I am trying to migrate a DB from Informix to Oracle.Informix had an option like while inserting into a table if the size of the value exceeds the column length then Informix automatically trims the data.But Oracle does not support this and always throws an exception.Is there a way to prevent and allow trim or we have to respect religiously?
There is no automatic trimming of data in Oracle, you have to trim it explicitly yourself e.g.
insert into mytable (id, text) values (123, substr(var,1,4000));
Oracle does support a variety of SQL functions which trim variables. I suspect the one you'll want is 'SUBSTR()'. The problem is that you will need to specify the desired length explicitly. In this example T23.WHATEVER is presumed to be VARCHAR2(30) and T24.TOO_LONG_COLUMN is, er, longer:
insert into t23
(id
, whatever)
select pk_col
, substr(too_long_col, 1, 30)
from t42
/
As well as Tony's suggestion, you can use a CAST
select cast ('1234' as varchar2(3)) a
from dual
If you are doing data migration, look into DML Error Logging
Having all your non-conformant data put into a corresponding table with the failure reason is positively dreamy.
Related
I have an application which is occasionally being passed data which causes it to fail with ORA-12899 error trying to insert the record into a varchar(2000) column on an Oracle 11g database. )In some cases it is trying to insert a field of more than 4000 characters.)
In the longer term, I will request a change to the application to prevent this happening, but meanwhile I need a short-term fix to allow the record to be saved, truncating the data to 2000 characters.
I've experimented with a "before insert" trigger (which works fine when truncating it from say 1500 to 1000 characters), but what I've found is that where the data is more than 2000 characters (i.e. more than the column length) the insert still fails with ORA-12899.
Is there any way round this, other than changing the database column to a CLOB?
Include the case statement similar to the following code in your insert command
insert into test_table
(column1)
values
(
(case when length('ablekkkkkkkkkkkh') > 2000 then substr('ablekkkkkkkkh',1,2000)
else 'ablekkkkkkkkkkkh' end )
);
I am using mybatis to perform a massive batch insert on an oracle DB.
My process is very simple: I am taking records from a list of files and inserting them into a specific table after performing some checks on the data.
-Each file contains an average of 180.000 records and I can have more than one file.
-Some records can be present in more than one file.
-A record is identical to another one if EVERY column matches, in other words I cannot simply perform a check on a specific field. And I have defined a constraint in my DB which makes sure this condition is satisfied.
To put it simply I want to just ignore the constraint exception Oracle will give to me in case that constraint is violated.
Record is not present?-->insert
Record is already present?--> go ahead
is this possible with mybatis?Or can I accomplish something at DB level?
I have control on both Application Server and DB so please tell me what's the most efficient way to accomplish this task (even though I'd like to avoid being too much DB dependant...)
of course, I'd like to avoid performing a select* before each insertion...given the number of records I am dealing with it would ruin my application's performances
Use the IGNORE_ROW_ON_DUPKEY_INDEX hint:
insert /*+ IGNORE_ROW_ON_DUPKEY_INDEX(table_name index_name) */
into table_name
select * ...
I'm not sure about JDBC, but at least in OCI it is possible. With batch operations you pass vectors as bind variables and you also get back vector(s) of returned IDs and also a vector of error codes.
You can also use MERGE on database server side together with custon collection types. Something like:
merge into t
using ( select * from TABLE(:var) v)
on ( v.id = t.id )
when not matched then insert ...
Where :var is bind variable of SQL type: TABLE OF <recordname>
The word "TABLE" is a construct used to cast from bind variable into a table.
Another option is to use SQL error loggin clause:
DBMS_ERRLOG.create_error_log (dml_table_name => 't');
insert into t(...) values(...) log errors reject limit unlimited;
Then after the load you will have to truncate error loging table err$_t;
another option would be to use external tables
It looks that any solution is quite a lot work to do, when compared to using sqlldr.
Ignore error with error table
insert
into table_name
select *
from selected_table
LOG ERRORS INTO SANJI.ERROR_LOG('some comment' )
REJECT LIMIT UNLIMITED;
and error table schema is :
CREATE GLOBAL TEMPORARY TABLE SANJI.ERROR_LOG (
ora_err_number$ number,
ora_err_mesg$ varchar2(2000),
ora_err_rowid$ rowid,
ora_err_optyp$ varchar2(2),
ora_err_tag$ varchar2(2000),
n1 varchar2(128)
)
ON COMMIT PRESERVE ROWS;
I have some trouble when trying to update a table by looping cursor which select from source table through dblink.
