IBM DB2

Precompilor-:

Precompilor's main purpose is to check the syntactical error of COBOL programes which contains embeded SQL statements.It first compiles & then differentiates cobol & DB2 statements.It sends all the DB2 queries to DBRM(database request module) and in that cobol program control makes those query lines as comment lines & issues CALL statement & that moves to MSC(modified sourse code).

Plan is generated when you compile the DB2-SQL program.

This plan is stored in the DBRM and binded to database as packages. (stored in syscat.syspackages - pkgname)

DBRM: Data base request module is generated by precompiler which contains the sql statements which are separated from the source program.

PACKAGE: By binding the DBRM package is generated.Package contains the internal structure of the original sql statements.

PLAN: It is the combination of packages that are bind to form a PLAN.

A VARCHAR column REMARKS would be defined as follows:

...

10 REMARKS.

49 REMARKS-LEN PIC S9(4) USAGE COMP.

49 REMARKS-TEXT PIC X(1920).

Never. New primary key values are not a problem. However, the values of foreign key inserts must have corresponding primary key values in their related tables. And updates of primary key values may require changes in foreign key values to maintain referential integrity

A31. The self-referencing constraint limits in a single table the changes to a primary key that the related foreign key defines. The foreign key in a self referencing table must specify the DELETE CASCADE rule.

No.

These are attributes of one table that have matching values in a primary key in another table, allowing for relationships between tables.

Keys (columns) that exist on one table and that are primary keys on another table.

100 ( for successful completion of the query ), 0 (for successful COMMIT if AUTOCOMMIT is set to Yes).

SELECT statement has resulted in retrieval of more than one row.

Authorization failure

Causes the data rows to be stored in the order specified in the index. A mandatory index defined on a partitioned table space.

Primary : a relational database constraint. Primary key consists of one or more columns that uniquely identify a row in the table. For a normalized relation, there is one designated primary key.

Unique index: a physical object that stores only unique values. There can be one or more unique indexes on a table