I have two Oracle questions.
How can I set the primary key of a table when the table is made up of an object type? e.g.
CREATE TABLE object_names OF object_type
I have created a Varray type,
CREATE TYPE MULTI_TAG AS VARRAY(10) OF VARCHAR(10);
but when I try to do
SELECT p.tags.count FROM pg_photos p;
I get an invalid identifier error on the "count" part. p.tags is a MULTI_TAG, how can I get the number of elements in the MULTI_TAG?
First of all I wouldn't recommend storing data in Object tables. Objects are a great programmatic tool but querying Object tables leads to complicated SQL. I would advise storing your data in a standard relationnal model and using the objects in your procedures.
Now to answer your questions:
A primary key should be immutable, so most of the time an Object type is inappropriate for a primary key. You should define a surrogate key to reference your object.
You will have to convert the varray into a table to be able to query it from SQL
For example:
SQL> CREATE TYPE MULTI_TAG AS VARRAY(10) OF VARCHAR(10);
2 /
Type created
SQL> CREATE TABLE pg_photos (ID number, tags multi_tag);
Table created
SQL> INSERT INTO pg_photos VALUES (1, multi_tag('a','b','c'));
1 row inserted
SQL> INSERT INTO pg_photos VALUES (2, multi_tag('e','f','g'));
1 row inserted
SQL> SELECT p.id, COUNT(*)
2 FROM pg_photos p
3 CROSS JOIN TABLE(p.tags)
4 GROUP BY p.id;
ID COUNT(*)
---------- ----------
1 3
2 3
1)
A primary key is a constraint, to add constrains on object tables check this link:
http://download-west.oracle.com/docs/cd/B28359_01/appdev.111/b28371/adobjdes.htm#i452285
2)
The COUNT method can't be used in a SQL statement:
REF LINK IN COMMENTS
So in my case I had to do
SELECT p.pid AS pid, count(*) AS num_tags FROM pg_photos p, TABLE(p.tags) t2 GROUP BY p.pid;
Related
Suppose if the table name is ABC_XYZ_123. I want to extract the integer values after _.
The output should be integer values after _.
In the above case, the output should be 123.
I have used the below sql query.
select from table_name like 'XXX_%';
But I am not getting required output. Can anyone help me with this query.
Thanks
Using REGEXP_SUBSTR with a capture group we can try:
SELECT REGEXP_SUBSTR(name, '_(\d+)$', 1, 1, NULL, 1)
FROM yourTable;
The question is somewhat unclear:
it looks as if you're looking for table names that contain number at the end, while
query you posted suggests that you're trying to select those numbers from one of table's columns
I'll stick to
Suppose if the table name is ABC_XYZ_123
If that's so, it is the data dictionary you'll query. USER_TABLES contains that information.
Let's create that table:
SQL> create table abc_xyz_123 (id number);
Table created.
Query selects numbers at the end of table names, for all my tables that end with numbers.
SQL> select table_name,
2 regexp_substr(table_name, '\d+$') result
3 from user_tables
4 where regexp_like(table_name, '\d+$');
TABLE_NAME RESULT
-------------------- ----------
TABLE1 1
TABLE2 2
restore_point-001 001
ABC_XYZ_123 123 --> here's your table
SQL>
Apparently, I have a few of them.
I am pulling some records in table A from X table.
Now, I want to select records which are not available in table A but available in table B. But at the same time, I don't want to select records available in both tables.
Moreover,if a column in table A is null but the same column in the record in table B has value, I want to take that too.
Is it possible to do something like this in one statement ?
This is a simple set based operation. Relational databases are very good in that:
CREATE TABLE a (id NUMBER);
CREATE TABLE b (id NUMBER);
INSERT INTO a VALUES (1);
INSERT INTO a VALUES (3);
INSERT INTO b VALUES (2);
INSERT INTO b VALUES (3);
SELECT id FROM b
MINUS
SELECT id FROM a;
ID
2
How to increment the value of the unique constraint column value in ORACLE, in the select statement.
For example, in a table 'BILLING_TABLE' - column BLNG_Sk is the unique key (Autoincremented).
So while inserting a new record into the BILLING_TABLE, for the column BLNG_SK we need to give the value (Which is the increment by 1 from the present max value.)
For example, if BLNG_SK max value is 12321.
new record should be 12322.
how to achieve this in Oracle?
