Number of unique key in a table column

Similar Questions

• Why we cannot create more than one primary key on a table. Why we create several unique key on a table. Please explain if anyone have details of this.

  Why we cannot create more than one primary key on a table. Why we create several unique key on a table. Please explain if anyone have details of this.

  «a primary key has semantic meaning, it is to be immutable (never change of value), unique and not null.»

  a unique constraint is simply "at any time, these values are unique - they can change and they can be null.

  You use a unique when constraint

  (a) you do not already have a primary key for a table can have only one
  (b) you allow NULL values in attributes
  "(c) to allow you to update the values in the attributes.

  https://asktom.Oracle.com/pls/Apex/f?p=100:11:0:P11_QUESTION_ID:5541352100346689891

• primary or unique key

  I have to design a new "dummy" table, which must include a work_flow_identifier.
  
  I need a work_flow_identifier with the structure
  ' department_no/financial-system/year/sequence-no' like for example 0, RLVS, 09, 48
  
  (department_no is a primary key in the table and financial_system Department
  a primary key in table systems).
  
  Create a key primary varchar for this work_flow_identifier, because it is
  accurate identification?
  
  Or it is better to create a unique key?
  

  table dummy 
  -----------
  wk_pk               number(12);
  work_flow_identifier     varchar(30);

  -> unique key: wk_pk and work_flow_identifier?
  or

  table dummy 
  -----------
  work_flow_identifier     varchar(30);

  -> key priary: work_flow_identifier?
  
  Does anyone have an idea?

  Whence your workflow identifier? Is it stored somewhere in the 0RLVS0948 format, or is it built to individual fields in another table somewhere, or entry to a form?

  If it is stored in a table in this format, and then, if possible, I would like to change the table where it is stored to store four discrete fields.

  If this is not possible, I reluctantly (very very reluctantly) to add another column to dummy to hold the values concatenated as a discrete value but essentially meaningless.

  Another possibility would be to build a function index values concatenated in addition to the unique constraint on the four fields to accommodate seeks a workflow identifier.

  If the workflow identifier is constructed on the fly, then simply pass the discrete values instead of concatenate.

  John

• Disable the unique key constraint

  Hello
  
  Is it possible to disable a unique key constraint?
  I tried the following code:
  
  ALTER TABLE table_name
  DISABLE the CONSTRAINT uk_constraint_name
  
  that seems to work fine, but when I try to insert or update a record that the unique constraint is still on. However, Toad in the United Kingdom is marked as disabled.
  
  What do I need to drop the UK and re-create it after my updates?
  
  Thank you

  The behavior that I have demonstrated that during
  a. you have an existing UNIQUE Index
  b. you add a Unique key constraint (with the same or another name, any - except that the error message contains the name of the index is different, if the constraint is disabled)

  OTOH, if you set the Unique key on the table without pre-existing index constraint, Oracle creates an Index. If you disable this constraint, Oracle removes the Index.
  So, if it is a small table and you can afford to recreate the Index each time, you can follow this method.

  SQL> create table t_2 (col_1 number, col_2 varchar2(5));
  
  Table created.
  
  SQL> alter table t_2 add constraint t_2_uk unique (col_1);
  
  Table altered.
  
  SQL> select index_name, uniqueness, status from user_indexes where table_name = 'T_2';
  
  INDEX_NAME                     UNIQUENES STATUS
  ------------------------------ --------- --------
  T_2_UK                         UNIQUE    VALID
  
  SQL> insert into t_2 values (1,'a');
  
  1 row created.
  
  SQL> commit;
  
  Commit complete.
  
  SQL> alter table t_2 disable constraint t_2_uk;
  
  Table altered.
  
  SQL> insert into t_2 values (1,'b');
  
  1 row created.
  
  SQL> select index_name, uniqueness, status from user_indexes where table_name = 'T_2';
  
  no rows selected
  
  SQL>SQL> select constraint_name, constraint_type, status from user_constraints where table_name = 'T_2';
  
  CONSTRAINT_NAME                C STATUS
  ------------------------------ - --------
  T_2_UK                         U DISABLED
  
  SQL> alter table t_2 enable constraint t_2_uk;
  alter table t_2 enable constraint t_2_uk
  *
  ERROR at line 1:
  ORA-02299: cannot validate (AWRADMIN.T_2_UK) - duplicate keys found
  
  SQL> delete t_2 where col_2 = 'b';
  
  1 row deleted.
  
