I have created a table (test_table), that has two columns (test_IP, test_STATUS). The table can have any number of IPs, however, only one IP with the status "Active" can be allowed. Any number of "Inactive" status' may be allowed. For reference (Active = 1, Inactive = 2)
For example:
test_IP test_STATUS
==============================
1.2.3.4 1
1.2.3.5 2
1.2.3.6 2
1.2.3.7 2
1.2.3.8 1 -- this should now fail (as there are multiple values containing 1 (Active))
Is it possible to have a unique contraint on a specific value? If so can someone please assist me on how I can achieve this? Thanks in advance!
Use a unique function based index, that considers only the active rows and resets the non active key to NULL
Example
select * from tab order by 1,2;
TEST_IP TEST_STATUS
------- -----------
1.1.1.1 1
1.1.1.1 2
1.1.1.1 2
1.1.1.1 2
1.1.1.2 1
create unique index tab_ixd on tab (case when test_STATUS = 1 then test_IP end);
insert into tab (test_IP,test_STATUS) values ('1.1.1.1', 2);
1 row inserted.
insert into tab (test_IP,test_STATUS) values ('1.1.1.1', 1);
ORA-00001: unique constraint (ZZZZ.TAB_IXD) violated
The above solution works if you allow one active row per IP address. If you need a constraint for only one active row per the whole table, use:
create unique index tab_ixd on tab (case when test_STATUS = 1 then test_STATUS end);
I would add virtual invisible column is_active:
alter table ip_list
add is_active varchar2(1)
invisible
generated always as
(case when test_STATUS=1 then 'y' end) virtual;
alter table ip_list add constraint uq_active_ip unique (is_active);
Since it's invisible, it will not affect existing queries. You can get it only if you specify is_active in your query.
Full example:
SQL> create table ip_list(test_IP,test_STATUS)
2 as
3 select '1.2.3.4', 1 from dual union all
4 select '1.2.3.5', 2 from dual union all
5 select '1.2.3.6', 2 from dual union all
6 select '1.2.3.7', 2 from dual ;
Table created.
SQL> alter table ip_list add is_active varchar2(1) invisible generated always as (case when test_STATUS=1 then 'y' end) virtual;
Table altered.
SQL> alter table ip_list add constraint uq_active_ip unique (is_active);
Table altered.
SQL> insert into ip_list(test_ip, test_status) values('1.2.3.8',1);
insert into ip_list(test_ip, test_status) values('1.2.3.8',1)
*
ERROR at line 1:
ORA-00001: unique constraint (XTENDER.UQ_ACTIVE_IP) violated
-- note that * does not return this new column:
SQL> select * from ip_list;
TEST_IP TEST_STATUS
------- -----------
1.2.3.4 1
1.2.3.5 2
1.2.3.6 2
1.2.3.7 2
-- but you can use it to filter active rows:
SQL> select * from ip_list where is_active='y';
TEST_IP TEST_STATUS
------- -----------
1.2.3.4 1
1 row selected.
If the test_status column can contain null value and the 1 value means that the ip is active, and instead of 2 you use null for the inactivity, then the unique constraint will work.
But I think it is not a really elegant solution.
Related
I am trying to Create a list partition Based on the column "REFRESH_FLAG_Y" which has only Y and N as its Values, Below is the Alter Table used to Create the partition
ALTER TABLE "EDW"."LABOR_SCHEDULE_DAY_F" MODIFY
PARTITION BY LIST ("REFRESH_FLAG")
(PARTITION "REFRESH_FLAG_Y" VALUES ('Y') ,
PARTITION "REFRESH_FLAG_N" VALUES ('N')) ;
COMMIT;
But Whenever I execute the code I get an Error message
ERROR at line 1:
ORA-14400: inserted partition key does not map to any partition
You did tag the question with Oracle 11g tag; do you really use it?
This is a 12c example; it works if everything is OK:
SQL> create table labor_schedule_day_f as
2 select 1 id, 'Y' refresh_flag from dual union all
3 select 2 id, 'N' refresh_flag from dual;
Table created.
