The JDBC 3.0 API is the latest update of the JDBC API. It contains many features, including scrollable result sets and the SQL:1999 data types. 3. Does the JDBC-ODBC Bridge support the new features in the JDBC 3.0 API? The JDBC-ODBC Bridge provides a limited subset of the JDBC 3.0 API. 4. Can the JDBC-ODBC Bridge be used with applets? Use of the JDBC-ODBC bridge from an untrusted applet running in a browser, such as Netscape Navigator, isn't allowed. The JDBC-ODBC bridge doesn't allow untrusted code to call it for security reasons. This is good because it means that an untrusted applet that is downloaded by the browser can't circumvent Java security by calling ODBC. Remember that ODBC is native code, so once ODBC is called the Java programming language can't guarantee that a security violation won't occur. On the other hand, Pure Java JDBC drivers work well with applets. They are fully downloadable and do not require any client-side configuration. Finally, we would like to note that it is possible to use the JDBC-ODBC bridge with applets that will be run in appletviewer since appletviewer assumes that applets are trusted. In general, it is dangerous to turn applet security off, but it may be appropriate in certain controlled situations, such as for applets that will only be used in a secure intranet environment. Remember to exercise caution if you choose this option, and use an all-Java JDBC driver whenever possible to avoid security problems. 5. How do I start debugging problems related to the JDBC API? A good way to find out what JDBC calls are doing is to enable JDBC tracing. The JDBC trace contains a detailed listing of the activity occurring in the system that is related to JDBC operations. If you use the 6. How can I use the JDBC API to access a desktop database like Microsoft Access over the network? Most desktop databases currently require a JDBC solution that uses ODBC underneath. This is because the vendors of these database products haven't implemented all-Java JDBC drivers. The best approach is to use a commercial JDBC driver that supports ODBC and the database you want to use. See the JDBC drivers page for a list of available JDBC drivers. The JDBC-ODBC bridge from Sun's Java Software does not provide network access to desktop databases by itself. The JDBC-ODBC bridge loads ODBC as a local DLL, and typical ODBC drivers for desktop databases like Access aren't networked. The JDBC-ODBC bridge can be used together with the RMI-JDBC bridge, however, to access a desktop database like Access over the net. This RMI-JDBC-ODBC solution is free. 7. Are there any ODBC drivers that do not work with the JDBC-ODBC Bridge? Most ODBC 2.0 drivers should work with the Bridge. Since there is some variation in functionality between ODBC drivers, the functionality of the bridge may be affected. The bridge works with popular PC databases, such as Microsoft Access and FoxPro. 8. What causes the "No suitable driver" error? "No suitable driver" is an error that usually occurs during a call to the In addition, when you are using the JDBC-ODBC Bridge, this error can occur if one or more the the shared libraries needed by the Bridge cannot be loaded. If you think this is the cause, check your configuration to be sure that the shared libraries are accessible to the Bridge. 9. Why isn't the This problem can be caused by running a JDBC applet in a browser that supports the JDK 1.0.2, such as Netscape Navigator 3.0. The JDK 1.0.2 does not contain the JDBC API, so the Here's a solution that doesn't require any additional configuration of your web clients. Remember that classes in the This solution will allow your applet to work in any client browser that supports the JDK 1.0.2. Your applet will also work in browsers that support the JDK 1.1, although you may want to switch to the JDK 1.1 classes for performance reasons. Also, keep in mind that the solution outlined here is just an example and that other solutions are possible. The This type of error occurs during an attempt to connect to a database with the bridge. First, note that the error is coming from the ODBC driver manager. This indicates that the bridge-which is a normal ODBC client-has successfully called ODBC, so the problem isn't due to native libraries not being present. In this case, it appears that the error is due to the fact that an ODBC DSN (data source name) needs to be configured on the client machine. Developers often forget to do this, thinking that the bridge will magically find the DSN they configured on their remote server machine. 12. Are all the required JDBC drivers to establish connectivity to my database part of the JDK? No. There aren't any JDBC technology-enabled drivers bundled with the JDK 1.1.x or Java 2 Platform releases other than the JDBC-ODBC Bridge. So, developers need to get a driver and install it before they can connect to a database. We are considering bundling JDBC technology- enabled drivers in the future. 