Oracle has a SEQUENCE object which provides the functionality you require.
You create one using the CREATE SEQUENCE SQL statement.
The Oracle documentation provides all the required information and the documentation is available via Oracle's Web site.
Assuming you are on Oracle 12.1 or later, define it as an identity column and do not pass any value when inserting:
create table testtable
( test_id number generated always as identity
constraint testtable_pk primary key
, othercol varchar2(10) );
insert into testtable (othercol) values ('Demo');
select * from testtable;
TEST_ID OTHERCOL
---------- ----------
1 Demo
insert into testtable (othercol) values ('Demo #2');
select * from testtable;
TEST_ID OTHERCOL
---------- ----------
1 Demo
2 Demo #2
Try creating a sequence and a trigger. This is the case when you provide the value manually.
CREATE SEQUENCE dept_seq START WITH 12322;
Trigger definition:
CREATE OR REPLACE TRIGGER dept_bir
BEFORE INSERT ON BILLING_TABLE
FOR EACH ROW
BEGIN
SELECT dept_seq.NEXTVAL
INTO :new.id
FROM dual;
END;
/
I create a table in Oracle 11g with the default value for one of the columns. Syntax is:
create table xyz(emp number,ename varchar2(100),salary number default 0);
This created successfully. For some reasons I need to create another table with same old table structure and data. So I created a new table with name abc as
create table abc as select * from xyz.
Here "abc" created successfully with same structure and data as old table xyz. But for the column "salary" in old table "xyz" default value was set to "0". But in the newly created table "abc" the default value is not set.
This is all in Oracle 11g. Please tell me the reason why the default value was not set and how we can set this using select statement.
You can specify the constraints and defaults in a CREATE TABLE AS SELECT, but the syntax is as follows
create table t1 (id number default 1 not null);
insert into t1 (id) values (2);
create table t2 (id default 1 not null)
as select * from t1;
That is, it won't inherit the constraints from the source table/select. Only the data type (length/precision/scale) is determined by the select.
The reason is that CTAS (Create table as select) does not copy any metadata from the source to the target table, namely
no primary key
no foreign keys
no grants
no indexes
...
To achieve what you want, I'd either
use dbms_metadata.get_ddl to get the complete table structure, replace the table name with the new name, execute this statement, and do an INSERT afterward to copy the data
or keep using CTAS, extract the not null constraints for the source table from user_constraints and add them to the target table afterwards
You will need to alter table abc modify (salary default 0);
new table inherits only "not null" constraint and no other constraint.
Thus you can alter the table after creating it with "create table as" command
or you can define all constraint that you need by following the
create table t1 (id number default 1 not null);
insert into t1 (id) values (2);
create table t2 as select * from t1;
This will create table t2 with not null constraint.
But for some other constraint except "not null" you should use the following syntax
create table t1 (id number default 1 unique);
insert into t1 (id) values (2);
create table t2 (id default 1 unique)
as select * from t1;
I have run into an issue when creating a object type in Oracle 10g that inherits from a supertype. We currently have many object types that inherit from this supertype and recently the compiler started throwing the following errors
ORA-30745: error occured while trying to add column "SYS_NC_ROWINFO$" in table "DATA_CACHE.CACHE_ENTRIES"
ORA-01792: maximum number of columns in a table or view is 1000
Is there a cap on the number of subtypes you can generate that inherit from a supertype?
When you create tables with columns based on user-defined types, Oracle creates additional "secret" columns for you under the covers. For example:
SQL> create type emp_data_t as object (empno number, ename varchar2(30));
2 /
Type created.
SQL> create table emp_data_table (id int, emp_data emp_data_t);
Table created.
This table appears to have 2 columns:
SQL> desc emp_data_table
Name Null? Type
-------------------------- -------- ------------------------
ID NUMBER(38)
EMP_DATA EMP_DATA_T
... but it really has four:
SQL> select name
2 from sys.col$
3 where obj# = (select object_id
4 from user_objects
5 where object_name='EMP_DATA_TABLE');
NAME
------------------------------
ID
EMP_DATA
SYS_NC00003$
SYS_NC00004$
As you have seen, Oracle has a limit of 1000 columns per table. This limit will include any of these hidden columns derived from types and supertypes. It looks like your table has exceeded this limit.
use command:
PURGE RECYCLEBIN;