Object (Table, View ...) Status Metadata in Postgres - oracle

Is it possible to query object (object being table, view, etc.) status in Postgres? In Oracle an equivalent query would be:
SELECT owner,
object_name,
status
FROM all_objects
WHERE object_type = 'VIEW'
(returns VALID/INVALID in status column)
Please let me know. I've googled for this already, but have not found much.
Michael

https://stackoverflow.com/a/39120069/5315974
Postgres does not let you break the view (RULE), eg:
t=# create table so183 (i int);
CREATE TABLE
t=# create view v183 as select i from so183;
CREATE VIEW
t=# alter table so183 alter COLUMN i type text using i::text;
ERROR: cannot alter type of a column used by a view or rule
DETAIL: rule _RETURN on view v183 depends on column "i"

Related

Unable to create table through another table in oracle SQL developer

I have been trying to create a new table by using below query :
"Create table d1_details_test2
as
select * from d1_details"
this above query gives me an error :
actually "d1_details" table has one column which has "Long" datatype and i cannot change it.
so i want to know the any other way to create the table.
Thanks
The long data type is subject to many restrictions. Create table as select is one of these.
You can get around it by applying to_lob in the select, which converts it to a clob:
create table views as
select view_name, text from user_views;
ORA-00997: illegal use of LONG datatype
create table views as
select view_name, to_lob ( text ) lob
from user_views;
desc views
Name Null? Type
VIEW_NAME VARCHAR2(128)
LOB CLOB

Oracle Datatype Modifier

I need to be able to reconstruct a table column by using the column data in DBA_TAB_COLUMNS, and so to develop this I need to understand what each column refers to. I'm looking to understand what DATA_TYPE_MOD is -- the documentation (http://docs.oracle.com/cd/B19306_01/server.102/b14237/statviews_2094.htm#I1020277) says it is a data type modifier, but I can't seem to find any columns with this field populated or any way to populate this field with a dummy column. Anyone familiar with this field?
Data_type_mod column of the [all][dba][user]_tab_columns data dictionary view gets populated when a column of a table is declared as a reference to an object type using REF datatype(contains object identifier(OID) of an object it points to).
create type obj as object(
item number
) ;
create table tb_1(
col ref obj
)
select t.table_name
, t.column_name
, t.data_type_mod
from user_tab_columns t
where t.table_name = 'TB_1'
Result:
table_name column_name data_type_mod
-----------------------------------------
TB_1 COL REF
Oracle has a PL/SQL package that can be used to generate the DDL for creating a table. You would probably be better off using this.
See GET_DDL on http://docs.oracle.com/cd/B19306_01/appdev.102/b14258/d_metada.htm#i1019414
And see also:
How to get Oracle create table statement in SQL*Plus

How to compare two Oracle schemas to get delta changes by Altering the table not to drop and recreate it

I've already tried out a tool named TOYS. I found it free but unfortunately it didn't work.
Then, I tried "RED-Gate Schema Compare for Oracle" but it uses the technique to drop and recreate the table mean while I need to just alter the table with the newly added/dropped columns.
Any help is highly appreciated
Thanks
Starting from Oracle 11g you could use dbms_metadata_diff package and specifically compare_alter() function to compare metadata of two schema objects:
Schema #1 HR
create table tb_test(
col number
)
Schema #2 HR2
create table tb_test(
col_1 number
)
select dbms_metadata_diff.compare_alter( 'TABLE' -- schema object type
, 'TB_TEST' -- object name
, 'TB_TEST' -- object name
, 'HR' -- by default current schema
, 'HR2'
) as res
from dual;
Result:
RES
-------------------------------------------------
ALTER TABLE "HR"."TB_TEST" ADD ("COL_1" NUMBER);
ALTER TABLE "HR"."TB_TEST" DROP ("COL");

How to set default value for column of new created table from select statement in 11g

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;

Oracle: Is there a way to get the column data types for a view?

For a table in oracle, I can query "all_tab_columns" and get table column information, like the data type, precision, whether or not the column is nullable.
In SQL Developer or TOAD, you can click on a view in the GUI and it will spit out a list of the columns that the view returns and the same set of data (data type, precision, nullable, etc).
So my question is, is there a way to query this column definition for a view, the way you can for a table? How do the GUI tools do it?
You can use user_tab_columns (or all_tab_columns and dba_tab_columns respectively) regardless if table_name refers to a view or a table.
View columns appear in all_tab_columns, so you can query them just as you can tables.
Just simply write this query:
SQL> desc TABLE/VIEW NAME;
For example if the table/view name is "department" Then just write:
SQL> desc department;
This will give the list of all fields, it's type and default Null info of the table or view.
you can use the ANSI catalog views, should work for most RDBMs
select *
from information_schema.columns c
join information_schema.tables t on c.table_name = t.table_name
where table_type = 'view'

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