13. Is the JDBC-ODBC Bridge multi-threaded? No. The JDBC-ODBC Bridge does not support concurrent access from different threads. The JDBC-ODBC Bridge uses synchronized methods to serialize all of the calls that it makes to ODBC. Multi-threaded Java programs may use the Bridge, but they won't get the advantages of multi-threading. In addition, deadlocks can occur between locks held in the database and the semaphore used by the Bridge. We are thinking about removing the synchronized methods in the future. They were added originally to make things simple for folks writing Java programs that use a single-threaded ODBC driver. 14. Does the JDBC-ODBC Bridge support multiple concurrent open statements per connection? No. You can open only one 15. Why can't I invoke the You are probably using a driver implemented for the JDBC 1.0 API. You need to upgrade to a JDBC 2.0 driver that implements scrollable result sets. Also be sure that your code has created scrollable result sets and that the DBMS you are using supports them. 16. How can I retrieve a Creating and garbage collecting potentially large numbers of objects (millions) unnecessarily can really hurt performance. It may be better to provide a way to retrieve data like strings using the JDBC API without always allocating a new object. We are studying this issue to see if it is an area in which the JDBC API should be improved. Stay tuned, and please send us any comments you have on this question. No, but it is easy to find the number of rows. If you are using a scrollable result set, The JDBC-ODBC Bridge is bundled with the Java 2 SDK, Standard Edition, so there is no need to download it separately. 19. If I use the JDBC API, do I have to use ODBC underneath? No, this is just one of many possible solutions. We recommend using a pure Java JDBC technology-enabled driver, type 3 or 4, in order to get all of the benefits of the Java programming language and the JDBC API. You still need to get and install a JDBC technology-enabled driver that supports the database that you are using. There are many drivers available from a variety of sources. You can also try using the JDBC-ODBC Bridge if you have ODBC connectivity set up already. The Bridge comes with the Java 2 SDK, Standard Edition, and Enterprise Edition, and it doesn't require any extra setup itself. The Bridge is a normal ODBC client. Note, however, that you should use the JDBC-ODBC Bridge only for experimental prototyping or when you have no other driver available. 21. What are the different types of JDBC drivers?
JDBC - Frequently Asked Questions or Interview Questions(FAQs)
1. What is JDBC?
JDBC technology is an API that lets you access virtually any tabular data source from the Java programming language. It provides cross-DBMS connectivity to a wide range of SQL databases, and now, with the new JDBC API, it also provides access to other tabular data sources, such as spreadsheets or flat files.
2. What's the JDBC 3.0 API?
DriverManager facility to establish your database connection, you use the DriverManager.setLogWriter method to enable tracing of JDBC operations. If you use a DataSource object to get a connection, you use the DataSource.setLogWriter method to enable tracing. (For pooled connections, you use the ConnectionPoolDataSource.setLogWriter method, and for connections that can participate in distributed transactions, you use the XADataSource.setLogWriter method.)DriverManager.getConnection method. The cause can be failing to load the appropriate JDBC drivers before calling the getConnection method, or it can be specifying an invalid JDBC URL--one that isn't recognized by your JDBC driver. Your best bet is to check the documentation for your JDBC driver or contact your JDBC driver vendor if you suspect that the URL you are specifying is not being recognized by your JDBC driver.java.sql.DriverManager class being found?DriverManager class typically isn't found by the Java virtual machine running in the browser.java.* packages cannot be downloaded by most browsers for security reasons. Because of this, many vendors of all-Java JDBC drivers supply versions of the java.sql.* classes that have been renamed to jdbc.sql.*, along with a version of their driver that uses these modified classes. If you import jdbc.sql.* in your applet code instead of java.sql.*, and add the jdbc.sql.* classes provided by your JDBC driver vendor to your applet's codebase, then all of the JDBC classes needed by the applet can be downloaded by the browser at run time, including the DriverManager class.ResultSet.getXXX methods are the only way to retrieve data from a ResultSet object, which means that you have to make a method call for each column of a row. It is unlikely that this is the cause of a performance problem, however, because it is difficult to see how a column could be fetched without at least the cost of a function call in any scenario. We welcome input from developers on this issue.Statement object per connection when you are using the JDBC-ODBC Bridge.ResultSet methods afterLast and beforeFirst when the method next works?String or other object type without creating a new object each time?rs, you can call the methods rs.last and then rs.getRow to find out how many rows rs has. If the result is not scrollable, you can either count the rows by iterating through the result set or get the number of rows by submitting a query with a COUNT column in the SELECT clause.
