EJB without primary key

Similar Questions

• You would design Tables without primary key?

  If you were asked to design a schema, if you create a table (however irrelevant) without a primary key? For example, a 'unprofessional' table such as a logging of errors table that records exceptions thrown from stored procedures, create you this table without a primary key?

  In a relational database you define und work with entities (tables) and you put in relationship to each other by joins. An entity must by definition always be identified by a unique key.
  If you don't know what kind of unique key identifies your entries in the table, it is almost certain that working from home in your datamodel and table designs had not been made. Your database objects contain tables, and they must have a unique identifier. Often it is a primary key (PK) composed of several columns.

  By definition a datamodel that contains the tables without primary keys is nomore a relational datamodel and one of the fundamental bases for the creation of a relational database is violated.

  Frankly I do not understand why Oracle allows the tables without primary key. Another system such as SAP R/3 are more stringent. Primary keys are required in the SAP and believe, when starting, it is sometimes tedious to define the primary key structures, but it's the basis of designing together relational datamodel you will put in place. You now SAP is based often on a DB ORACLE layer. They could do it, and these "extend" their functionality. But they are smart guys in Walldorf, and they always refrained to do. It's a good guess to believe, they have a good reason for it.

  Tables without primary key are NO relational tables, they are dungpiles. As Oracle needs priimary key itself in order to operate a relational database, ROWID have been defined. ROWID is the primary keys of the tables where the customer does not have a PK. But nice as ORACLE is, they strongly recommend not to use these ROWID in the application or database layer. ROWID is no identifier object that are stable in time and space (eg. two different databases in a distributed design oder a DEV and PROD-system).

  Definition of PK implies certain rules for the programming of your application and your DML operations. Especially you often MERGE in a relational table instead of simply INSERT'ing piece in a dungpile.

  When it later on with SELECT large datavolumes dataaccess, again the differences between well-defined joins (all based on the PK-relations) and joins non-unique keys will be the order of magnitude. Not only that, the latest degrades in performance much more quickly with the growth of result sets. When you start fumbling with no UNIQUE INDEXES, speed up performance in the operations of dungpiling you are already closer to hell than on a sunny day in the world of relational data.

  Othmar Lippuner
  SQL Reporting professional

• Get 2 amounts of 2 columns of 2 tables without primary key

  I would like to get the sum of column A of table 1 and the sum of column D in table 2 without using the primary key.

  Because I can't link the two tables, the only corresponding value is not the primary key.

  TABLE 1

  COLUMN A.     COLUMN B |    COLUMN C

  PAID NUMBER DESCRIPTION

  15472 blabla1 S15-875

  18515

  S15-875 blabla1

  215526.52 blabla2 D17-517

  ...                               ...                           ...

  TABLE 2

  COLUMN D |     COLUMN E |    COLUMN F

  INVOICE

  NUMBER

  DESCRIPTION

  185525 blabla1 S15-875

  158520 D17-517 blabla2

  8964

  D17-517

  blabla2

  I would like to see the number, the sum of which should be paid and what has been paid.

  But as you can see, you can pay in several times and there may be several invoices.

  There is therefore no link between two tables which is a primary key in both entities.

  No idea how I could get it?

  NUMBER |    DESCRIPTION |    BILL |     PAID

  S15-875 185525 33987 blabla1

  D17-517 blabla2 167484 215526.52

  The tables can be attached on «NUMBER», regardless of weather conditions, as a primary key is defined.