I have two database DB1, DB2.
They are two different database instance.
And I am using this following statement in DB1:
CURSOR TestCursor IS
SELECT a.*, 'A' TEST_COL_A, 'B' TEST_COL_B
FROM rpt.SOURCE#DB2 a;
BEGIN
For C1 in TestCursor loop
INSERT into RPT.TARGET
(
/*The company_name and cust_id are select from SOURCE table from DB2*/
COMPANY_NAME, CUST_ID, TEST_COL_A, TEST_COL_B
)
values
(
C1.COMPANY_NAME, C1.CUST_ID, C1.TEST_COL_A , C1.TEST_COL_B
) ;
End loop;
/*Some code...*/
End
Everything works fine until I add a column "NEW_COL" to SOURCE table#DB2
The insert data got the wrong value.
The value of TEST_COL_A , as I expect, should be 'A'.
However, it contains the value of NEW_COL which i add at SOURCE table.
And the value of TEST_COL_B contains 'A'.
Have anyone encounter the same issue?
It seems like oracle cache the table columns when it compile.
Is there any way to add a column to source table without recompile?
According to this:
Oracle Database does not manage
dependencies among remote schema
objects other than
local-procedure-to-remote-procedure
dependencies.
For example, assume that a local view
is created and defined by a query that
references a remote table. Also assume
that a local procedure includes a SQL
statement that references the same
remote table. Later, the definition of
the table is altered.
Therefore, the local view and
procedure are never invalidated, even
if the view or procedure is used after
the table is altered, and even if the
view or procedure now returns errors
when used. In this case, the view or
procedure must be altered manually so
that errors are not returned. In such
cases, lack of dependency management
is preferable to unnecessary
recompilations of dependent objects.
In this case you aren't quite seeing errors, but the cause is the same. You also wouldn't have a problem if you used explicit column names instead of *, which is usually safer anyway. If you're using * you can't avoid recompiling (unless, I suppose, the * is the last item in the select list, in which case any extra columns on the end wouldn't cause a problem - as long as their names didn't clash).
I recommend that you use a single set processing insert statement in DB1 rather than a row at a time cursor for loop for the insert, for example:
INSERT into RPT.TARGET
select COMPANY_NAME, CUST_ID, 'A' TEST_COL_A, 'B' TEST_COL_B
FROM rpt.SOURCE#DB2
;
Rationale:
Set processing will almost always out perform Row-at-a-time
processing [which is really slow-at-a-time processing].
Set processing the insert is a scalable solution. If the application will need to scale to tens of thousands of rows or millions of rows, the row-at-a-time solution will not likely scale.
Also, using the select * construct is dangerous for the reason you
encountered [and other similar reasons].
I am getting passed comma separated values to a stored procedure in oracle. I want to treat these values as a table so that I can use them in a query like:
select * from tabl_a where column_b in (<csv values passed in>)
What is the best way to do this in 11g?
Right now we are looping through these one by one and inserting them into a gtt which I think is inefficient.
Any pointers?
This solves exactly same problem
Ask Tom
Oracle does not come with a built-in tokenizer. But it is possible to roll our own, using SQL Types and PL/SQL. I have posted a sample solution in this other SO thread.
That would enable a solution like this:
select * from tabl_a
where column_b in ( select *
from table (str_to_number_tokens (<csv values passed in>)))
/
In 11g you can use the "occurrence" parameter of REGEXP_SUBSTR to select the values directly in SQL:
select regexp_substr(<csv values passed in>,'[^,]+',1,level) val
from dual
connect by level < regexp_count(<csv values passed in>,',')+2;
But since regexp_substr is somewhat expensive I am not sure if it is the most effective in terms of being the fastest.
I've heard people referring to this table and was not sure what it was about.
It's a sort of dummy table with a single record used for selecting when you're not actually interested in the data, but instead want the results of some system function in a select statement:
e.g. select sysdate from dual;
See http://www.adp-gmbh.ch/ora/misc/dual.html
As of 23c, Oracle supports select sysdate /* or other value */, without from dual, as has been supported in MySQL for some time already.