JDBC technology drivers fit into one of four categories:
- A JDBC-ODBC bridge provides JDBC API access via one or more ODBC drivers. Note that some ODBC native code and in many cases native database client code must be loaded on each client machine that uses this type of driver. Hence, this kind of driver is generally most appropriate when automatic installation and downloading of a Java technology application is not important. For information on the JDBC-ODBC bridge driver provided by Sun, see JDBC-ODBC Bridge Driver.
- A native-API partly Java technology-enabled driver converts JDBC calls into calls on the client API for Oracle, Sybase, Informix, DB2, or other DBMS. Note that, like the bridge driver, this style of driver requires that some binary code be loaded on each client machine.
- A net-protocol fully Java technology-enabled driver translates JDBC API calls into a DBMS-independent net protocol which is then translated to a DBMS protocol by a server. This net server middleware is able to connect all of its Java technology-based clients to many different databases. The specific protocol used depends on the vendor. In general, this is the most flexible JDBC API alternative. It is likely that all vendors of this solution will provide products suitable for Intranet use. In order for these products to also support Internet access they must handle the additional requirements for security, access through firewalls, etc., that the Web imposes. Several vendors are adding JDBC technology-based drivers to their existing database middleware products.
- A native-protocol fully Java technology-enabled driver converts JDBC technology calls into the network protocol used by DBMSs directly. This allows a direct call from the client machine to the DBMS server and is a practical solution for Intranet access. Since many of these protocols are proprietary the database vendors themselves will be the primary source for this style of driver. Several database vendors have these in progress.
22. Are there recommended programming practices for using JDBC connections?
The general rule is to get the connection from the connection pool as late as possible and give it back to the connection pool as soon as possible. Ensure that the connection is a method variable, and get and release the connection within the same method as where you use it (each thread should have its own connection). The cost of getting the connection is small, the prepared statement cache will reduce the preparation time, the set statements are small, the execute needs to be done no matter what the usage, and the close is small. It is not recommended to
create the connection at ejbCreate/activate and close it on ejbRemove/pasivate.
23. Why should I not use DriverManager.getConnection?
DriverManager.getConnection can cause a deadlock. In the server, all DriverManager calls are class-synchronized including many frequent calls that all drivers make, and JDBC drivers do a lot of synchronization internally. One long-waiting call can stop all JDBC work in the whole JVM and cause deadlocks. Also, you should not reregister the driver repeatedly. Regardless of the DBMS state, the one driver that is initially loaded at startup will always work.
24. Can I use a prepared statement across multiple transactions?
Yes. Every transaction uses a dedicated JDBC connection, and all database interaction needs to use this connection object in order to participate in the transaction. So a prepared statement is tied to a particular connection and can't be shared with other connections. But a prepared statement can span transactions.
25. Why do I get a java.lang.AbstractMethodError when calling a method on a driver?
This usually indicates that the driver has not implemented the method. For instance, you might be calling a JDBC 3.0 method on a driver that has only implemented the JDBC 2.0 methods.