SQL> alter table labor_schedule_Day_f modify
2 partition by list (refresh_flag)
3 (partition refresh_flag_y values ('Y'),
4 partition refresh_flag_n values ('N')
5 );
Table altered.
Error you reported means this:
SQL> drop table labor_schedule_day_f;
Table dropped.
SQL> create table labor_schedule_day_f as
2 select 1 id, 'Y' refresh_flag from dual union all
3 select 2 id, 'N' refresh_flag from dual;
Table created.
Insert a row whose REFRESH_FLAG isn't Y nor N (so it violates the rule you specified):
SQL> insert into labor_schedule_day_f values (3, 'X');
1 row created.
Using the same ALTER TABLE statement as previously:
SQL> alter table labor_schedule_Day_f modify
2 partition by list (refresh_flag)
3 (partition refresh_flag_y values ('Y'),
4 partition refresh_flag_n values ('N')
5 );
alter table labor_schedule_Day_f modify
*
ERROR at line 1:
ORA-14400: inserted partition key does not map to any partition
SQL>
See? Error you got, which means that
which has only Y and N as its Values
isn't true.
P.S. You'd get the same result even if refresh_flag was NULL for some rows.
as my title, I want to change my identity column by sequence to GENERATED ALWAYS.
For ex, I have a table like this:
CREATE SEQUENCE DPT.Deposit_SEQ
START WITH 1
INCREMENT BY 10
NOCACHE
NOCYCLE;
CREATE TABLE DPT.TEST(
Id NUMBER(10)DEFAULT DPT.Deposit_SEQ.nextval NOT NULL
,Code VARCHAR2(20),
CONSTRAINT PK_TEST PRIMARY KEY (ID)
);
Insert into DPT.TEST (ID, CODE) values (1,'ABC');
COMMIT;
Now, I want to change from sequence to GENERATED ALWAYS like this:
Id NUMBER(10) GENERATED ALWAYS AS IDENTITY START WITH 6
INCREMENT BY 10
NOCACHE
NOCYCLE;
I tried by create one more column and drop old column but failed. How can I do that?
Thanks!
"But failed" is not an Oracle error and is difficult to debug.
Anyway, it works for me:
Create table and a sequence, insert some rows:
SQL> CREATE SEQUENCE Deposit_SEQ START WITH 1 INCREMENT BY 10 NOCACHE NOCYCLE;
Sequence created.
SQL> CREATE TABLE TEST
2 (
3 Id NUMBER (10) DEFAULT Deposit_SEQ.NEXTVAL NOT NULL,
4 Code VARCHAR2 (20),
5 CONSTRAINT PK_TEST PRIMARY KEY (ID)
6 );
Table created.
SQL>
SQL> INSERT INTO TEST (ID, CODE)
2 VALUES (1, 'ABC');
1 row created.
SQL> INSERT INTO TEST (ID, CODE)
2 VALUES (3, 'DEF');
1 row created.
SQL> SELECT * FROM test;
ID CODE
---------- --------------------
1 ABC
3 DEF
Drop current primary key column (ID) and add a new, identity column:
SQL> ALTER TABLE test
2 DROP COLUMN id;
Table altered.
SQL> ALTER TABLE test
2 ADD id NUMBER GENERATED ALWAYS AS IDENTITY START WITH 6;
Table altered.
SQL> SELECT * FROM test;
CODE ID
-------------------- ----------
ABC 6
DEF 7
SQL> ALTER TABLE test ADD CONSTRAINT pk_test PRIMARY KEY (id);
Table altered.
SQL>
As you can see, no problem.
I have 2 tables like below,
Master_Data_1
Id Name
1 AAA
2 BBB
3 DDD
4 CCC
Master_Data_2
Id Name Upt_Flg
1 DDD False
2 EEE False
3 FFF False
both tables have same ID but different Name, and ID field is neither auto incremented nor sequence. But ID is a not null primary key column which will be generated based on MAX ID logic.