  sql> with table_1 as
    2    (         select 15472     as paid, 'S15-875' as "NUMBER", 'blabla1' as description from dual
    3    union all select 18515     as paid, 'S15-875' as "NUMBER", 'blabla1' as description from dual
    4    union all select 215526.52 as paid, 'D17-517' as "NUMBER", 'blabla2' as description from dual
    5    )
    6  , table_2 as
    7    (         select 185525    as invoice, 'S15-875' as "NUMBER", 'blabla1' as description from dual
    8    union all select 158520    as invoice, 'D17-517' as "NUMBER", 'blabla2' as description from dual
    9    union all select 8964      as invoice, 'D17-517' as "NUMBER", 'blabla2' as description from dual
   10    )
   11  select t1."NUMBER"     as "NUMBER"
   12  ,      t1.description  as description
   13  ,      ( select sum(t2.invoice) from table_2 t2 where t2."NUMBER" = t1."NUMBER" ) as invoice
   14  ,      sum(t1.paid)    as paid
   15  from   table_1 t1
   16  group by t1."NUMBER"
   17  ,        t1.description
   18  /
  
  NUMBER  DESCRIP    INVOICE       PAID
  ------- ------- ---------- ----------
  D17-517 blabla2     167484  215526.52
  S15-875 blabla1     185525      33987
  

  BTW: 'NUMBER' is a horrible name for a column. I strongly recommend to change something that is not a reserved word.

• Potential problems for tables without primary keys and unique keys

  GoldenGate 11.2.1.0.3/Solaris 10
  DB: Oracle for Oracle (Source and target is 11.2.0.3)
  Topology: unidirectional
  
  
  In our one-way configuration GG, little of the tables being replicated is not a primary key or a Unique key.
  
  Last week when we have implemented GG for the test, we received warnings for these table below.
  

  GGSCI > add trandata WMHS_UD.crtn_dtl
  
  2013-01-12 11:34:33  WARNING OGG-00869  No unique key is defined for table 'CRTN_DTL'. All viable columns will be used to represent the key, but may not guarantee uniqueness.  KEYCOLS may be used to define the key.
  
  Logging of supplemental redo data enabled for table WMHS_UD.crtn_dtl.

  Replication seems to work very well for these tables.
  
  Googling, I think that there may be performance degradation when you replicate tables without PK or the United Kingdom.
  
  But are there other potential problems such as data of a certain kind not replicated to the lack of PK/UK?

  It really depends on the data.

  By default, GG is combining all columns as a virtual primary key but don't no conflict control by default. So when you can be sure that the record you insert into the table is unique, then it will work.
  BUT as soon as you insert the same record, which is already inserted, then you will encounter problems.

  Let me show what happens when you use an initial charge because it makes it easier to describe:
  We start at 10:00 the capture for a table. Now, you insert a record at 10:00 in the tables. When you now start an initial charge to 10.02, then check you have inserted in the database to 10.01 will be repeated two times. During the IPL as the initial charge is made to 10.02 and it includes data of 10.01 AND it will be replicated again through the process of capture/replicate.

• Find tables without primary keys

  DB version: 10g Release 2
  
  We have several tables that do not have a primary key.
  
  I need to use USER_CONSTRAINTS view to find which of these tables that do not have a primary key.
  The following query will not work because there obviously returns all records where CONSTRAINT_TYPE! = « P »
  

  select table_name from user_Constraints WHERE constraint_type != 'P'

  I need to jump those table_names who have at least one occurrence of CONSTRAINT_TYPE = 'P '.

  Select table_name from user_tables where table_name
  not in
  (
  Select the table table_name from user_constraints where constraint_type = 'P '.
  )

• DB sequence for the primary key

  Hello

  I have Table of key primary we use DB sequence in the database itself, for example if start a line (using sql client) DB without primary key sequence will do it for me, because of this trigger.

  (1) my doubt is if I generate A EO off this table I need to explicitly set db sequence for this attribute as this or no need to do this sequence bz DB does good for me!

  (new oracle.jbo.server.SequenceImpl("SEQ_NAME",adf.object.getDBTransaction())).getSequenceNumber()
  
  
  
  

  No, you use a db trigger all what you need to do is to define the type of the attribute DBSeqence. Then the framework will assign a negative value for the PK, which can and will be used as K until you commit the transaction. During this time the bed frame now generated correct sequence of relaxation and rights holders to PK all negative values of the line (and it's child row).