26. Why do I get "ResourceException: No Resource Available"?
One common reason is that you have too many consumers (connection users) for the number of configured JDBC connections in the connection pool or execute threads on the server.
Another reason may be that the refresh testing process has reserved one or more connections for testing so these connections are briefly unavailable.
27. How do I ensure that a new database connection is created each time an EJB's container-managed transaction is started (so that I get a new authentication/authorization each time)?
The EJB should be tx-requires, which means it will start a transaction when called if one is not underway already, or will join the transaction in progress if there is one. Your code will use the standard JTS/JTA API to obtain and start a UserTransaction. Then you should obtain your JDBC connection from a tx data source, and it will be included in the transaction. To get a new connection each time, you could use the dynamic pool API to make a one-connection pool. We suggest configuring the server to have a one-connection pool and a tx data source for it at startup. Then when you want to do a transaction in an external client, you would destroy the initial pool and recreate it with the DBMS user you want. This will allow you to use the tx data source to get a connection, which if obtained in the context of a running UserTransaction, will get automatically included in the tx.
28. If it is a WebLogic DataSource, then you get a stub for the Connection instance, not a connection pool in the local process.
If a distributed transaction involves JMS and JDBC, how do I ensure that the JDBC update is available when the JMS message is processed?The problem is that an application can receive the JMS message from the destination before the associated JDBC data is in the database.
Distributed transactions guarantee all involved changes will either succeed or fail as a unit, but cannot guarantee that they will happen exactly simultaneously (the transaction manager instructs all resource managers to commit but cannot control the timing of the completion of that operation).
For the WebLogic transaction manager, if the JDBC connection pool and the JMS server are both on the same server, and the transaction starts on the same server, the changes are committed in the order in which they were asked for by the transaction. This is not supported behavior, it just happens to be the current behavior. So if you can co-locate JMS and the JDBC connection pool, then you may have a chance.
You could send the JMS message with a delayed birth-time, and hope that this is good enough.
If the receiver fails to find the associated JDBC record, it could rollback/recover the message. You could use the WebLogic JMS redelivery delay feature to prevent the message from being redelivered instantly.
29. If an application calls DataSource.getConnection multiple times in the same thread and transaction, will WebLogic Server handle giving me the same connection and transaction?
A common scenario might be to have multiple methods that are called within a transaction (begin/commit) that do something like the following:
Context ctx = new InitialContext();
DataSource ds = (javax.sql.DataSource) ctx.lookup("connpoll");
// work using Connection
In this case, all of the work will be done within the transaction and the same underlying JDBC connection will be used as long as the DataSource ds is a tx data source.
30. Why do I get a SystemException failure when trying to enlist my XAResource in a client?
WebLogic Server does not allow you to register or enlist an XA resource on a client. The reason for this restriction is that a client is deemed to be less reliable than a server in terms of availability. This is also why a client is not allowed to act as a transaction coordinator and register Synchronization objects.
Your client could invoke a remote object on a server that accesses the resource within a transaction. If it's a JDBC resource, then you can configure a JDBCConnectionPool and JDBCTxDataSource using an Oracle XA driver (Oracle thin or WebLogic Type 4 driver for Oracle) and obtain a connection from the data source. Or the client could look up the data source using JNDI and retrieve and manipulate a connection in a transaction. Transaction enlistment is performed automatically.
31. What causes an OCIW32.dll error?
You may see the following error message when using your JDBC driver for Oracle: "The ordinal 40 could not be loaded in the dynamic link library OCIW32.dll." This problem is caused by an out-of-date version of OCIW32.DLL in your system directory. Some programs install this file in the system directory in order to run. If you remove this file from the system directory you should no longer receive this error.
32. What type of object is returned by ResultSet.getObject() when using the WebLogic jDriver for Oracle?
WebLogic jDriver for Oracle always returns a Java object that preserves the precision of the data retrieved. It returns the following from the getObject() method:
- For columns of types NUMBER(n) and NUMBER(m,n): a Double is returned if the defined precision of the column can be represented by a Double; otherwise BigDecimal is returned.