In this case i am trying to merge Master_Data_1 table with Master_Data_2 table using oracle merge statement.
So i am having issue in WHEN NOT MATCHED THEN case, i am trying to insert not matched records in to Master_data_2 table from master_data_1 table.
In this scenario ID in Master_Data_2 table will not be auto incremented, and also i cannot use the source table ID here because it will lead to unique constraint exception.
Note : I don't want to alter a table to make ID auto increment or adding sequence for ID.
Expected Output in Master_Data_2 table using merge query:
Id Name Upt_Flg
1 DDD TRUE
2 EEE False
3 FFF False
4 AAA False
5 BBB False
6 CCC False
is there any other way to achieve this?
I guess ROW_NUMBER analytic function might help you here.
MERGE INTO Master_Data_2 md2
USING (SELECT (SELECT MAX(id) FROM Master_Data_2) + ROW_NUMBER() OVER(ORDER BY id) new_id
,name
FROM Master_Data_1
) md1
ON (md2.name = md1.name)
WHEN MATCHED THEN UPDATE
SET Upt_flg = 'TRUE'
WHEN NOT MATCHED THEN
INSERT (md2.id, md2.name)
VALUES (Md1.new_id, md1.name);
Here is the fiddle
You can simply achieve it using INSERT and MINUS operator as following:
insert into master_data_2
select
(select max(id) from master_data_2) + row_number() over (order by 1),
name
from
(select name from master_data_1
minus
select name from master_data_2)
db<>fiddle demo
Cheers!!
The situation is that, when I import a file into the database, one of the first thing I usually do is to assign an unique ID for each record.
I normally do below in TSQL
ALTER TABLE MyTable
ADD ID INT IDENTITY(1,1)
I am wondering if there is something similar in PL SQL?
All my search result come back with multiple steps.
Then I'd like to know what PL SQL programmer typically do to ID records after importing a file. Do they do that?
The main purpose for me to ID these records is to trace it back after manipulation/copying.
Again, I understand there is solution there, my further question is whether PL SQL programmer actually do that, or there is other alternative which making this step not necessary in PL SQL?
OK then, as you're on Oracle 11g, there's no identity column there so - back to multiple steps. Here's an example:
I'm creating a table that simulates your imported table:
SQL> create table tab_import as
2 select ename, job, sal
3 from emp
4 where deptno = 10;
Table created.
Add the ID column:
SQL> alter table tab_import add id number;
Table altered.
Create a sequence which will be used to populate the ID column:
SQL> create sequence seq_imp;
Sequence created.
Update current rows:
SQL> update tab_import set
2 id = seq_imp.nextval;
3 rows updated.
Create a trigger which will take care about future inserts (if any):
SQL> create or replace trigger trg_bi_imp
2 before insert on tab_import
3 for each row
4 begin
5 :new.id := seq_imp.nextval;
6 end;
7 /
Trigger created.
Check what's in the table at the moment:
SQL> select * from tab_import;
ENAME JOB SAL ID
---------- --------- ---------- ----------
CLARK MANAGER 2450 1
KING PRESIDENT 5000 2
MILLER CLERK 1300 3
Let's import some more rows:
SQL> insert into tab_import (ename, job, sal)
2 select ename, job, sal
3 from emp
4 where deptno = 20;
3 rows created.
The trigger had silently populated the ID column:
SQL> select * From tab_import;
ENAME JOB SAL ID
---------- --------- ---------- ----------
CLARK MANAGER 2450 1
KING PRESIDENT 5000 2
MILLER CLERK 1300 3
SMITH CLERK 800 4
JONES MANAGER 2975 5
FORD ANALYST 3000 6
6 rows selected.
SQL>
Shortly: you need to
alter table and add the ID column
create a sequence
create a trigger
The end.
The answer given by #Littlefoot would be my recommendation too - but still I thought I could mention the following variant which will work only if you do not intend to add more rows to the table later.
ALTER TABLE MyTable add id number(38,0);
update MyTable set id = rownum;
commit;
My test:
SQL> create table tst as select * from all_tables;
Table created.
