Database Access using Advanced Business Application Programming (ABAP)
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by Arindam Ghosh
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Native SQL

The other possible way to access the database from a program is Native SQL. It is only loosely integrated into ABAP. It allows access to all of the functions contained in the programming interface of the respective database system. Native SQL statements are not checked and converted as compared to Open SQL statements. Unlike Open SQL, these are sent directly to the database system. The function of the database-dependent layer remains minimal when you use Native SQL. The Programs which use Native SQL are written specifically for a database system. You should avoid using Native SQL wherever possible when writing R/3 applications. However, you can use it in some parts of the R/3 Basis System, for instance, for creating or changing table definitions in the ABAP Dictionary.

Regardless of the database platform that your R/3 system is using, Open SQL allows you to access database tables, which are declared in the ABAP Dictionary. Native SQL allows you to use database specific SQL statements in an ABAP program. This means that you can use database tables that are not administered by the ABAP Dictionary. Aside from that, you can also integrate data that is not part of the R/3 system.

As a rule, an ABAP program that contains database-specific SQL statements will not run under different database systems. You have to use Open SQL statements only, if your program is used on more than one database platform.

You must proceed with the EXEC SQL statement, and follow the ENDEXEC statement to use a: Native SQL statement. For example

Listing 1

EXEC SQL [PERFORMING <form>].
      <native SQL, statement>
ENDEXEC.

There is no period after Native SQL statements. Also, using quotation marks (") or an asterisk (*) at the beginning of a native SQL statement's line does not introduce a comment as it would in normal ABAP syntax. You need to know if the table and field names are case-sensitive in your chosen database.

The data is transported between the database table and the ABAP program using host variables in Native SQL statements. These are preceded in a Native SQL statement by a colon (:) and are declared in the ABAP program. The elementary structures can be used as host variables. The structures of an INTO clause are treated exceptionally, as though all of their fields are listed individually. If the selection in a Native SQL SELECT statement is a table, then you can pass it to ABAP line by line using the PERFORMING addition. For each line read, the program calls a subroutine <form>. Further, you can process the data within the subroutine.

After the ENDEXEC statement, SY-DBCNT contains the number of lines processed as it does in Open SQL. In almost all cases, SY-SUBRC contains the value a after the ENDEXEC statement. Cursor operations form an exception: after FETCH, SY-SUBRC is 4 if no more records could be read. This is also applied when you read a result set using EXEC SQL PERFORMING.


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