- For columns of type NUMBER: Because there is no explicit precision, the Java type to return is determined based on the actual value in each row, and this may vary from row to row. An Integer is returned if the value has a zero-valued fractional component and the value can be represented by an integer.
For example, 1.0000 will be an integer. A long is returned for a value such as 123456789123.00000. If a value has a non-zero fractional component, a Double is returned if the precision of the value can be represented by a Double; otherwise a BigDecimal is returned.
33. How do I call Oracle stored procedures that take no parameters?
Try this:
CallableStatement cstmt = conn.prepareCall("Begin procName;
END;");
cstmt.execute();
where procName is the name of an Oracle stored procedure. This is standard Oracle SQL syntax that works with any Oracle DBMS. You can also use the following syntax:
CallableStatement cstmt = conn.prepareCall("{call procName};");
cstmt.execute();
This code, which conforms to the Java Extended SQL specification, will work with any DBMS, not just Oracle.
34. How do I bind string values in a PreparedStatement?
Suppose you are trying to get the PreparedStatement class to bind Strings in a statement. The setString() method doesn't seem to work. Here is how you have set up the PreparedStatement:
String pstmt = "select n_name from n_table where n_name LIKE '?%'";
PreparedStatement ps = conn.prepareStatement(pstmt);
ps.setString(1, "SMIT");
ResultSet rs = ps.executeQuery();
The preceding code does not work because the complete value needs to be specified in a String (without using embedded quotes) and then bound to an unquoted question mark (?). Here is the corrected code:
String matchvalue = "smit%";
String pstmt = "select n_name from n_table where n_name LIKE ?";
PreparedStatement ps = conn.prepareStatement(pstmt);
ps.setString(1, matchvalue);
ResultSet rs = ps.executeQuery();
35. Why do I get unexpected characters from 8-bit character sets in WebLogic jDriver for Oracle?
If you are using an Oracle database with an 8-bit character set on Solaris, make sure you set NLS_LANG to the proper value on the client. If NLS_LANG is not set, it defaults to a 7-bit ASCII character set, and tries to map characters greater than ASCII 128 to a reasonable approximation (for example, á, à, â would all map to a). Other characters are mapped to a question mark (?).
36. How do I learn what codesets are available in Oracle?
To find out what codesets you currently have available in Oracle, execute the following SQL query from SQLPlus at the command line:
SQL> SELECT value FROM v$nls_valid_values
WHERE parameter='CHARACTERSET';
The response lists all codesets currently installed on your system. This listing will look something like the following shortened list:
VALUE
-----------------------------------------------------------
US7ASCII
WE8DEC
WE8HP
US8PC437
WE8EBCDIC37
WE8EBCDIC500
WE8EBCDIC285
...
If you want to constrain the value in the query to a specific codeset you are searching for, you can use a SQL query like the following:
SQL> SELECT value FROM v$nls_valid_values
WHERE parameter='CHARACTERSET' and VALUE='AL24UTFFSS';
This would produce the following response if the codeset is installed:
VALUE
-------------------------------------------------------------
AL24UTFFSS
You can use Oracle's installation tools to install additional codesets. Contact Oracle for more information.
37. How do I look up an "ORA" SQLException?
If your WebLogic jDriver for Oracle application produces an SQLException, you can look up the Oracle error by using the oerr command. For example, if you see the following SQLException:
java.sql.SQLException: ORA-12536: TNS: operation would block
You can find the description of error ORA-12536 can be found with the command:
38. What is error "ORA-6502?"> oerr ora 12536
The default length of a string bound to an OUTPUT parameter of a CallableStatement is 128 characters. If the value you assign to the bound parameter exceeds that length, you will get this error.
You can adjust the length of the value of the bound parameter by passing an explicit length with the scale argument to the CallableStatement.registerOutputParameter() method.