It is a dummy table with one element in it. It is useful because Oracle doesn't allow statements like
SELECT 3+4
You can work around this restriction by writing
SELECT 3+4 FROM DUAL
instead.
From Wikipedia
History
The DUAL table was created by Chuck Weiss of Oracle corporation to provide a table for joining in internal views:
I created the DUAL table as an underlying object in the Oracle Data Dictionary. It was never meant to be seen itself, but instead used
inside a view that was expected to be queried. The idea was that you
could do a JOIN to the DUAL table and create two rows in the result
for every one row in your table. Then, by using GROUP BY, the
resulting join could be summarized to show the amount of storage for
the DATA extent and for the INDEX extent(s). The name, DUAL, seemed
apt for the process of creating a pair of rows from just one. 1
It may not be obvious from the above, but the original DUAL table had two rows in it (hence its name). Nowadays it only has one row.
Optimization
DUAL was originally a table and the database engine would perform disk IO on the table when selecting from DUAL. This disk IO was usually logical IO (not involving physical disk access) as the disk blocks were usually already cached in memory. This resulted in a large amount of logical IO against the DUAL table.
Later versions of the Oracle database have been optimized and the database no longer performs physical or logical IO on the DUAL table even though the DUAL table still actually exists.
I think this wikipedia article may help clarify.
http://en.wikipedia.org/wiki/DUAL_table
The DUAL table is a special one-row
table present by default in all Oracle
database installations. It is suitable
for use in selecting a pseudocolumn
such as SYSDATE or USER The table has
a single VARCHAR2(1) column called
DUMMY that has a value of "X"
It's the special table in Oracle. I often use it for calculations or checking system variables. For example:
Select 2*4 from dual prints out the result of the calculation
Select sysdate from dual prints the server current date.
A utility table in Oracle with only 1 row and 1 column. It is used to perform a number of arithmetic operations and can be used generally where one needs to generate a known output.
SELECT * FROM dual;
will give a single row, with a single column named "DUMMY" and a value of "X" as shown here:
DUMMY
-----
X
Kind of a pseudo table you can run commands against and get back results, such as sysdate. Also helps you to check if Oracle is up and check sql syntax, etc.
The DUAL table is a special one-row table present by default in all Oracle database installations. It is suitable for use in selecting a pseudocolumn such as SYSDATE or USER
The table has a single VARCHAR2(1) column called DUMMY that has a value of "X"
You can read all about it in http://en.wikipedia.org/wiki/DUAL_table
DUAL is necessary in PL/SQL development for using functions that are only available in SQL
e.g.
DECLARE
x XMLTYPE;
BEGIN
SELECT xmlelement("hhh", 'stuff')
INTO x
FROM dual;
END;
More Facts about the DUAL....
http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:1562813956388
Thrilling experiments done here, and more thrilling explanations by Tom
DUAL we mainly used for getting the next number from the sequences.
Syntax : SELECT 'sequence_name'.NEXTVAL FROM DUAL
This will return the one row one column value(NEXTVAL column name).
another situation which requires select ... from dual is when we want to retrieve the code (data definition) for different database objects (like TABLE, FUNCTION, TRIGGER, PACKAGE), using the built in DBMS_METADATA.GET_DDL function:
select DBMS_METADATA.GET_DDL('TABLE','<table_name>') from DUAL;
select DBMS_METADATA.GET_DDL('FUNCTION','<function_name>') from DUAL;
in is true that nowadays the IDEs do offer the capability to view the DDL of a table, but in simpler environments like SQL Plus this can be really handy.
EDIT
a more general situation: basically, when we need to use any PL/SQL procedure inside a standard SQL statement, or when we want to call a procedure from the command line:
select my_function(<input_params>) from dual;
both recipes are taken from the book 'Oracle PL/SQL Recipes' by Josh Juneau and Matt Arena
The DUAL is special one row, one column table present by default in all Oracle databases. The owner of DUAL is SYS.
DUAL is a table automatically created by Oracle Database along with the data functions. It is always used to get the operating systems functions(like date, time, arithmetic expression., etc.)
SELECT SYSDATE from dual;
It's a object to put in the from that return 1 empty row. For example:
select 1 from dual;
returns 1
select 21+44 from dual;
returns 65
select [sequence].nextval from dual;
returns the next value from the sequence.