b/w inner join and outer join

2. what is index and use

Re: joins

Former Member — Fri, 08 Dec 2006 08:59:53 GMT

Check these to know the difference..

http://help.sap.com/saphelp_erp2005/helpdata/en/cf/21ec77446011d189700000e8322d00/frameset.htm

Re: joins

Former Member — Fri, 08 Dec 2006 09:01:54 GMT

Hi,

the difference lies in the data you are fetching from two tables..

its like sets..

unions means innerjoin

intersection means outer join.

Regards,

pankaj singh

Re: joins

Former Member — Fri, 08 Dec 2006 09:02:30 GMT

Hi,

1. The main difference between inner join and outer join is retrieveing no of records

INNER JOIN --> Retrieves all records condtion statisfied on left and right side tables.

OUTER JOIN ---> Retrieves all records from left side table whether conditon not satisfied also blank records will be joinned in right side table.

2. Indexes are used to improve performance of program. It reduces response time of SELECT Queries.

Regards

Bhupal Reddy

Re: joins

Former Member — Fri, 08 Dec 2006 09:03:20 GMT

HI Madhav ,

Inner join is basically used when the tables you are trying to joing have common values in the field you specify in the ON condition.

Outer join can be classified as Left Outer join and Right outer join, if it is a left outer join then the values in the table mentioned in the left (before the command LLEFT OUTER JOIN ) will be selected irrespective of whether there is value in the table in right or not for the said condition.

Index are a concept similar to creating another set of primary key for the table , they are created on non primary keys and help in reducing the access time when you search the table with that filed on which the index is created.

Regards

Arun

Re: joins

Former Member — Fri, 08 Dec 2006 09:50:46 GMT

hi,

INNER JOIN : this will retrieve all values from both the tables you specify in your

select(i.e, the table on the left and right).

OUTER JOIN : this is classified into left outer join and right outer join.

1. left : this retrieves all the values from the left table alone.

2. right : this retrieves all the values from the table on the right alone.

Re: joins

Former Member — Fri, 08 Dec 2006 15:08:28 GMT

inner join : With inner join you get records only when there is entry in all tables.

outer join : With outer join records are also selected when there is no entry in some of the tables.

Re: joins

Former Member — Mon, 11 Dec 2006 05:23:56 GMT

hi madhav,

1. Innerjoin is one which retrives data from both left and right side of tables based on condition.

outer join retrives data from either left or right side of the table based on condition..

two types of outer join are LEFT and RiGHT outer join..

but in abap we have only LEFT OUTER JOIN..

2. Index denotes the row count and it can be use d in select statements to retrive data if we know the line where the data is stored..

it is like select * from table into it where index = 1.

hope i have answered u..

regards,

Rajkumar.G

Re: joins

Former Member — Mon, 11 Dec 2006 06:12:33 GMT

1. what is the diff b/w inner join and outer join

The data that can be selected with a view depends primarily on whether the view implements an inner join or an outer join.

With an inner join, you only get the records of the cross-product for which there is an entry in all tables used in the view.

With an outer join, records are also selected for which there is no entry in some of the tables used in the view.

Database views implement an inner join. The database therefore only provides those records for which there is an entry in all the tables used in the view. Help views and maintenance views, however, implement an outer join.

Have a look at these links:

2. what is index and use

You can speed up a table search for data records that satisfy certain search criteria by using an index. You can create more than one index for a table.

In addition to the primary key, which you define in the ABAP Dictionary when creating a table, you can also define additional indices (called database indices) for transparent tables. Using indices, you can improve the time needed to access and read your database table.

An unique index ensures that no duplicates are entered in a table.

Have a look at this link:

<a href="http://help.sap.com/saphelp_nw04/helpdata/en/c7/55833c4f3e092de10000000a114027/frameset.htm">http://help.sap.com/saphelp_nw04/helpdata/en/c7/55833c4f3e092de10000000a114027/frameset.htm</a>

Regards,

Gunasree.

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Re: joins

Former Member — Mon, 11 Dec 2006 06:29:01 GMT

HI ,

table A table B

sno. name telno sno . add

1 xxxx 2222 1 www

2 yyyy 3333 3 uuu

3 zzzz 4444 4 ooo

inner join .

sno. name telno add

1 xxxx 2222 www

3 zzzz 4444 uuu

outer join .

sno. name telno add

1 xxxx 2222 www

2 yyyy 3333 ---

3 zzzz 4444 uuu

4 -

ooo

Message was edited by:

Lakshminarayanan rohini