  Don't forget to check DBSequence attributes must have "Refresh on insert" together that it triggers the correct PK is read from the database after insertion.

  Do not use ' (new oracle.jbo.server.SequenceImpl ("SEQ_NAME", adf.object.getDBTransaction ()) .getSequenceNumber () ' attribute is the PK you use triggers to generate the sequence.

  Timo

• create materialized view log on the table without a primary key

  Hi all

  CREATE TABLE client_months 
  (
    SUBJ_CODE         NUMBER(4),
    SERV_CODE         NUMBER(4),
    DEBIT_CODE        NUMBER(4),
    PERIOD_NUM        NUMBER(2),
    PERIOD_NAME       VARCHAR2(40 CHAR),
    FIRST_MON_DAY     DATE,
    LAST_MON_DAY      DATE,
    VALUE_MON_DAY     DATE,
    MONTHES           NUMBER(4,2),
    GARDENING_WEIGHT  NUMBER(5,4),
    REASON_CODE       NUMBER(5),
    STAMP_ACTION      VARCHAR2(1 CHAR),
    STAMP_CDATE       DATE                        DEFAULT SYSDATE,
    STAMP_DATE        DATE,
    STAMP_USER        VARCHAR2(15 CHAR),
    REGION_CODE       NUMBER(9)
  )
  table created.
  
  CREATE UNIQUE INDEX client_months_UK  ON client_months 
  (SUBJ_CODE, SERV_CODE, DEBIT_CODE, PERIOD_NUM, REGION_CODE)
  index created.
  
  CREATE MATERIALIZED VIEW LOG ON client_months with rowid;
  
  CREATE MATERIALIZED VIEW client_months_mv 
  BUILD immediate 
  REFRESH FAST ON COMMIT 
  AS 
  SELECT * FROM client_months;
  
  ORA-12014: table 'CLIENT_MONTHS' does not contain a primary key constraint

  I don't want to refresh the mview when validation is performed on the base table.
  And I don't want to change the base table by adding a primary key.
  
  is it possible to create the mview journal using the unique index? or another solution?
  Please help
  Thanks in advance
  Naama

  Naamas wrote:
  No,
  I already read this post!

  Then you read wrong:

  SQL> CREATE TABLE client_months
    2  (
    3    SUBJ_CODE         NUMBER(4),
    4    SERV_CODE         NUMBER(4),
    5    DEBIT_CODE        NUMBER(4),
    6    PERIOD_NUM        NUMBER(2),
    7    PERIOD_NAME       VARCHAR2(40 CHAR),
    8    FIRST_MON_DAY     DATE,
    9    LAST_MON_DAY      DATE,
   10    VALUE_MON_DAY     DATE,
   11    MONTHES           NUMBER(4,2),
   12    GARDENING_WEIGHT  NUMBER(5,4),
   13    REASON_CODE       NUMBER(5),
   14    STAMP_ACTION      VARCHAR2(1 CHAR),
   15    STAMP_CDATE       DATE                        DEFAULT SYSDATE,
   16    STAMP_DATE        DATE,
   17    STAMP_USER        VARCHAR2(15 CHAR),
   18    REGION_CODE       NUMBER(9)
   19  )
   20  /
  
  Table created.
  
  SQL> CREATE UNIQUE INDEX client_months_UK  ON client_months
    2  (SUBJ_CODE, SERV_CODE, DEBIT_CODE, PERIOD_NUM, REGION_CODE)
    3  /
  
  Index created.
  
  SQL> CREATE MATERIALIZED VIEW LOG ON client_months with rowid
    2  /
  
  Materialized view log created.
  
  SQL> CREATE MATERIALIZED VIEW client_months_mv
    2  BUILD immediate
    3  REFRESH FAST WITH ROWID ON COMMIT -- pay attention to WITH ROWID
    4  AS
    5  SELECT * FROM client_months
    6  /
  
  Materialized view created.
  
  SQL>
  

  SY.

