I'm using Oracle and I have a strange thing.
I dropped a table using :
drop table t_my_table, and committed.
But when I launch select * from t_my_table, it shows the data, as if the table is not dropped.
I tried disconnecting and reconnecting, it stills shows the data when I select.
And when I once again try with :
drop table t_my_table, it tells me that this table does not exist.
But if I run select again, the data is always there.
How is this possible ?
Thank you.
You mean this case?
create view t_my_table as
select 'I''m here' as txt from dual;
drop table t_my_table;
ORA-00942: table or view does not exist
But
select * from t_my_table;
TXT
--------
I'm here
solution of the most probably cause
select OBJECT_TYPE from user_objects where object_name = 'T_MY_TABLE';
OBJECT_TYPE
-------------------
VIEW
You defined a view (or other object type other than TABLE), that can't be dropped with DROP TABLE, but can be selected.
Simple check in USER_OBJECTS the OBJECT_TYPE. You may alternatively see also SYNONYM as proposed in other answer.
Note that it is not a MATERIALIZED VIEW as if you try to drop a Materialized View with DROP TABLE a different error message is raised:
ORA-12083: must use DROP MATERIALIZED VIEW to drop T_MY_TABLE
What does this return?
select * from all_synonyms
where synonym_name = 'T_MY_TABLE';
I suspect there is a synonym T_MY_TABLE that points to a table in a different schema.
drop table t_my_table purge;
Specify PURGE if you want to drop the table and release the space associated with it in a single step. If you specify PURGE, then the database does not place the table and its dependent objects into the recycle bin.
...
Using this clause is equivalent to first dropping the table and then purging it from the recycle bin. This clause lets you save one step in the process. It also provides enhanced security if you want to prevent sensitive material from appearing in the recycle bin.
Probably something different is happening.
Normal case would be:
SQL> create table t1 as select 1 a from dual;
Table T1 created.
SQL> drop table t1;
Table T1 dropped.
SQL> select * from t1;
Error starting at line : 22 in command -
select * from t1
Error at Command Line : 22 Column : 20
Error report -
SQL Error: ORA-00942: table or view does not exist
00942. 00000 - "table or view does not exist"
*Cause:
*Action:
So what was the message after the drop table?
Is t_my_table really a table?
Try select * from all_objects where lower(object_name) = 't_my_table'
Related
I am new to Oracle and for practice I have created some tables (customer, drivers, payment, booking, location, area, job, job_history) in Oracle 11g and upon select * from cat statement I have found a strange table with other created tables named "BIN$c+eOnMB3RbKSEfg/rsxtAQ==$0".I don't know why this table is created.
I tried to remove this table through
drop table BIN$c+eOnMB3RbKSEfg/rsxtAQ==$0;
but it gives error:
drop table BIN$c+*eOnMB3RbKSEfg/rsxtAQ==$0
ERROR at line 1: ORA-00933: SQL command not properly ended
what should I do to remove it?
What you see is a deleted table in the RECYCLEBIN
You may get the original name of the table with this query
SELECT original_name FROM RECYCLEBIN where OBJECT_NAME = 'BIN$c+eOnMB3RbKSEfg/rsxtAQ==$0';
Note that (with your parameter setting) if you DROP a table it is not completely removed, but moved in the recyclebin.
You may ommit this using the PURGE option.
DROP TABLE xxx PURGE;
To remove the table from the recyclebin you must qoute the name with double quotes (as this is not a valid name) and use the PURGE statement (not a DROP - which would trigger ORA-38301: can not perform DDL/DML over objects in Recycle Bin).
PURGE TABLE "BIN$c+eOnMB3RbKSEfg/rsxtAQ==$0"
Alternatively you may use the original_name obtained with the query above:
PURGE TABLE {your_original_name};
To clean up the recyclebin completely use this statement (with the propper table user)
PURGE RECYCLEBIN;
I put this code into SQL Developer's Worksheet:
CREATE TRIGGER T_testDSNa
before INSERT
on testDSNa
referencing new as new
for each ROW
BEGIN
SELECT S_testDSN.nextval INTO :NEW.SYSID FROM dual;
END;
I get this:
Error report -
ORA-00942: table or view does not exist
00942. 00000 - "table or view does not exist"
*Cause:
*Action:
Would anyone know why? This has worked for 3 previous tables until I tried to run the DDL to create a 4th. Alternatively, is there a better way to set up an autoincrementing PK?
The problem was lack of schema. Oracle Definition of a schema :
Collection of database objects, including logical structures such as
tables, views, sequences, stored procedures, synonyms, indexes,
clusters, and database links. A schema has the name of the user who
controls it.
If you want to know the objects accessible without alias. You have to look on [USER_OBJECTS]. Which describes the relational objects owned by the current user :
SELECT
OBJECT_NAME
, OBJECT_TYPE
, LAST_DDL_TIME
FROM USER_OBJECTS;
If you want to know the objects accessible to the current user :
SELECT
OWNER
, OBJECT_NAME
, OBJECT_TYPE
, LAST_DDL_TIME
FROM ALL_OBJECTS;
In your case to see your objects in the list of available tables you need:
SELECT * FROM ALL_OBJECTS WHERE OWNER = 'USER';
You can also alter the session to avoid alias :
ALTER SESSION SET current_schema = User;
For priviliges/ roles views you can look at :
SELECT * FROM USER_SYS_PRIVS;
SELECT * FROM USER_ROLE_PRIVS;
The last method but not the most secure to avoid alias. Is to log on with a user that has the same name as the schema.