SQL> alter table tst add id number(38,0);
Table altered.
SQL> update tst set id = rownum;
3815 rows updated.
SQL> alter table tst add constraint tstPk primary key (id);
Table altered.
SQL>
SQL> select id from tst where id < 15;
ID
----------
1
2
3
4
5
6
7
8
9
10
11
ID
----------
12
13
14
14 rows selected.
But as mentioned initially,- this only fixes numbering for the rows you have at the time of the update - your'e not going to get new id values for new rows anytime later - if you need that, go for the sequence solution.
You can add an id column to a table with a single statement (Oracle 11g, see dbfiddle):
alter table test_
add id raw( 16 ) default sys_guid() ;
Example:
-- create a table without an id column
create table test_ ( str )
as
select dbms_random.string( 'x', 16 )
from dual
connect by level <= 10 ;
select * from test_ ;
STR
ULWL9EXFG6CIO72Z
QOM0W1R9IJ2ZD3DW
YQWAP4HZNQ57C2UH
EETF2AXD4ZKNIBBF
W9SECJYDER793MQW
alter table test_
add id raw( 16 ) default sys_guid() ;
select * from test_ ;
STR ID
ULWL9EXFG6CIO72Z 0x782C6EBCAE2D7B9FE050A00A02005D65
QOM0W1R9IJ2ZD3DW 0x782C6EBCAE2E7B9FE050A00A02005D65
YQWAP4HZNQ57C2UH 0x782C6EBCAE2F7B9FE050A00A02005D65
EETF2AXD4ZKNIBBF 0x782C6EBCAE307B9FE050A00A02005D65
W9SECJYDER793MQW 0x782C6EBCAE317B9FE050A00A02005D65
Testing
-- Are the id values unique and not null? Yes.
alter table test_
add constraint pkey_test_ primary key ( id ) ;
-- When we insert more rows, will the id be generated? Yes.
begin
for i in 1 .. 100
loop
insert into test_ (str) values ( 'str' || to_char( i ) ) ;
end loop ;
end ;
/
select * from test_ order by id desc ;
-- last 10 rows of the result
STR ID
str100 0x782C806E16A5E998E050A00A02005D81
str99 0x782C806E16A4E998E050A00A02005D81
str98 0x782C806E16A3E998E050A00A02005D81
str97 0x782C806E16A2E998E050A00A02005D81
str96 0x782C806E16A1E998E050A00A02005D81
str95 0x782C806E16A0E998E050A00A02005D81
str94 0x782C806E169FE998E050A00A02005D81
str93 0x782C806E169EE998E050A00A02005D81
str92 0x782C806E169DE998E050A00A02005D81
str91 0x782C806E169CE998E050A00A02005D81
Regarding your other questions:
{1} Then I'd like to know what PL SQL programmer typically do to ID records after importing a file. Do they do that? The main purpose for me to ID these records is to trace it back after manipulation/copying.
-> As you know, the purpose of an id is: to identify a row. We don't "do anything to IDs". Thus, your usage of IDs seems legit.
{2} Again, I understand there is solution there, my further question is whether PL SQL programmer actually do that, or there is other alternative which making this step not necessary in PL SQL?
-> Not quite sure what you are asking here. Although there is a ROWID() pseudocolumn (see documentation), we should not use it to identify rows.
"You should not use ROWID as the primary key of a table. If you delete
and reinsert a row with the Import and Export utilities, for example,
then its rowid may change. If you delete a row, then Oracle may
reassign its rowid to a new row inserted later."
I need to create a sequence and a trigger to auto-increment the primary key on a table but I have no idea on how to do it.
Create the table and the sequence
SQL> create table staff (
2 emp_id number primary key,
3 staff_name varchar2(100)
4 );
Table created.
SQL> create sequence emp_id_seq;
Sequence created.
