database access 01 (1)

8/13/2019 Database Access 01 (1)

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Accessing Database tables

In a SAP system, data from a database can be accessed by

an ABAP program by using the following type of statements:Open SQLIt is a subset of standard SQL, consists of a

set of ABAP statements that perform operations on the

database tables. It provides a uniform syntax and semantics

for all the database systems supported by SAP. Open SQL

statements can work with database tables that have been

created in the ABAP dictionary.

Native SQL- It contains only database manipulation

statements. Database tables that are not administered by the

ABAP dictionary can be accessed by the Native SQL. Anative SQL statement is used within the EXEC SQL and

ENDEXEC statements.


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Steps to create Database Tables:

Go to ABAP Dictionary.

Choose the Database table and type in the table name spfli.

Then use the Display button to have a look at the table

definition. The following tabs are available.

Attributes- The attribute tab show you to which package the

table is assigned and who did the last changes.

Delivery and maintenanceThis is a very important tab as it

show you to which delivery class the table is assigned and if

changes to the table are allowed or not.


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I. Display/Maintenance Allowed with Restrictions

II. Display/Maintenance Allowed

III. Display/Maintenance Not Allowed


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Fields - name of field, key, data element, data type, length,

short description etc.

Entry help/checkThis tab shows you if any check tables

are used and if there is a search help available.

Currency/quantity fieldsThe last tab is important when the

table contains currency data as it is necessary to choose a

reference currency from a customizing table then.


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Commonly Used Open SQL Statements

Select Reads data from databasetables

Insert Add lines to tables

Update Changes the contents of a

line

Delete Delete lines of table

Open cursor, fetch, close

cursor

Read lines of database

tables using the cursor


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Database Access

Read database data into internal tables. Internal tables are

tables for holding data during runtime.

Change data per rowuse work areas to hold one row of

the table and change data in the work area.

Write changes back to database.


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Inserting data into table-

The Open SQL statement for inserting data into a

database table is:

INSERT INTO .

It allows you to insert one or more lines into the

database table .

You can specify the database table either

statically or dynamically.


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Specifying a Database Table

To specify the database table statically, enter the

following for :INSERT INTO .

where is the name of a database table

defined in the ABAP Dictionary.

To specify the database table dynamically, enter thefollowing for :

INSERT INTO () .

where the field contains the name of adatabase table defined in the ABAP Dictionary.


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Inserting a Single Line

To insert a single line into a database table, use thefollowing:

INSERT INTO VALUES .

You can also insert single lines using the followingshortened form of the INSERT statement:

INSERT FROM .

Using FROM instead of VALUE allows you to omit the INTO

clause.


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tables spfli.

data wa type spfli.

wa-carrid = 'lh'.wa-cityfrom = 'washington'.

...

insert into spfli values wa.

wa-carrid = 'ua'.

wa-cityfrom = 'london'.

...insert spfli from wa.


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spfli-carrid = 'lh'.

spfli-cityfrom = 'berlin'.

...insert spfli.

This program inserts a single line into the database

table SPFLI using each of the three possible variants of

the INSERT statement.


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Updating database rows

The Open SQL statement for changing data in a

database table is:

UPDATE .

It allows you to change one or more lines in the database

table . You can only change lines in an ABAP

Dictionary view if it only contains fields from one table,and its maintenance status is defined as Read and

change. You may specify the database table

either statically or dynamically.


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Specifying a Database Table

To specify the database table statically, enter the

following for :UPDATE .

where is the name of a database table defined

in the ABAP Dictionary.

To specify the database table dynamically, enter the

following for :

UPDATE () .where the field contains the name of a

database table defined in the ABAP Dictionary.


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Changing Lines Column by Column

To change certain columns in the database table, use the

following:

UPDATE SET ... [WHERE ].

The WHERE clause determines the lines that are changed. If you

do not specify a WHERE clause, all lines are changed.


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The expressions are three different SET

statements that determine the columns to be

changed, and how they are to be changed: =

The value in column is set to the value for

all lines selected.

= +

The value in column is increased by the value

of for all lines selected.

= -

The value in column is decreased by the value

of for all lines selected.


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can be a data object or a column of the database

table. You can use the attributes of the table using their

direct names.

If at least one line is changed, the system sets SY-

SUBRC to 0, otherwise to 4. SY-DBCNT contains thenumber of lines changed.

If you use SET statements, you cannot specify the

database table dynamically.


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Overwriting Individual Lines From a Work Area

To overwrite a single line in a database table with the

contents of a work area, use the following:

UPDATE FROM .

The contents of the work area overwrite the line in

the database table that has the same primary key.

If the database table contains a line with the same primary

key as specified in the work area, the operation is completed

successfully and SY-SUBRC is set to 0. Otherwise, the line is

not updated, and SY-SUBRC is set to 4.


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A shortened form of the above statement is:

UPDATE .