  SQL> alter table t_2 enable constraint t_2_uk;
  
  Table altered.
  
  SQL> select index_name, uniqueness, status from user_indexes where table_name = 'T_2';
  
  INDEX_NAME                     UNIQUENES STATUS
  ------------------------------ --------- --------
  T_2_UK                         UNIQUE    VALID
  
  SQL>
  

  Hemant K Collette

• Two foreign keys of a table in a single column

  Hi gurus

  I wonder that can we add two foreign keys of a table on a single column, I think the answer is, but what should be the reason behind this?

  Appreciate if someone there explain to me...

  Concerning

  Muzz

  Hello Muzz,

  Perhaps the example of human Chen reveals a design error.
  If a student has a 'teacher_id' "teacher" FK and FK for "emp" becaue each teacher is an EMP, I guess that the correct design would be to have only the FK of 'teacher' and to have another pointing to the 'emp' table in the 'teacher' tabe FK

  But we can imagine comical situations...
  CREATE TABLE PEOPLE (id NUMBER of KEY PRIMARY, name VARCHAR2 (20 CHAR),...);
  CREATE TABLE SCIENTIST (id people KEY PRIMARY NUMBER (id) REFERENCES, discipline VARCHAR2 (20 CHAR),...);
  CREATE TABLE POLICEMAN (id REFERENCES to KEY PRIMARY NUMBER (id), hire_date people DATE,...);

  First table = all.
  2nd: a subset of the first, with people having the profile of 'scientific '...
  3rd: a subset of the first, with people being a policeman.
  It might be people first table and in none of the 2nd and 3rd, 1st and 2nd, 1st and 3rd only or in the 3 tables.

  Then we can have a fourth table of 'something' referring to a person who must be a scientist and a police officer.

  Here is a sqlplus session illustrating; the last piece: I try inserting several lines in xxxx, only the last is accepted.

  SQL > CREATE TABLE PEOPLE (id NUMBER of the PRIMARY KEY, name VARCHAR2 (20 CHAR));
  Table created.

  SQL > CREATE TABLE SCIENTIST (people of REFERENCES of KEY PRIMARY NUMBER id (id), discipline VARCHAR2 (20 CHAR));
  Table created.

  SQL > CREATE TABLE POLICEMAN (people of REFERENCES of KEY PRIMARY NUMBER id (id), DATE hire_date);
  Table created.

  SQL > CREATE TABLE XXXX (id PRIMARY KEY NUMBER, people_id NUMBER, any other VARCHAR2 (30 CHAR));
  Table created.

  SQL > ALTER TABLE ADD CONSTRAiNT fk_xxsci FOREIGN KEY (people_id) scientific xxxx REFERENCES (id);
  Modified table.

  SQL > ALTER TABLE ADD CONSTRAiNT fk_xxpol FOREIGN KEY (people_id) police xxxx REFERENCES (id);
  Modified table.

  SQL > INSERT INTO person VALUES (100, 'John');
  1 line of creation.

  SQL > INSERT INTO person VALUES (120, 'Mary');
  1 line of creation.

  SQL > INSERT INTO person VALUES (103, 'Tom');
  1 line of creation.

  SQL > INSERT INTO person VALUES (123, "Bruno");
  1 line of creation.

  SQL > INSERT INTO VALUES of scientific (120, 'Chemistry');
  1 line of creation.

  SQL > INSERT INTO scientific VALUES (123, 'Mathematics');
  1 line of creation.

  SQL > INSERT INTO VALUES of policeman (103, DATE ' 2001-04-01');
  1 line of creation.

  SQL > INSERT INTO VALUES of policeman (123, DATE ' 1998-07-01');
  1 line of creation.