Hoping that it can help
I was getting the same issue.
Solution: What I observed that my table which I created was surrounded by double quotes, which made it case sensitive.
So for each time I refer to my table, I need to surround it by double quotes.
CREATE TRIGGER T_testDSNa
before INSERT
on "testDSNa"
referencing new as new
for each ROW
BEGIN
SELECT S_testDSN.nextval INTO :NEW.SYSID FROM dual;
END;
refer this link: What exactly do quotation marks around the table name do?
ALTER TABLE testTable ADD column1 NUMBER(1) DEFAULT 0 NOT NULL AFTER column2;
Why can't I use mySql syntax in Oracle too? The above command works in MySql. Can you give me an equivalent that works?
Error report:
SQL Error: ORA-01735: invalid ALTER TABLE option
01735. 00000 - "invalid ALTER TABLE option"
I am asking if there is any way to use after clause in Oracle command that I provided?
Because SQL is a relational algebra. It doesn't care one bit about "where" columns are located within a table, only that they exist.
To get it to work in Oracle, just get rid of the after clause. The Oracle documentation for alter table is here but it boils down to:
alter table testTable
add ( column1 number(1) default 0 not null )
There is no after clause for the alter table command.
Oracle does not support adding columns in the middle of a table, only adding them to the end. Your database design and app functionality should not depend on the order of columns in the database schema. You can always specify an order in your select statement, after all.
However if for some reason you simply must have a new column in the middle of your table there is a work around.
CREATE TABLE tab1New AS SELECT 0 AS col1, col1 AS col2 FROM tab1;
DROP TABLE tab1 PURGE;
RENAME tan1New to tab1;
Where the SELECT 0 AS col1 is your new column and then you specify other columns as needed from your original table. Put the SELECT 0 AS col1 at the appropriate place in the order you want.
Afterwards you may want to run an alter table statement on the column to make sure it's the data type you desire.
Try this :
ALTER TABLE testTable ADD column1 NUMBER(1) DEFAULT 0 NOT NULL
I'm confused about Materialized views. Either it is the Toad IDE that I am using that is confusing me, or its that I don't understand MVs enough.
I created a materialized view in Oracle by something like this....
CREATE MATERIALIZED VIEW TESTRESULT
NOCACHE
LOGGING
NOCOMPRESS
NOPARALLEL
BUILD IMMEDIATE
REFRESH FORCE ON DEMAND
WITH PRIMARY KEY
AS
SELECT ...
FROM tables...
I would expect that the materialized view would be created and populated with the data returned from the query. Okay, not a big deal.
What I am confused on is why my Toad IDE shows a table 'TESTRESULT' under the tables section. It even has a 'Create Table Script' that I can look at.
But I also see my materialized view under the 'Materialized View' section.
Behind the scenes is Oracle creating a table when I create a materialized view? It looks as if there are two seperate objects, a materialized view and a table? Could someone please explain what is going on here behind the scenes when creating a materialized view? Is Toad wrong or am I misunderstanding something?
Toad version: 9.6.1.1
Oracle: 10g
Yes, behind the scenes, Oracle creates two objects, a table where the results are actually materialized and a materialized view that has all the metadata (the query, the attributes, etc.). It's very similar to what happens when you create a unique constraint-- Oracle creates a unique index with the same name as the constraint to actually enforce the constraint and then it creates a constraint itself. If you create a materialized view on a pre-built table, you can end up with different names for the table and for the materialized view just as you could create a constraint that uses an existing index that has a different name.
SQL> select object_name, object_type
2 from user_objects
3
SQL> ed
Wrote file afiedt.buf
1 select object_name, object_type
2 from user_objects
3* where object_name = 'MV_EMP'
4 /
no rows selected
SQL> create materialized view mv_emp
2 as
3 select *
4 from emp;
Materialized view created.
SQL> column object_name format a30;
SQL> select object_name, object_type
2 from user_objects
3 where object_name = 'MV_EMP';
OBJECT_NAME OBJECT_TYPE
------------------------------ -------------------
MV_EMP TABLE
MV_EMP MATERIALIZED VIEW
If we have created a view on an existing DB2 table and then drop the table. What will happen to the view ?
The view becomes invalid/inoperative. Attempts to select from it will fail.
To try it:
create table TEST_TABLE (
TEST_COL INTEGER
);
INSERT INTO TEST_TABLE VALUES(1);
SELECT * FROM TEST_TABLE;
create view TEST_VIEW AS
SELECT * FROM TEST_TABLE;
SELECT * FROM TEST_VIEW;
DROP TABLE TEST_TABLE;
SELECT * FROM TEST_VIEW;
The last statement gives the error:
[IBM][CLI Driver][DB2/NT] SQL0575N View or materialized query table
"TEST_VIEW" cannot be used because it has been marked inoperative.
SQLSTATE=51024
When a view is invalidated, as shown in the above example, DB2 will allow you to recreate that view without dropping it first. This makes it possible to re-run your view DDL files (or simply dump the TEXT column of SYSCAT.VIEWS and execute that).
Nothing happened. Just don't use that view. You can recreate the table again to use the view again later.
It becomes inoperative.
Same information can be found using following query:
SELECT viewscheama,viewname,valid FROM syscat.views
.
For the perticular view , if the "Valid" column has any value apart of 'Y' , then the view will be inoperative.