Create Temporary Tables in Oracle

Global Temporary Tables in Oracle

Temporary tables are useful in applications where a result set is to be buffered, perhaps because it is constructed by running multiple DML operations. For example, consider the following:

A Web-based airlines reservations application allows a customer to create several optional itineraries. Each itinerary is represented by a row in a temporary table. The application updates the rows to reflect changes in the itineraries. When the customer decides which itinerary she wants to use, the application moves the row for that itinerary to a persistent table.

During the session, the itinerary data is private. At the end of the session, the optional itineraries are dropped.

This statement creates a temporary table that is transaction specific:

NOTE : Indexes can be created on temporary tables. They are also temporary and the data in the index has the same session or transaction scope as the data in the underlying table.

*********************************************************************************
HERE is an example to create a global temporary table with on commit DELETE ROWS :
*********************************************************************************

sql>  CREATE GLOBAL TEMPORARY TABLE admin_work_area
        (startdate DATE,
         enddate DATE,
         class CHAR(20))
      ON COMMIT DELETE ROWS;
     
     
   
sql>  insert into ADMIN_WORK_AREA values (sysdate,sysdate+ 1,'A');

1 row inserted.


sql> select * from ADMIN_WORK_AREA;

commit;

Commit complete.

sql> select * from ADMIN_WORK_AREA;


NOTE: records in this temp table will be deleted upon commit. This is equivalent to truncating table on commit.

*********************************************************************************
HERE is an example to create a global temporary table with on commit PRESERVE ROWS :
*********************************************************************************


sql>  CREATE GLOBAL TEMPORARY TABLE admin_work_area
        (startdate DATE,
         enddate DATE,
         class CHAR(20))
      ON COMMIT PRESERVE ROWS;
     
           
sql>  insert into ADMIN_WORK_AREA values (sysdate,sysdate+ 1,'A');

1 row inserted.

1 row inserted.

sql>  select * from ADMIN_WORK_AREA;

commit;

Commit complete.

sql>  select * from ADMIN_WORK_AREA;


NOW exit the session and login back and select the table.

sql>  select * from ADMIN_WORK_AREA;

table is empty

NOTE: records (rows) in this temp table will be deleted upon session exit only, as long as you are using same session you can see these rows.
This is equivalent to truncating table on session exit.

Inserting Data into table with DML Error Logging (catching errors whiles inserting data into table)

 Inserting Data with DML Error Logging:

When you load a table using an INSERT statement with sub query, if an error occurs, the statement is terminated and rolled back in its entirety. This can be wasteful of time and system resources. For such INSERT statements, you can avoid this situation by using the DML error logging feature.

To use DML error logging, you add a statement clause that specifies the name of an error logging table into which the database records errors encountered during DML operations. When you add this error logging clause to the INSERT statement, certain types of errors no longer terminate and roll back the statement. Instead, each error is logged and the statement continues. You then take corrective action on the erroneous rows at a later time.

DML error logging works with INSERT, UPDATE, MERGE, and DELETE statements. This section focuses on INSERT statements.

--------------------------------------------------------
--  DDL for Table ATEST1
--------------------------------------------------------

  CREATE TABLE "ATOORPU"."ATEST1"
   (    "ID" NUMBER constraint ATEST1_PK PRIMARY KEY,
    "TDATE" DATE,
    "AMOUNT" VARCHAR2(20 BYTE),
    "ORD_NO" NUMBER
   ) ;

--------------------------------------------------------
INSERT SOME VALUES INTO TEST TABLE
--------------------------------------------------------

Insert into ATEST1 (ID,TDATE,AMOUNT,ORD_NO) values (1,to_date('04-APR-16','DD-MON-RR'),null,300);
Insert into ATEST1 (ID,TDATE,AMOUNT,ORD_NO) values (2,to_date('04-APR-16','DD-MON-RR'),null,300);
Insert into ATEST1 (ID,TDATE,AMOUNT,ORD_NO) values (3,to_date('01-MAR-16','DD-MON-RR'),null,100);
Insert into ATEST1 (ID,TDATE,AMOUNT,ORD_NO) values (4,to_date('01-MAR-16','DD-MON-RR'),'100',200);

