topic Re: joins in Application Development and Automation Discussions

joins

Former Member — Tue, 24 Apr 2007 05:02:12 GMT

Hi All,

can anyone please explain me the concept of joins in abap. i am new to abap and very confused with the concept of joins in oracle and abap. please explain by giving some small examples.

thanks and ragards

vivek

Re: joins

Former Member — Tue, 24 Apr 2007 05:03:23 GMT

hi,

check out the tcode ABAPDOCU

it contains many examples on joins.

regards,

Navneeth.K

Re: joins

Former Member — Tue, 24 Apr 2007 05:06:24 GMT

Hi,

Syntax

... [(] {dbtab_left [AS tabalias_left]} | join

{[INNER] JOIN}|{LEFT [OUTER] JOIN}

{dbtab_right [AS tabalias_right] ON join_cond} [)] ... .

Effect

The join syntax represents a recursively nestable join expression. A join expression consists of a left-hand and a right- hand side, which are joined either by means of [INNER] JOIN or LEFT [OUTER] JOIN . Depending on the type of join, a join expression can be either an inner ( INNER) or an outer (LEFT OUTER) join. Every join expression can be enclosed in round brackets. If a join expression is used, the SELECT command circumvents SAP buffering.

On the left-hand side, either a single database table, a view dbtab_left, or a join expression join can be specified. On the right-hand side, a single database table or a view dbtab_right as well as join conditions join_cond can be specified after ON. In this way, a maximum of 24 join expressions that join 25 database tables or views with each other can be specified after FROM.

AS can be used to specify an alternative table name tabalias for each of the specified database table names or for every view. A database table or a view can occur multiple times within a join expression and, in this case, have various alternative names.

The syntax of the join conditions join_cond is the same as that of the sql_cond conditions after the addition WHERE, with the following differences:

At least one comparison must be specified after ON.

Individual comparisons may be joined using AND only.

All comparisons must contain a column in the database table or the view dbtab_right on the right-hand side as an operand.

The following language elements may not be used: BETWEEN, LIKE, IN.

No sub-queries may be used.

For outer joins, only equality comparisons (=, EQ) are possible.

If an outer join occurs after FROM, the join condition of every join expression must contain at least one comparison between columns on the left-hand and the right-hand side.

In outer joins, all comparisons that contain columns as operands in the database table or the view dbtab_right on the right-hand side must be specified in the corresponding join condition. In the WHERE condition of the same SELECT command, these columns are not allowed as operands.

Resulting set for inner join

The inner join joins the columns of every selected line on the left- hand side with the columns of all lines on the right-hand side that jointly fulfil the join_cond condition. A line in the resulting set is created for every such line on the right-hand side. The content of the column on the left-hand side may be duplicated in this case. If none of the lines on the right-hand side fulfils the join_cond condition, no line is created in the resulting set.

Resulting set for outer join

The outer join basically creates the same resulting set as the inner join, with the difference that at least one line is created in the resulting set for every selected line on the left-hand side, even if no line on the right-hand side fulfils the join_cond condition. The columns on the right-hand side that do not fulfil the join_cond condition are filled with null values.

Example

Join the columns carrname, connid, fldate of the database tables scarr, spfli and sflight by means of two inner joins. A list is created of the flights from p_cityfr to p_cityto. Alternative names are used for every table.

PARAMETERS: p_cityfr TYPE spfli-cityfrom,

p_cityto TYPE spfli-cityto.

DATA: BEGIN OF wa,

fldate TYPE sflight-fldate,

carrname TYPE scarr-carrname,

connid TYPE spfli-connid,

END OF wa.

DATA itab LIKE SORTED TABLE OF wa

WITH UNIQUE KEY fldate carrname connid.

SELECT c_{carrname p}connid f~fldate

INTO CORRESPONDING FIELDS OF TABLE itab

FROM ( ( scarr AS c

INNER JOIN spfli AS p ON p_{carrid = c}carrid

AND p~cityfrom = p_cityfr

AND p~cityto = p_cityto )

INNER JOIN sflight AS f ON f_{carrid = p}carrid

AND f_{connid = p}connid ).