In this case, the contents of the table work area are used to update the database table with

the same name. You must declare this table work

area using the TABLES statement. In this case, it is

not possible to specify the name of the databasetable dynamically.


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Overwriting Several Lines Using an Internal Table

To overwrite several lines in a database table with the

contents of an internal table, use the following:UPDATE FROM TABLE .

The contents of the internal table overwrite the

lines in the database table that have the sameprimary keys. The same rules apply to the line type of

as to the work area described above.


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If the system cannot change a line because no line with

the specified key exists, it does not terminate the

operation, but continues processing the next line of the

internal table.If all lines from the internal table have been processed,

SY-SUBRC is set to 0. Otherwise, it is set to 4. If not all

lines are used, you can calculate the number of unused

lines by subtracting the number of processed lines in SY-DBCNT from the total number of lines in the internal table.

If the internal table is empty, SY-SUBRC and SY-DBCNT

are set to 0.

Whenever you want to overwrite more than one line in adatabase table, it is more efficient to work with an internal

table than to change the lines one by one.


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Example -

UPDATE SFLIGHT SET PLANETYPE = 'A310'

PRICE = PRICE - '100.00'WHERE CARRID = 'LH' AND CONNID = '0402'.

This example overwrites the contents of the

PLANETYPE column with A310 and decreases the

value of the PRICE column by 100 for the entry inSFLIGHT where CARRID contains LH and

CONNID contains 402.


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TABLES SPFLI.

DATA WA TYPE SPFLI.

MOVE 'AA' TO WA-CARRID.MOVE '0064' TO WA-CONNID.

MOVE 'WASHINGTON' TO WA-CITYFROM.

...

UPDATE SPFLI FROM WA.

MOVE 'LH' TO SPFLI-CARRID.

MOVE '0017' TO SPFLI-CONNID.

MOVE 'BERLIN' TO SPFLI-CITYFROM.

...

UPDATE SPFLI.


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In this example, CARRID and CONNID are the primary key

fields of table SPFLI. All fields of those lines where the primary

key fields are "AA" and "0064", or "LH" and "0017", are

replaced by the values in the corresponding fields of the workarea WA or the table work area SPFLI.


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Reading Data from database table-

The Open SQL statement for reading data from database

tables is:

SELECT

INTO

FROM

[WHERE ]

[GROUP BY ][HAVING ]

[ORDER BY ].


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REPORT ZY_PRGM1.

tables zzemp320.

data: itab type table of zzemp320, wa type zzemp320.wa-empid = 11.

wa-name = 'ss'.

insert into zzemp320 values wa.

write sy-subrc.

select * from zzemp320 into table itab.

loop at itab into wa.

write: / wa-empid,wa-name.endloop.


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REPORT ZY_100_FLIGHTS.

data it_flights type table of spfli.

data wa_flights type spfli.select * from spfli into table it_flights.

loop at it_flights into wa_flights.

write: / wa_flights-connid,wa_flights-cityfrom,

wa_flights-cityto.

endloop.


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REPORT ZY_100_FLIGHTS.

data it_flights type table of spfli.

data wa_flights type spfli.select * from spfli into table it_flights.

if sy-subrc = 0.

loop at it_flights into wa_flights.

write: / wa_flights-connid,wa_flights-cityfrom,wa_flights-

cityto.

endloop.

else.

write: 'sql statement was not successfully'.

endif.


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Return Codes

All Open SQL statements fill the following two system fields with return

codes:

SY-SUBRC :- After every Open SQL statement, the system field SY-

SUBRC contains the value 0 if the operation was successful, a value

other than 0 if not.

SY-DBCNT :- After an open SQL statement, the system field

SY-DBCNT contains the number of database lines processed.


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Data Types in ABAP Dictionary

You can assign a predefined ABAP Dictionary type and a

number of characters to an elementary type. The ABAPDictionary has considerably more predefined types than the

ABAP programming language. The number of characters here

is not the field length in bytes, but the number of valid

characters excluding formatting characters. The data types are

different because the predefined data types in the ABAP

Dictionary have to be compatible with the external data types

of the database tables supported by the SAP Web AS ABAP.


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Dictionary type Meaning Maximum length n ABAP type

DEC Calculation/amount

field

1-31, 1-17 in tables P((n+1)/2)

INT1 Single-byte integer 3 Internal only

INT2 Two-byte integer 5 Internal only

INT4 Four-byte integer 10 I

CURR Currency field 1-17 P((n+1)/2)

CUKY Currency key 5 C(5)

QUAN Quantity 1-17 P((n+1)/2)


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DATS Date 8 D

ACCP Accounting period

YYYYMM

6 N(6)

TIMS Time HHMMSS 6 T

RAW Byte sequence 1-255 X(n)

LRAW Long byte sequence 256-max X(n)

CLNT Client 3 C(3)

LANG Language internal 1, external 2 C(1)

DATS Date 8 D

database access 01 (1)

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