39. Why do I get an error while trying to retrieve the text for ORA-12705?
This error occurs when you have not set the ORACLE_HOME environment variable properly. In order to use WebLogic jDriver for Oracle, the Oracle client software needs to be installed and ORACLE_HOME must be set.
You may also see this error message if you try to use WebLogic jDriver for Oracle's internationalization capabilities with a language/codeset combination that is not installed on your system. If you get the ORA-12705 error with the correct error text, then either you have set NLS_LANG improperly, or you do not have the right codesets installed on your system.
40. Why do I run out of resources during updates with Oracle's database link?
When you use Oracle's database link to update your database, you may get error "maximum number of temporary table locks exceeded" even if you close your result sets and statements when you finish.
The database link is an object in the local database that allows you to access tables, views, and so forth in a remote database. The database link is controlled by the Oracle server, so the driver has no control over its use of resources. The link appears to perform the commit (since other processes could see the records that were being created), but it doesn't free any resources until the connection is closed. The solution is to remove the database link and use the JDBC driver to do your selects, inserts, and updates.
41. Why does executing the PreparedStatement class cause a "TRUNC fails: ORA-00932: inconsistent datatypes" error?
According to Oracle Metalink Bug Database Doc ID: 144784.1, in the absence of explicit data typecasting, OCI assumes that a bind variable is a CHAR data type. If the SQL statement intends to use the bind variable as a DATE data type, but OCI thought it was a CHAR, the SQL parser will have a conflict in data types. The fix is to explicitly use data conversion functions to convert the bind variables in the problem queries. For example, a select string of
String st = "select count(*) from simple_table where TRUNC(mydate) = TRUNC(?)";
42. How do I create and update Oracle Blob fields?String st = "select count(*) from simple_table where TRUNC(mydate) = TRUNC(TO_DATE(?))";
The following code sample shows how to create and update Oracle Blob fields.
public void insert() throws SQLException {
try {
// Connect to the database using WebLogic JDBC connection pool
Hashtable ht = new Hashtable();
ht.put(Context.INITIAL_CONTEXT_FACTORY,
"weblogic.jndi.WLInitialContextFactory");
ht.put(Context.PROVIDER_URL, "t3://localhost:7001");
InitialContext ctx = new InitialContext(ht);
javax.sql.DataSource ds = (javax.sql.DataSource)
ctx.lookup("java:comp/env/jdbc/DSName");
Connection conn = ds.getConnection();
// This is necessary in any case where you are doing
// a select for update. Not doing this will result in a ORA-1002
conn.setAutoCommit (false);
BLOB blob = null;
// Create a Statement
Statement stmt = conn.createStatement ();
// Drop the table if it exists
try {
stmt.execute ("drop table ImageTable");
System.out.println("Table droped ...");
}
catch (SQLException e) {
System.out.println("Table does not exist");
}
// Create the table
stmt.execute ("create table ImageTable (column1 varchar2(20),
image BLOB)");
System.out.println("Table created ...");
// create a blob entry in the table
stmt.execute("insert into ImageTable values ('one', empty_blob())");
stmt.execute("commit");
System.out.println("inserted empty blob");
String cmd = "select * from ImageTable for update";
ResultSet rset = stmt.executeQuery(cmd);
if (rset.next()) {
blob = ((OracleResultSet)rset).getBLOB(2);
System.out.println("got blob reference");
}
else System.out.println("no row to get!!!!");
rset.close();
blob = readFromFile();
cmd = "update ImageTable set image = ? where column1 = 'one'";
PreparedStatement pstmt = conn.prepareStatement(cmd);
pstmt.setBlob(1, blob);
pstmt.execute();
stmt.execute("commit");
System.out.println("blob updated");
blob = null;
cmd = "select * from ImageTable for update";
rset = stmt.executeQuery(cmd);
if (rset.next()) {
System.out.println("get blob");
blob = ((OracleResultSet)rset).getBLOB(2);
// do something with blob
}
else
System.out.println("no row to get (2)!!!!");
}
catch (SQLException sqle) {
System.out.println("SQL Exception occured: " + sqle.getMessage());
sqle.printStackTrace();
}
catch(FileNotFoundException e) {
System.out.println("File Not Found");
}
catch (IOException ioe) {
System.out.println("IO Exception" + ioe.getMessage());
}
catch (Exception ioe) {
System.out.println("Exception" + ioe.getMessage());
}
43. How do I enlist an Oracle XAResource?}
This code will only work on the server side. It cannot be run in a client. Also note that enlistment is generally done transparently for JDBC resources that implement XAResource.
