PL/SQL的小常识

王朝mssql·作者佚名  2008-05-19
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fact:

PL/SQL 9 ,PL/SQL 8 ,PL/SQL 7

symptom:

1 Compiling PL/SQL fails

2 ORA-06550: line %s, column %s:\n%s

3 PLS-00801: internal error [%s]

4 PLS-00801: internal Error [74901]

change:

NOTE ROLE: To reproduce: declare col number(2.0); begin null; end;

cause:

Incorrectly using a '.' instead of a ',' as a DECIMAL separator in the TYPE

declaration of the PL/SQL code leads to this error. For example: as var1

NUMBER (10.0); instead of var1 NUMBER (10,0);

Bug:

#637990

PLS-801[74901] OCCURRED WHEN USED NUMBER(2.0)

INSTEAD OF NUMBER (2,0)

fix:

This is still not fixed in PL/SQL Workaround: Change '.' to ',' and recompile

the package. Example: From: var1 NUMBER (10.0); To: var1 NUMBER (10,0);

fact:

PL/SQL 9 ,PL/SQL 8 ,PL/SQL 7

EXECUTE IMMEDIATE, DBMS_SQL

symptom:

1 Calling PROCEDURE in EXECUTE IMMEDIATE fails

2 ORA-00900: invalid SQL statement

cause:

When using EXECUTE IMMEDIATE (native dynamic SQL), the SQL server expects

a valid SQL statement. A PROCEDURE/FUNCTION call on its own is not a valid

SQL statement (because it is PL/SQL), so the SQL server does not understand

the statement. The SQL server can process a PL/SQL block, however.

fix:

Embed the call to the PROCEDURE in an anonymous block - i.e. put BEGIN ...

END around it - and submit the anonymous block instead

e.g.

CREATE OR REPLACE procedure exec_proc1 (arg1 number, arg2 varchar2)

IS

BEGIN

EXECUTE IMMEDIATE 'BEGIN proc1('||arg1||', '||arg2||'); END;';

END;

or

CREATE OR REPLACE procedure exec_proc1 (arg1 number, arg2 varchar2)

IS

plsql_block := 'BEGIN proc1('||arg1||', '||arg2||'); END;';

BEGIN

EXECUTE IMMEDIATE plsql_block USING 7788, 500;

END;

Reference:

PL/SQL User's Guide and Reference

goal:

How to verify the enabled roles for a session within a trigger or

PL/SQL routine

fact:

Oracle Server - Enterprise Edition

PL/SQL

DBMS_SESSION

fix:

The view 'session_roles' lists the roles that are currently enabled to the user.

When a PL/SQL routine, like a trigger, is executed, it is executed as the owner

of the routine. Therefor querying the 'session_roles' view within a PL/SQL

routine will not give the information of the executing user session.

It is not possible to retrieve a list of enabled roles for a session within a

PL/SQL routine. By using the DBMS_SESSION.IS_ROLE_ENABLED it is possible to

check whether a role is enabled or not.

Example:

create or replace procedure ptst is

begin

if dbms_session.is_role_enabled('TEST') then

dbms_output.put_line ('Role is enabled');

else

dbms_output.put_line ('Role is NOT enabled');

end if;

end;

/

Reference:

: Function

DBMS_SESSION.IS_ROLE_ENABLED

fact:

Oracle Server - Enterprise Edition 9.0.1

Oracle Server - Enterprise Edition 8.1.6.2

HP Alpha OpenVMS 7.3

HP Tru64 UNIX 5.1

compatible = 8.0.5

symptom:

1 Executing remote packaged PROCEDURE fails

2 PLS-00801: internal error [%s]

3 internal error [1407]

4 No local or remote trace files generated

cause:

The cause of this problem is still undetermined.

fix:

Verify the version of the remote database and set the COMPATIBLE parameter of

the remote database as close as possible to that of the local database.

In this case setting compatible initSID.ora parameter to 8.1.6 from 8.0.5 on

remote site solved the problem.

fact:

PL/SQL 9 ,PL/SQL 8 ,PL/SQL 7

symptom:

The following error occurs while inserting empty blob to return blob locators.

ORA-22990: lob locator cannot span transaction

cause:

The above sql statements were executed within a for loop.

After each fetch a call to dbms_lob.copy is made followed by commit within the loop.

Fetching accross commits is not allowed since it results to cursor invalidation

because the a COMMIT release any locks held by the session.

From Oracle 8 Server Application Developer's Guide, Chapter 6, Large Objects:

The insert statement automatically starts a transaction and locks the row.

Once it has occurred, the locator may not be used outside the current

transaction, since a COMMIT release any locks.

Therefore any fetch after the lock will result in ORA-22990: LOB locators

cannot span transactions.

fix:

It is not advisable to use a COMMIT inside a loop. Use commit after the

loop ends.

reference:

Oracle 8 Server Application Developer's Guide

fact:

PL/SQL 9 ,PL/SQL 8 ,PL/SQL 7

ORA-01001 results

symptom:

Preparing a cursor in a function, but executing it in another

1. Prepare cursor in a function

2. A function is called that opens the cursor and does a fetch.

3. The function in step 2 is called again to do another fetch

and ORA-01001 results

cause:

What happened is that between calls to the function that does

the fetch the cursor cache is overwritten and the prepared

statement is being lost.

Workaround:

put the prepare, open, and fetch statements in one function.

fact:

JDBC OCI , pre-compiler

ORA-01001: maximum open cursors exceeded

symptom:

The error message “ORA-01001: maximum open cursors exceeded”

returned in a JDBC connection, even though the OPEN_CURSOR

(default = 50) has been increased.

cause:

The number of cursors one client can open at a time on a connection

is limited (50 is the default value).

If you don't close these cursors explicitly, you will get this error

eventually. Simply increasing the "OPEN_CURSORS" limit can help

you avoid the problem for a while, but that just hides the problem, not

solve it.

Workaround:

You do need to explicitly close the statement, by using the method

stmt.close() in order to close and freeup the cursors. It is your responsibility

to explicitly close out cursors that you no longer need.

 
 
 
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