• create view materized without constraint primary key on the base table?

  Hello
  
  I tried to create a materized view, but I got this error:
  
  SQL > CREATE MATERIALIZED VIEW FAST REFRESH TABLE1_MV
  START BY
  TO_DATE (April 25, 2009 03:00:13 ',' DD-MM-YYYY hh24:mi:ss')
  NEXT
  SYSDATE + 1
  AS
  Select * from TABLE1@remote_db
  SQL > /.
  CREATE MATERIALIZED VIEW FAST REFRESH TABLE1_MV
  *
  ERROR on line 1:
  ORA-12014: table 'TABLE1' does not contain a primary key constraint.
  
  Table1 in remote_db is not a primary key constraint. Is there anyway that I can create a view materized on a base table that is not a primary key constraint?
  
  Thank you
  Liz

  Make sure user name used in remote_db database link has select privileges on Journal of MV. On the issue of db source:

  SELECT LOG_TABLE FROM DBA_MVIEW_LOGS WHERE LOG_OWNER = 'TABLE1-owner' AND MASTER = "TABLE1";

  This will give you MV table the journal name. On the issue of target side:

  SELECT * from MV-LOG-NAME@remote_db;

  And after your version.

  SY.

• Trigger - use one to create primary key values

  I'm stuck on a simple use to do a TRIGGER that fires when you add new rows to a table and want to Developer SQL to add the primary key value.

  I seem to be able to relax, but it is not inserted the primary key but giving a SQL error: ORA-00947: not enough values.

  Here's what I have.

  CREATE TABLE HF_fishers

  (

  contact_id INT NOT NULL

  , name VARCHAR (25)

  , last_name VARCHAR (35)

  PRIMARY KEY (contact_id)

  );

  CREATE SEQUENCES HF_fishers_seq.

  Then I ran the following trigger:

  CREATE

  HF_fishers_seq_trigger RELAXATION

  BEFORE INSERTING

  ON HF_fishers

  FOR EACH LINE

  BEGIN

  IF (: new.contact_id IS NULL)

  THEN

  : NEW.contact_id: = NVL (: NEW.contact_id)

  HF_fishers_seq. NEXTVAL

  );

  END IF;

  END HF_fishers_seq_trigger;

  =============

  Then I executed the following SQL statement that gives the error.

  INSERT INTO HF_fishers VALUES('Jacob','Muller');

  But if I do everything is good except that it defeats the purpose of relaxation.

  INSERT INTO HF_fishers VALUES(1,'Jacob','Muller');

  MySQL has a nice 'AUTO_INCREMENT' command, but from what I understand in Oracle, I need to set up a trigger to automatically increment a column/cell, which in this case I use for the PRIMARY KEY.

  3003916 wrote:

  OK Jaramillo, I tried as you wrote, but what would be an INSERT statement correct?

  -After the code trigger of Jaramillo

  INSERT INTO HF_fishers (first_name, last_name) values ("Jesse", "Owens"); -I have the trigger but he made the mistake of duplicate key.

  INSERT INTO HF_fishers values (hf_fishers_seq.nextval, 'Jesse', "Owens");  -No trigger but get key duplicated,.

  INSERT INTO HF_fishers VALUES(:NEW_contact_id,'Jesse','Ownes'); -works without the trigger but the "get links" dialog box appears. So not much 'automatic' on this issue,.

  My mistake.  Here is the modified version of the trigger. I removed the CONDITIONAL clause and comes to be a part of the body of the trigger.

  So, I created the table, the sequence, the relaxation and ran the first two insert statements and it worked fine.  The third one you have invites SQL + or any tool you use to enter a value if she sees the ":" colon as a variable binding.  Colon only works in a trigger without asking for confirmation.