  SQL > INSERT INTO xxxx VALUES (1, 456, "nothing");
  ERROR on line 1:
  ORA-02291: integrity constraint (SYS. FK_XXPOL) violated - key parent not found

  SQL > INSERT INTO xxxx VALUES (1, 100, "only to people");
  ORA-02291: integrity constraint (SYS. FK_XXPOL) violated - key parent not found

  SQL > INSERT INTO xxxx VALUES (1, 120, "only the learned");
  ORA-02291: integrity constraint (SYS. FK_XXPOL) violated - key parent not found

  SQL > INSERT INTO xxxx VALUES (1, 103, "only police officer");
  ORA-02291: integrity constraint (SYS. FK_XXSCI) violated - key parent not found

  SQL > INSERT INTO xxxx VALUES (1, 123, 'ok');
  1 line of creation.

  Best regards

  Bruno Vroman.

• table partitioned and unique keys

  I really don't understand why Oracle does not apply in some cases, unique keys.

  Let's say I have a table

  create table t (t_type not null, t_key not null, id not null, not null value)

  list partition (t_type)

  (

  type1 partition values ('ppp1"),

  rest of partition (default) values

  ) as

  Select "ppp" | rownum, rownum, rownum, rownum of double connect by rownum < = 100;

  And following changes in the indices for unique keys

  -1

  create index idx_1 on t (t_key, id);

  ALTER table t add constraint t_uk unique (t_key) using index idx_1;

  ALTER table drop constraint t_uk drop index;

  -2

  create index idx_1 on t (t_key, id, t_type);

  ALTER table t add constraint t_uk unique (t_key) using index idx_1;

  ALTER table drop constraint t_uk drop index;

  -3

  create index idx_1 on t (t_key, id, t_type) local;

  ALTER table t add constraint t_uk unique (t_key) using index idx_1;

  Drop index idx_1;

  -4

  create an index only idx_1 on t (t_key, id);

  ALTER table t add constraint t_uk unique (t_key) using index idx_1;

  Drop index idx_1;

  -5

  create an index only idx_1 on t (t_key, id, t_type);

  ALTER table t add constraint t_uk unique (t_key) using index idx_1;

  Drop index idx_1;

  -6

  create an index only idx_1 on t (t_key, id, t_type) local;

  ALTER table t add constraint t_uk unique (t_key) using index idx_1;

  Drop index idx_1;

  -7

  create index idx_1 on t (t_key, t_type, id) local;

  ALTER table t add t_uk unique constraint (t_key, t_type) using index idx_1;

  ALTER table drop constraint t_uk drop index;

  -8

  create an index only idx_1 on t (t_key, t_type, id) local;

  ALTER table t add t_uk unique constraint (t_key, t_type) using index idx_1;

  Drop index idx_1;

  I got the set of questions:

  1. first and second cases were performed with success while 4th and 5th failed.

  The only difference is that the overall index in 4th and 5th cases are unique.

  It is unclear why ' ORA-14196: specified index cannot be used to apply the constraint. ' has occurred.

  2. in the third case index is similar to that in second place with the only difference that it is local.

  Still, it is not clear why it failed with ORA-14196.

  3 and the last question why ORA-14196 arose in 8 cases, while the 7th, it didn't.

  The only difference is the local index in 8 cases is unique.

  Thank you

  Hi Alex

  (1) index 4 and 5 cannot be used to police the unique constraint as a unique index must have the same list of column under duress. Index 4, to establish in a non-unique index or to remove the column id of the index. To index 5, you will need to make a non-unique index or remove the columns id and index t_type.

  (2) 3 index cannot be used to the unique constraint of police that it is a local index and is not partitioned column (t_type) in both the definition of index/constraint. If allowed, this would require Oracle having to visit each partition to ensure that any new value of t_key is truly unique, that would not scale. Include the t_type column in the constraint and the index to both t_type and t_key as of the columns (so move the id column 3rd position) and it would be successful.

  (Index 3) 8 fails for the same reason as in 1). It's a unique index with a different column from the constraint list. Remove the id column of the index or to make it a non-unique index and it will be successful.

  In summary, a unique index MUST have the same list of column than the constraint and a local index MUST have the partitioning columns in both the definition of index/constraint.

