More DBA job interview questions and answers at
http://dba.fyicenter.com/Interview-Questions/
(Continued from previous question...)
Database-Side JDBC Procedures and Nested Connections
Most database-side JDBC Procedures need to share the same transaction space as the statements that called them for the following reasons:
* to avoid blocking and deadlocks
* to ensure that any updates done from within the method are atomic with the outer transaction
In order to use the same transaction, the procedure must use the same connection as the parent SQL statement in which the method was executed. Connections re-used in this way are called nested connections.
Use the connection URL jdbc:default:connection to re-use the current Connection
The Database Connection URL jdbc:default:connection allows a Java method to get the Connection of the SQL statement that called it. This is the standard (SQL standard, Part 13 SQL Routines and Java) mechanism to obtain the nested connection object. The method would get a Connection like this:
Connection conn = DriverManager.getConnection(
"jdbc:default:connection");
Loading a JDBC driver in a database-side routine is not required.
(Continued on next question...)