  Here is the code and my exit I ran home

  DROP TABLE hf_fishers CASCADE CONSTRAINTS PURGE;
  DROP SEQUENCE hf_fishers_seq;
  
  CREATE TABLE hf_fishers
  (
  contact_id   INTEGER NOT NULL
  ,first_name   VARCHAR(25)
  ,last_name    VARCHAR(35)
  ,PRIMARY KEY (contact_id)
  );
  
  CREATE SEQUENCE hf_fishers_seq;
  
  CREATE OR REPLACE TRIGGER hf_fishers_seq_trigger
     BEFORE INSERT
     ON hf_fishers
     FOR EACH ROW
  BEGIN
  
     IF(:NEW.contact_id IS NULL) THEN
        :NEW.contact_id := hf_fishers_seq.NEXTVAL;
     END IF;
  
  END hf_fishers_seq_trigger;
  
  INSERT INTO hf_fishers(first_name, last_name)
       VALUES ('Jesse', 'Owens');  -- Works with the trigger
  
  INSERT INTO hf_fishers
       VALUES (hf_fishers_seq.nextval, 'Jesse', 'Owens');  --Works without using the trigger body code.
  
  SELECT *
    FROM hf_fishers;
  
  COMMIT;
  

  The output

  Deleted table.

  Elapsed time: 00:00:00.05

  Sequence has fallen.

  Elapsed time: 00:00:00.02

  Table created.

  Elapsed time: 00:00:00.03

  Order of creation.

  Elapsed time: 00:00:00.02

  Trigger created.

  Elapsed time: 00:00:01.05

  1 line of creation.

  Elapsed time: 00:00:00.04

  1 line of creation.

  Elapsed time: 00:00:00.01

  CONTACT_ID FIRST NAME LAST NAME

  ---------- ------------------------- -----------------------------------

  1 Jesse Owens

  2 Jesse Owens

  2 selected lines.

  Elapsed time: 00:00:00.04

  Validation complete.

  Elapsed time: 00:00:00.01

• Drop a primary key

  If it does not create an orphan can not drop us a primary key?

  My book says no.  Steve O'Hearn page text 1z0-047 432.

  For example, consider this code:

  CREATE TABLE CRUISE_ORDERS

  (NUMBER OF CRUISE_ORDER_ID,

  ORDER_DATE DATE,

  PK_CO (CRUISE_ORDER_ID, ORDER_DATE) PRIMARY KEY CONSTRAINT);

  CREATE TABLE ORDER_RETURNS

  (NUMBER OF ORDER_RETURN_ID,

  NUMBER OF CRUISE_ORDER_ID

  DATE OF CRUISE_ORDER_DATE,

  CONSTRAINT PK_OR PRIMARY KEY (ORDER_RETURN_ID).

  FOREIGN KEY CONSTRAINT FK_OR_CO

  (CRUISE_ORDER_ID, CRUISE_ORDER_DATE)

  REFERENCES CRUISE_ORDERS (CRUISE_ORDER_ID, ORDER_DATE));

  These SQL statements will create two tables with a FOREIGN KEY relationship

  linking them together - see Figure 11 - 1 for the model of data representing the

  relationship.

  In the CRUISE_ORDERS table that we just created, we cannot let down the CRUISE_

  ORDER_ID column or the ORDER_DATE column, for two different reasons:

  They are part of the PRIMARY KEY constraint and forced to columns

  cannot be deleted unless the constraint first fell;

  They are part of the key referred to in the FOREIGN KEY of another table.

  They cannot be deleted as long as a FOREIGN KEY constraint refers to them.

  Similarly, we cannot remove the column the table ORDER_RETURNS that

  is subject to the constraint PRIMARY KEY (ORDER_RETURN_ID), or the...

  Easily, you should be able to remove the column order_return_id. I did it myself. Only, I caught this post back to the chapter for a review and it made no sense to me. Perhaps because it refers to PL/SQL or an older version? (the book is 5 years old).

  In any case I do not see why a primary key without dependent columns could not be deleted.

  Like I said I tested it, and it can be moved.