  See you soon

  Richard Foote

  http://richardfoote.WordPress.com/

• Unique key on the partitioned table range

  Hello
  
  We use a range of composite range-hash partitioned table
  
  Use index - try to do this have same tablespace to the local partitions but not liking it
  
  ALTER table RETAILER_TRANSACTION_COMP_POR
  Add primary key constraint RETAILER_TRANSACTION_COMP_PK (DWH_NUM)
  using index
  LOCAL
  
  
  ORA-14039: partitioning columns must be a subset of the columns in a unique index key
  
  Without local then fine but does not have same tablespace to walls and don't want to make this part of the partition key.
  
  Range Tbal partitioned - it's just a UK to avoid duplicates

  [oracle@localhost ~]$ oerr ora 14039
  14039, 00000, "partitioning columns must form a subset of key columns of a UNIQUE index"
  // *Cause:  User attempted to create a UNIQUE partitioned index whose
  //          partitioning columns do not form a subset of its key columns
  //          which is illegal
  // *Action: If the user, indeed, desired to create an index whose
  //          partitioning columns do not form a subset of its key columns,
  //          it must be created as non-UNIQUE; otherwise, correct the
  //          list of key and/or partitioning columns to ensure that the index'
  //          partitioning columns form a subset of its key columns
  

• 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.

• Change of primary key on the Table clears the other columns

  Preliminary info/Installation
  JDeveloper 11 g 11.1.1.6.0
  We have a table (object view or entity) that has 8 columns. The primary key is composed of 4 1 columns.
  The table is displayed in a page fragment.
  2 of the 4 non-primary key columns are LOV.
  All the 8 columns are needed.
  The table is editable including 2 of primary key columns.
  
  Question
  Assume that the table displays the 3 lines. If we change a rank 1 non-primary key column and a primary key in row 2 column, everything works well when we are committed to the database
  If, however, we first change a primary key column, then a primary key on a different line column, then the column/row primary key that changed us first, gets annihilated and the other columns LOV on this same line. The 2 columns that are not LOV keep data as it should. We then get a validation error because the required data are not present. All this happens before we try all commit to the database. If debug us and look the iterator, it has the old data in this document, before and after any performance on the binding.
  If we look at and update the data via the App Module, everything works well. We have tried to update the view, etc. through valueChangeListener also with no luck.

  If you change the primary key value, it should not be the primary key.

  This is true in the design of database relational regardless of how access you the data. In addition, EO don't like if you change the primary key value.

  Have you considered adding a surrogate key (use a sequence) and make your PK course a unique key?

  John

• How to set a validation rule on a unique key formed by more than columns

  Hi all
  I use Jdeveloper 11.1.1.2
  I have a table with a column 3: col1, col2, col3. On that note, I have defined a unique key formed by col2 and col3.
  How can I define a validation rule on this key?
  In the entity object, I can't find anything useful, I see only attributes, but not the single key just defined (in the source of the entity object I have the code on the unique key).
  
  Thank you
  
  Andrea
  
  Published by: Andrea9 on February 11, 2010 03:46

  Yes, that's correct.

  You will realize that the approach set out in the Manual:

  (1) has a possibility to create duplicates (that is, you still need the unique key in the DB).

  (2) is slower (requires intermediate to read all values db at the intermediate level)

  You could, as Marie-Ange suggested to write the code as described in the post to blog as well - however, it has the same drawbacks.

  If you really need ID dups before validation, you will have to live with the disadvantages of the approach defined.

  Best,

  John

• How to delete records from a table that has a composite unique key duplicate

  Hello
  I get the customer data from various sources in the staging of the table where I insert in the database table where the combination of two columns is considered as a unique key. But there is a possibility of duplicates. How to find duplicates in a SQL or pl/sql
  
  Thank you
  Manoi.

  Kassa,

  You can see the duplicates by using the following query...

  sql> select * from temp_rajesh;
  
        COL1       COL2 MESSAGE
  ---------- ---------- ------------------
         100        200 message
         100        200 message2
         300        400 message3
         400        500 message 4
  
  sql> select col1, col2, count(*)
    2     from temp_rajesh
    3       group by col1, col2
    4         having count(*) > 1;
  
        COL1       COL2   COUNT(*)
  ---------- ---------- ----------
         100        200          2
  

  -If in the case of duplicate records, you should see only the duplicates (according to some timestamp etc., you can use the functinon row_number analytic..)

