The MERGECOPY is just opposite of IMAGECOPY. This DB2 utlility is used to combine the multiple image copy datasets into a new full or incremental image copy. This is mainly used to restore the backup in the DB2 table.The below JCL step can be used for the incremental MERGECOPY for DB2 table TAB1 which is residing in the database DBSET1−//STEP010 EXEC DSNUPROC //COPY1 DD DSN=TEST.DB2.COPY1, DISP=(MOD, CATLG, CATLG), // UNIT=SYSDA, SPACE=(4000, (20, 20), , , ROUND) //COPY2 DD DSN=TEST.DB2.COPY2, DISP=(MOD, CATLG, CATLG), // UNIT=SYSDA, SPACE=(4000, (20, 20), , , ROUND) //SYSOUT DD SYSOUT=* //SYSIN DD * MERGECOPY TABLESPACE DBSET1.TBSPAC01 COPYDDN ... Read More

The declared temporary tables are also non-permanent tables but unlike created temporary tables they can be defined in the application program. The existence of a declared temporary table is limited to program execution. Since the declared temporary tables are created and deleted at the runtime, their entries are not stored into DB2 system table SYSIBM.SYSTABLES.The declared temporary table can be defined in the program using DECLARE GLOBAL TEMPORARY TABLE statement. The advantage of a declared temporary table over a created temporary table is that we can add constraints and indexes in these tables.

The Created temporary tables are non-permanent DB2 tables that exist as long as the process using this table is active. For example any batch program. The created temporary tables are best suited for the sequential access and hence system performance is not a concern over here.The created temporary tables can be created using the DDL statement CREATE GLOBAL TEMPORARY TABLE followed by the name of the temporary table. This statement makes the entry of the new table in DB2 system table SYSIBM.SYSTABLES with type column as ‘G’.The created temporary table should always be created using the above DDL statement before ... Read More

To get a DB2 view definition we can use the SYSIBM.SYSVIEW DB2 system table. The SYSVIEW table stores the details about all the views that exist in DB2. We can give below SQL statement to find the view definition.SELECT NAME, SEQNO, TEXT    FROM SYSIBM.SYSVIEWS WHERE NAME = ‘VIEW1’       ORDER BY SEQNO;The VIEW can have definitions in multiple lines denoted by the SEQNO. That is the reason we need to use ORDER BY SEQNO so as to give the view definition in correct order. The exact definition is available in the TEXT column.

SYSIBM.SYSTABAUTH is a DB2 system table which records the privileges that users/program hold on tables and views. We can use this table to find out the list of programs accessing a particular table and what action the program is performing on the table like SELECT, UPDATE, INSERT or DELETE. The below SQL query can be fired on SYSTABAUTH in order to get list of programs.SELECT GRANTEE, SELECTAUTH, UPDATEAUTH, INSERTAUTH, DELETEAUTH FROM SYSIBM.SYSABAUTH WHERE GRANTEETYPE = ‘P’ AND TNAME = ‘TAB1’The column SELECTAUTH, UPDATEAUTH, INSERTAUTH and DELETEAUTH represents SELECT, UPDATE, INSERT and DELETE authority respectively. In the WHERE clause we will ... Read More

To find out all the indexes built on the DB2 table TAB1 we can use the DB2 system table SYSIBM.SYSINDEXES. The SYSINDEXES database has one row for every index present in DB2. We can find indexes built on a particular table using the below SQL query.SELECT NAME, UNIQUERULE, CLUSTERING    FROM SYSIBM.SYSINDEXES WHERE TBNAME=’TAB1’The column UNIQUERULE in the SELECT statement returns ‘P’ for primary index and ‘U’ for alternate index. The CLUSTERING column will be returned as ‘YES’ for clustered index and ‘NO’ for non-clustered index.

The foreign key of a DB2 table can be found using SYSIBM.SYSFOREIGNKEYS table and SYSIBM.SYSRELS table. The SYSFOREIGNKEYS is a DB2 system table which contains one row for every column of every foreign key. The SYSRELS table contains details about the referential constraints. In order to find out the foreign key(s) of any table, we can use the below SQL query.SELECT B.REFTBNAME AS PARENTTABLE, COLNAME FROM SYSIBM.SYSFOREIGNKEYS A, SYSIBM.SYSRELS B WHERE A.RELNAME = B.RELNAME AND B.TBNAME = 'TAB1' AND B.REFTBCREATOR = A.CREATORWe will join SYSFOREIGNKEYS and SYSRELS table for the columns RELNAME which stores the details regarding constraint name for ... Read More

We can find the primary key of any table using the SYSIBM.SYSCOLUMNS table. The SYSIBM.SYSCOLUMNS is a DB2 system table which contains one row for every column of each table. It also contains the data related to the views. Below SQL query can be fired in order to find the primary key of a particular table.SELECT NAME FROM SYSIBM.SYSCOLUMNS WHERE TBNAME = 'TAB1’ AND KEYSEQ > 0 ORDER BY KEYSEQ ASC;We will use our table name in the TBNAME column of SYSCOLUMNS table using the WHERE clause and KEYSEQ > 0 will return only primary keys.

The ALIAS is basically a different name given to a particular object in a database. An ALIAS can be defined for a table, view or another alias and the existence of the object is not verified during the creation of the alias. The ALIAS is used to hide the location qualifier and we need SYSADM authority to create a new ALIAS. When the object is dropped, its corresponding ALIAS is not dropped.We can use the below command in order to create a new ALIAS for a table.CREATE ALIAS T1    FOR DBSET1.TAB1The CREATE ALIAS reserved words are followed by the ... Read More

The image copy allows us to download or copy the DB2 table into a mainframe dataset. There are two types of Image copy i.e. Full image copy and Incremental image copy. The full image copy is used to take the backup of the entire table. The incremental image copy refers to the differential backup. In order to take the full image copy of the DB2 table we can use the below JCL step.//STEP1 EXEC DSNUPROC //SYSCOPY DD DSN=TEST.TAB1.COPY, UNIT=SYSDA, VOL=SER=CPY01I, // SPACE=(CYL, (15, 1)), DISP=(NEW, CATLG, CATLG) //SYSOUT DD SYSOUT=* //SYSIN DD * COPY TABLESPACE TAB1SPAC /*We can use the ... Read More