  This isn't what the text says. It is said that if PK in question is mentioned by a FK, you can not remove the PK. If you take the part of the sentence on its own "BOLD", it is obviously fake.

• Primary key and foreign key between the different schemas

  Hi all;

  SCOTT user have a 'rank' of table-> it contains the primary key-> users tablespace

  The U1 user have a 'emp' table-> it contains the foreign key-> test tablespace

  U1 > select constraint_name, constraint_type, r_owner, owner, r_constraint_name of all_constraints where table_name = 'EMP ';

  OWNER CONSTRAINT_NAME C R_OWNER R_CONSTRAINT_NAME

  ------------ ------------------------------ - -------------------------- ----------------------- -----------------------------------------------------

  U1              EMP_EMPLEV_C12_FK R SCOTT GRADE_GRL_C1_PK

  If I have connection U1, no possibility to find the name of the primary key without connection scott table?

  Thank you

  Hello

  So, you want to know what picture of the SCOTT schema has the constraint that is named "GRADE_GRL_C1_PK." Isn't it?

  If so,.

  SELECT table_name

  Of all_constraints

  Owner WHERE = 'SCOTT '.

  AND the argument constraint_name = 'GRADE_GRL_C1_PK. '

  ;

• Add new ID/Primary Key column with custom ID generation

  I use Hibernate as ORM to interact with Oracle.

  This issue is no longer on the side of SQL to emulate the generator ID seqHiLo

  that we use to generate the primary key for tables, the column ID i.e.

  Now I want to add a new column to the ID of an already created table, and this table has data.

  I have a procedure to add the ID column in a table:

  For example:

  ALTER table TableName add (columnName NUMBER);

  Then create the sequence

  CREATE SEQUENCE SEQ_ID

  START WITH 1

  INCREMENT BY 1

  MAXVALUE 99999999

  MINVALUE 1

  NOCYCLE;

  and after that he use the UPDATE statement to insert some values into the column like this

  UPDATE tableName SET columnName is seq_test_id. NEXTVAL

  Here I intend to use hibernate_sequence, to be in harmony with the hibernation of generation mode the ID's

  The question is:

  UPDATE tableName SET columnName = hibernate_sequence. NEXTVAL, generates the ID in the order.

  However, I need identifiers according to the algorithm of seqHiLo.

  Is there a way to do this in pure SQL?

  In short, can we have a personalized way to generate IDS to use in the new column, rather than a sequential,

  as stated above?

  If you update every row of a session, it won't make any difference if you select from a sequence and use this value immediately (as in your example) or if you go through the algorithm of HiLo: be it you will end up with sequentially numbered lines without leaving space. Then after the update block of existing lines, you will need to create the sequence to be used by your Hibernate application with an initial value of your current value divided by the low value.

  If you really want to implement the algorithm of HiLo for the bulk loading, you can of course do so. But it is not necessary: the effect will be the same.

• Local primary key on reference partitioned Table

  Oracle running on Red Hat Linux Rel6 11.2.0.3.

  I'm on a closed network, so the following must be typed manually.

  I have a table of documents which is essentially the following:

  (entire annual <-primary key)

  whole Source_ID,

  load_dt date,

  date of doc_dt,

  doc_info clob,

  ...)

  which is partitioned on column source_id.

  I created a partitioned table of reference as follows:

  create table doc_entities_prt)

  whole doc_entity_id

  all annual,

  whole entity_id,

  forced doc_ent_fk (annual) references to documents (annual)

  tablespace...

  allow the movement of the line

  benchmark score (doc_ent_fk);

  The annual column in the child table is not unique.  The doc_entity_id column is unique.  I want to set the primary key on doc_entities_prt as a local index on the doc_entity_id column.  I was not able to find the proper syntax to get there, and now I'm wondering if this is even possible? Any ideas appreciated.