    1  select col1, col2 from (
    2  select col1, col2,
    3         row_number() over (partition by col1, col2
    4                            order by message) rn
    5    from temp_rajesh)
    6*   where rn > 1
  sql> /
  
        COL1       COL2
  ---------- ----------
         100        200
  

  In the above example, I use message to order, you can replace it with activity_timestamp or the insertd_date according to your logic... when there are two records... one that you choose to duplicate.

  Thank you
  Rajesh.

  Published by: Rajesh Chamarthi on November 20, 2009 12:05 AM (added for example)

• Select the table column group and generate a sequence number

  I have to select data from a table column group and generate a sequence for every reset of the sequence from 1 to leave.
  
  For example:
  
  Data:
  Col1 Col2 Col3 Col4
  A NA KA-2009-08-13
  B NA KA-2009-08-13
  C NA KA-2009-08-13
  A NA KA-2009-08-13
  B NA KA-2009-08-13
  A NA KA-2009-08-13
  
  Expected results of the Select statement:
  Col1 Col2 Col3 Col4 Seq_No
  A NA KA-2009-08-13 1
  A NA KA-2009-08-13 2
  A NA KA-2009-08-13 3
  B NA KA-2009-08-13 1
  B NA KA-2009-08-13 2
  C NA KA-2009-08-13 1
  
  How can it be possible with a SELECT statement? Is it possible to assign the following numbers for a group of columns and put it back when it changes? In the above example, all columns are the key to generate the seq number
  
  I know that this can be done using procedures stored and that is how I do it now by introducing a temporary table.
  
  Can someone help me with this? Please let me know if the question is too vague to understand!
  
  Thank you
  Nachi

  Use the row_number() analytics.

  Ravi Kumar

• How can I get a name of table 1, column A, if column B is a negative number and insert the names of table 2?

  How can I get a name of table 1, column A, if column B is a negative number and insert the names of table 2?

  What is the formula?

  

  You can do this with a column of "index" in table 1, as this assistance:

  

  The formula in C2, filled to the bottom:

  IF (B =<>

  That increments a counter each time that it finds a negative number in column B.

  In the second table, you can retrieve a list of negative values in this way:

  

  The formula in A2, filled to the bottom:

  = INDEX (array 1::A, CORRESPONDENCE (LINE (−1, Table 1::C), 0))

  It takes the line number, the formula is activated, subtracts 1 to the header line and look up the result in the column of table 1 C.  If it finds a match, it feeds the line number to the INDEX page with retrieves the value of the column of table 1A.

  To hide the red triangles of signage wrap the IFERROR formula, like this:

  = SIERREUR (INDEX (table 1::A, CORRESPONDENCE (LINE (−1, Table 1::C), 0)),"")

  Of course, you can also simply filter on column B without the need to set up a column from another table or index.

  

  SG

• How can I insert a number to a specific index (row and column) to a table

  I had the most with function 'insert into array' problem because of its counter-intuitiveness. I want to insert a number I got inside a loop IN a table. The ROW and COLUMN of this table I want enter the number is specified by the number of loops of two loops FOR. It did not work.

  So, I have isolated and tested this function further. Frankly, I initialized a table 2D with ZEROS and plugged into the "insert into array" function (on top of entry). I then put the number '1' for the index (line) and the number "2" for the index (column) and then put the entry number "6" for the "new item/sub-table. Then, I hung a picture of 2-D (indicator) output to the output of the function "insert into array. When I did all that, it means I want to just put the number '6' in line '1' and the column '2'... This isn't letting me do it.

  How can I do this SIMPLE?

  Hi Darrell h...,

  Looks like you can use the function "autoindexing. Take your value and connect it to your loop, it will be a default autoindexing. Right-click on the last tunnel of output and select Create indicator, the result is your table.

  It will be useful.

  Mike

• Can I use several nulls in a unique key column

  Happy Pongal (SANKRANTHI) friends hi... Can you please help me in this regard...
  
  Can I use several nulls in a unique key column?

  Yes you can have