Application Programming and SQL Guide - Kmlinux

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Example: Suppose that you create a definition of TEMPPROD and then run an
application that contains the following statements:
EXEC SQL DECLARE C1 CURSOR FOR SELECT * FROM TEMPPROD;
EXEC SQL INSERT INTO TEMPPROD SELECT * FROM PROD;
EXEC
.
SQL OPEN C1;
.
EXEC
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SQL COMMIT;
.
EXEC SQL CLOSE C1;
When you run the INSERT statement, DB2 creates an instance of TEMPPROD and
populates that instance with rows from table PROD. When the COMMIT statement
is run, DB2 deletes all rows from TEMPPROD. However, assume that you change
the declaration of cursor C1 to the following declaration:
EXEC SQL DECLARE C1 CURSOR WITH HOLD
FOR SELECT * FROM TEMPPROD;
In this case, DB2 does not delete the contents of TEMPPROD until the application
ends because C1, a cursor defined WITH HOLD, is open when the COMMIT
statement is run. In either case, DB2 drops the instance of TEMPPROD when the
application ends.
Working with declared temporary tables
You create an instance of a declared temporary table using the SQL statement
DECLARE GLOBAL TEMPORARY TABLE. That instance is known only to the
application process in which the table is declared, so you can declare temporary
tables with the same name in different applications. The qualifier for a declared
temporary table is SESSION.
Before you can define declared temporary tables, you must create a special
database and table spaces for them. You do that by running the CREATE
DATABASE statement with the AS TEMP clause, and then creating segmented
table spaces in that database. A DB2 subsystem can have only one database for
declared temporary tables, but that database can contain more than one table
space. There must be at least one table space with a 8-KB page size in the TEMP
database to declare a temporary table.
Example: The following statements create a database and table space for declared
temporary tables:
CREATE DATABASE DTTDB AS TEMP;
CREATE TABLESPACE DTTTS IN DTTDB
SEGSIZE 4;
You can define a declared temporary table in any of the following ways:
v Specify all the columns in the table.
Unlike columns of created temporary tables, columns of declared temporary
tables can include the WITH DEFAULT clause.
v Use a LIKE clause to copy the definition of a base table, created temporary
table, or view.
If the base table or created temporary table that you copy has identity columns,
you can specify that the corresponding columns in the declared temporary table
are also identity columns. Do that by specifying the INCLUDING IDENTITY
COLUMN ATTRIBUTES clause when you define the declared temporary table.
v Use a fullselect to choose specific columns from a base table, created temporary
table, or view.
Chapter 2. Working with tables and modifying data 23