  Oops, I missed part that you want to base the PK of this index. No, it is not possible and has nothing to do with the partitoning reference. A unique index can be partitioned only if it includes a partitioning column. You can create a non-unique without partitioning column partitioned index, but then you can't create PK supported by such an index for the same reason - oracle would not be able to verify uniquenes based on this index partition and controls of the cross-partition are not supported:

  SQL > create table documents)
  2 whole annual,
  3 whole source_id,
  load_dt date 4.
  date of doc_dt 5.
  6 doc_info clob
  7                        )
  8 partition by range (source_id)
  9      (
  10 partition p1 values less than (10),
  11 partition p2 values less than (100)
  12)
  13.

  Table created.

  SQL > create index unique documents_pk
  2 on documents (annual)
  (3) local
  partition 4 p1,
  5 partition p2
  6         )
  7.
  on documents (annual)
  *
  ERROR on line 2:
  ORA-14039: partitioning columns must be a subset of the columns of a unique key
  index

  SQL > create index documents_pk
  2 on documents (annual)
  (3) local
  partition 4 p1,
  5 partition p2
  6         )
  7.

  The index is created.

  SQL > alter table documents
  2 Add the constraint documents_pk
  3 key (annual) elementary school
  4 using index documents_pk
  5.
  change the documents table
  *
  ERROR on line 1:
  ORA-14196: specified Index cannot be used to apply the constraint.

  SQL >

  SY.

• Order columns (which make up the primary key constraint) matter in where clause of DML query for use of indexing mechanism to operate.

  Version of DB: database Oracle 11 g Enterprise Edition Release 11.2.0.3.0 - 64 bit Production

  
  I have a table my_table as below:
  create table my_table
  (
  my_code varchar2 (6).
  my_id varchar2 (24).
  forced pk_1 primary key (my_code, my_id)
  );

  
  Primary_key here's a composite key that contains columns 1 (my_code) and 2 (my_id).
  Is there that a difference in the way below queries is executed in terms of performance (use of indexing in the extraction).

  (a) select * from my_table where my_code = '123' and my_id = "456";
  (b) select * from my_table where my_id = '456' and my_code = '123';

  
  The understanding I have the order of the column in the where clause should be identical to the sequence in
  What primary key draws for indexing to be used by oracle in oracle other DML queries ignores indexing
  However when I used explain plain both show the same query cost with single scan with index rowid.
  so I don't know if I'm wrong in the concept that I have. Kindly help.

  Thanks in advance,
  Gerard

  Your question is answered in the Performance Tuning Guide

  Using indexes and clusters

  14.1.4 choosing composite indexes

  A composite index contains several key columns. Composite indexes can provide additional benefits compared to the index to single column:

  • Improved selectivity

    Sometimes the two or more columns or expressions, each with a low selectivity can be combined to form a composite with a high selectivity.

  • Reduced IO

    If all columns selected by a query are a composite index, then Oracle may return these values in the index without access to the table.

  A SQL statement can use a path on a composite index if the statement contains constructions that use a main part of the index.

  Note:

  This is no longer the case with the skip index scans. See "Index Skip Scans".

  A main part of an index is a set of one or more columns that have been specified first and consecutively in the list of columns in the CREATE INDEX statement that created the index.

• How to generate the primary key element and move to another page?

  How to make the primary key value to another page in a table?

  

  Hello

  I am a beginner in the apex,

  Please, now I want to add the primary key to page 1 for item id in page 2...

  Notice:

  Before, I created (process of pl/sql in the rendering of page @ after the header section) to get the id of secuance.

  BEGIN
  :P17_ID := seq_t_items_id.NEXTVAL;
  END;
  
  
  

  primary key is generated for the element ID of page 1... BUT When I update 'page 1' I see error and solved when shut down my browser and open it again...

  Please help me to...

  1. Generate a primary key (article id @ page 1)... without refresh error. ?
  2. Pass him (item_id) on page 2

  Thank you all for...

  Sorry I'm beginner in apex,

  I don't know how Pass value of the item_id TO page 1 page 2 "in the form ID", turn to the first PHOTO... .
  Help me..

  Thank you