--------------------------------------------------------
CREATE ERROR LOG TABLE USING THE DBMS PACKAGE :
--------------------------------------------------------

EXECUTE DBMS_ERRLOG.CREATE_ERROR_LOG('ATEST1', 'ERR_ATEST1');   -- ATEST1 source table and ERR_ATEST1 error log table


Error Logging Restrictions and Caveats:

• Oracle Database logs the following errors during DML operations:
• Column values that are too large
• Constraint violations (NOT NULL, unique, referential, and check constraints)
• Errors raised during trigger execution
• Errors resulting from type conversion between a column in a subquery and the corresponding column of the table
• Partition mapping errors

Certain MERGE operation errors (ORA-30926: Unable to get a stable set of rows for MERGE operation.)

--------------------------------------------------------
-- This will generate some insert errors
--------------------------------------------------------

INSERT INTO ATEST1
  SELECT ID+3,TDATE,AMOUNT,ORD_NO
  FROM ATEST1
  WHERE id > 1
  LOG ERRORS INTO ERR_ATEST1 ('daily_load') REJECT LIMIT 9; 

--- daily_load is TAG, REJECT LIMT will set the max errs before terminating insert statement.


Note:
 
If the statement exceeds the reject limit and rolls back, the error logging table retains the log entries recorded so far.

--------------------------------------------------------
-- This will generate some update errors
--------------------------------------------------------

update ATEST1 set ID=3 where ID>5 LOG ERRORS INTO ERR_ATEST1 ('daily_load') REJECT LIMIT 9;

--- daily_load is TAG, REJECT LIMT will set the max errs before terminating insert statement.


--------------------------------------------------------
LETS CHECK THE ERROR MESSAGES RECORDED:
--------------------------------------------------------

select * from ERR_ATEST1;

USING SELECT 'X' in query/sub-queries

USING SELECT 'X' in query/sub-queries.

--------------------------------------------------------
--  DDL for Table TAB1
--------------------------------------------------------

  CREATE TABLE "ATEST"."TAB1"
   (    "ID" NUMBER,
    "NAME" VARCHAR2(20 BYTE)
   ) ;

Insert into ATEST.TAB1 (ID,NAME) values (1,'AAA');
Insert into ATEST.TAB1 (ID,NAME) values (2,'BBB');
Insert into ATEST.TAB1 (ID,NAME) values (3,'EEE');
Insert into ATEST.TAB1 (ID,NAME) values (4,'FFF');


--------------------------------------------------------
--  DDL for Table TAB2
--------------------------------------------------------

  CREATE TABLE "ATEST"."TAB2"
   (    "ID" NUMBER,
    "NAME" VARCHAR2(20 BYTE)
   ) ;

Insert into ATEST.TAB2 (ID,NAME) values (1,'CCC');
Insert into ATEST.TAB2 (ID,NAME) values (2,'DDD');


Get records that exits in TAB1 and not in TAB2 using select 'X' :

select * from TAB1 f where not exists (select 'X' from TAB2 where id=f.id);
ID    NAME
--    ---- 
4    FFF
3    EEE

IN the above query we get output of all the records from TAB1 that doesnt match with TAB2 ID's.
Hence we do not get the records with ID's 1 & 2 as they only exits in TAB1.
This is just like using "select * from TAB1 f where not exists (select ID from TAB2 where id=f.id);"


Get records that exits in TAB1 and in TAB2 using select 'X' :

select * from TAB1 f where exists (select 'X' from TAB2 where id=f.id);

ID    NAME
--    ---- 
1    AAA
2    BBB

IN the above query we get output of all the records from TAB1 that exist with same ID in TAB2 .
Hence we get only records with ID 1 & 2 as they exists in both TABLES.
This is just like using "select * from TAB1 f where exists (select ID from TAB2 where id=f.id);"