LOOP AT itab INTO wa.

WRITE: / wa-fldate, wa-carrname, wa-connid.

ENDLOOP.

Example

Join the columns carrid, carrname and connid of the database tables scarr and spfli using an outer join. The column connid is set to the null value for all flights that do not fly from p_cityfr. This null value is then converted to the appropriate initial value when it is transferred to the assigned data object. The LOOP returns all airlines that do not fly from p_cityfr.

PARAMETERS p_cityfr TYPE spfli-cityfrom.

DATA: BEGIN OF wa,

carrid TYPE scarr-carrid,

carrname TYPE scarr-carrname,

connid TYPE spfli-connid,

END OF wa,

itab LIKE SORTED TABLE OF wa

WITH NON-UNIQUE KEY carrid.

SELECT s_{carrid s}carrname p~connid

INTO CORRESPONDING FIELDS OF TABLE itab

FROM scarr AS s

LEFT OUTER JOIN spfli AS p ON s_{carrid = p}carrid

AND p~cityfrom = p_cityfr.

LOOP AT itab INTO wa.

IF wa-connid = '0000'.

WRITE: / wa-carrid, wa-carrname.

ENDIF.

ENDLOOP.

regards,

kiran kumar k

Re: joins

Former Member — Tue, 24 Apr 2007 05:09:21 GMT

hi,

we r using 2 type of joins in abap they are

1) inner join.

this will join 2 tables using an common fiend and return the result with field values wich are common in both the tables

itab1 itab2

a b c a d

1 2 3 1 5

2 3 4 3 6

after innerjoining itab1 n itab2 on field a we wil get the o/p as

a b c d

1 2 3 5

only common field is taken..

2)left outer join

here it wil work in opossite way it will give values whic are not common

itab1 itab2

a b c a d

1 2 3 1 5

2 3 4 3 6

after left outer joining itab1 n itab2 on field a we wil get the o/p as

a b c d

2 3 4

only fields which are not common is taken from the left table..other field(d here) wil be empty

reward if helpful

ravi

Re: joins

Former Member — Tue, 24 Apr 2007 05:14:41 GMT

hi Vivek,

The FROM clause determines the database tables from which the data specified in the SELECT clause is read. You can specify either a single table or more than one table, linked using inner or outer joins. The names of database tables may be specified statically or dynamically, and you can use alias names.

Inner Join Syntax.

Consider A and B are the tables and we are going to combine the Tables using Inner Join.

select a~name b~total b~branch a~reg_no into table it from zSample as a inner join zSample1 as b on a~reg_no = b~reg_no.

The Condition is At least One field is same between two Fields. Consider this example The Reg_no is The common field for both tables.

Example Program :

*tables: zvijirank,

zvijirank1.

ZVIJIRANK2.

*data : a type zvijirank occurs 10 with header line,

b type zvijirank1 occurs 10 with header line.

C TYPE ZVIJIRANK2 OCCURS 10 WITH HEADER LINE.

*data : name like zvijirank-name,

total like zvijirank1-total,
reg_no like zvijirank.

regno type i.

*data : begin of wa,

name type zvijirank-name,
total type zvijirank1-total,
branch type zvijirank1-branch,
reg_no type zvijirank-reg_no,

FNAME TYPE ZVIJIRANK2-F_NAME,
MNAME TYPE ZVIJIRANK2-M_NAME,
CITY TYPE ZVIJIRANK2-CITY,
TEL_NO TYPE ZVIJIRANK2-TEL_NO,

end of wa.

*data : it like standard table of wa with header line,

it1 like standard table of wa with header line.

*selection-screen : begin of screen 9010.

*parameters : regno type i matchcode object zreg.

*selection-screen : end of screen 9010.

**regno = '00100'.

*call selection-screen 9010.

*select a~name b~total b~branch a~reg_no into table it from zvijirank as a inner join zvijirank1 as b on a~reg_no = b~reg_no .

*loop at it.

*if it-reg_no eq regno.

*write : 'NAME :', it-name,

'REG_NO :', it-reg_no,
'TOTAL :', it-total.

*ENDIF.

*endloop.