Now, you can create a trigger that uses the sequence to populate the primary key
SQL> create trigger trg_emp_id
2 before insert on staff
3 for each row
4 begin
5 select emp_id_seq.nextval
6 into :new.emp_id
7 from dual;
8 end;
9 /
Trigger created.
Now, when you insert data, you woon't need to specify the EMP_ID column-- it will automatically be populated by the trigger
SQL> insert into staff( staff_name ) values ('Justin');
1 row created.
SQL> select * from staff;
EMP_ID STAFF_NAME
---------- --------------------
1 Justin
Read this, Beautiful article.
how sequence [auto increment in oracle]
syntax
Create sequence sequence_name
start with value
increment by value
minvalue value
maxvalue value;
example
SQL> create table emp (
emp_id number(10),
fname varchar2(25),
lname varchar2(25),
constraint pk_emp_id PRIMARY KEY(emp_id)
);
SQL> Create sequence emp_sequence
start with 1
increment by 1
minvalue 1
maxvalue 10000;
SQL> insert into emp (emp_id,fname,lname) values(emp_sequence.nextval,'Darvin','Johnson');
SQL> insert into emp (emp_id,fname,lname) values(emp_sequence.nextval,'Mig','Andrews');
SQL> insert into emp (emp_id,fname,lname) values(emp_sequence.nextval,'Alex','Martin');
SQL> insert into emp (emp_id,fname,lname) values(emp_sequence.nextval,'Jon','paul');
SQL> insert into emp (emp_id,fname,lname) values(emp_sequence.nextval,'Yatin','Bones');
in emp_sequence.nextval where emp_sequence is the name of sequence we created above and nextval is a function that is used to assign the next number from emp_sequence to emp_id column in emp table.
SQL> select * from emp;
EMP_ID FNAME LNAME
---------- ------------------------- -------------------------
1 Darvin Johnson
2 Mig Andrews
3 Alex Martin
4 Jon paul
5 Yatin Bones
Try this:
create sequence seq_EmpID start with 1 increment by 1
insert into Emp_Table values(seq_EmpID.nextval,'Ram')
I am not sure which version of Oracle you are using, but the following will work in 19c:
create table staff (
emp_id NUMBER GENERATED BY DEFAULT ON NULL AS IDENTITY PRIMARY KEY,
staff_name varchar2(100)
);
https://docs.oracle.com/en/database/other-databases/nosql-database/19.3/java-driver-table/creating-tables-identity-column.html
The command above creates a system sequence that is automatically employed to populate the key value. you cannot drop the sequence created as it is a system sequence, but because of the dependency on the column when the table is dropped and the recycle bin purged it is removed.
Very good question!!
Probably sequence can be used in this way - also, I am not sure if there really is a difference :
CREATE SEQUENCE emp_id_seq MINVALUE 1 START WITH 1 INCREMENT BY 1 CACHE 10;
First creating the table :
sql-> create table item(id int primary key, name varchar(25),qty int, price int);
Now we want to make auto increment sequence to the first column i.e. id
sql-> CREATE SEQUENCE id MINVALUE 1 START WITH 1 CACHE 10; //system saves the last 10 items in temp memory
This will create auto increment.
Now we are inserting data:
sql-> insert into item VALUES(id.nextval,'ddcd',2,4);
sql-> insert into item VALUES(id.nextval,'ddcd',676,4);
Finally Displaying the table :
SQL> select * from item;
ID NAME QTY PRICE
1 ddcd 2 4
2 ddcd 676 4
If you use a sequence for several tables, because the value of the sequence is inconsistent example:
we have two tables emp and depeartement:
If I use the sequence on emp I would have: ID_dept = 6 because the 5 is already used in the other table.
example :
SQL> insert into emp values(masequence.nextval,'aaa');
1 ligne crÚÚe.
SQL> insert into departement values(masequence.nextval,'aaa');
1 ligne crÚÚe.
SQL> select * from emp;
ID_EMP NOM_EMP
---------- -------------------------
5 aaa
SQL> select * from departement;
ID_DEPT NOM_DEPT
---------- ----------
6 aaa
SQL>