// Here is the XAResource for oracle
String URL = "jdbc:oracle:thin:@DbmsHost:DbmsPort:DbmsName";
DriverManager.registerDriver(new OracleDriver());
// Create XA Connection
OracleXADataSource oxds1 = new OracleXADataSource();
oxds1.setURL(URL);
oxds1.setUser("scott");
oxds1.setPassword("tiger");
javax.sql.XAConnection pc1 = oxds1.getXAConnection();
m_oracleResource = pc1.getXAResource ();
m_oracleConnection = pc1.getConnection();
// Here is the source code for getting the TM.
Context ctx = null;
Hashtable env = new Hashtable();
env.put(Context.INITIAL_CONTEXT_FACTORY,
"weblogic.jndi.WLInitialContextFactory");
// Parameters for the WebLogic Server.
// Substitute the correct hostname, port number
// user name, and password for your environment:
env.put(Context.PROVIDER_URL, "t3://localhost:7001");
env.put(Context.SECURITY_PRINCIPAL, "system");
env.put(Context.SECURITY_CREDENTIALS, "managers");
ctx = new InitialContext(env);
m_tManager =
(TransactionManager)ctx.lookup("javax.transaction.TransactionManager");
//Here is the source code for registering the TM.
m_tManager.begin();
m_transaction = m_tManager.getTransaction();
weblogic.transaction.TransactionManager weblogicTManager =
((weblogic.transaction.TransactionManager) m_tManager);
weblogicTManager.registerStaticResource("oracle",m_oracleResource);
44. Why do I get "ORA-00600" ?// enlist the resources with the transaction
m_transaction.enlistResource(m_oracleResource);
This error generally means that version of Oracle server is newer than version of the driver you are using. In case you are using the Oracle thin driver, you will need to download the latest ojdbc14.jar from Oracle and put it at the beginning of your CLASSPATH (and possibly update any scripts that start the server, such as startweblogic.cmd, since they override the CLASSPATH).
45. Why do I get "ORA-24327" ?
This error generally means that the environment ORACLE_HOME is not set or is set incorrectly or the D_LIBRARY_PATH or PATH does not include the right dynamic link libraries. It can also indicate a mismatch when trying to use weblogic.jdbc.oci.Driver with an earlier or later version of the Oracle client software than is supported. In that case, try to use the Oracle Thin driver instead.
46. Why do I get "java.sql.SQLException: getOBJECT is not supported by the WebLogic JDBC Driver"?
When using the WebLogic JDBC connection pool and weblogic.jdbc.vendor.oracle.OracleResultSet, the error is returned (where OBJECT is the name of some Oracle object). It implies that this feature is not supported by WebLogic Server JDBC because the object type is not serializable. There are two alternatives.
- You can switch to using the Oracle thin driver directly. That means that you will get a connection directly to the database using the Thin driver instead of getting the connection from a pool of JDBC connections. That means that you lose all advantages of using the WebLogic Server JDBC subsystem, such as transactions, connection pooling, and caching of prepared statements.
- BEA recommends moving your processing to a stored procedure.
47. Why do I get an "ORA-01453" when I use SET TRANSACTION?
When using Oracle, the message "java.sql.SQLException: ORA-01453: SET TRANSACTION must be first statement of transaction" may be logged. This is due to a limitation in the Oracle interfaces, starting in Oracle 8.1.7. WebLogic tries to minimize the problem by not calling SET TRANSACTION if the mode already matches the current state.
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