- One ResultSet can exist per Statement or PreparedStatement at a
given time.
- You use PrepeparedStatement in the place of Statement, when the
Statement Object is used many times.
- PreparedStatement::
- with the uses of special characters, helps us in
preventing SQL injection attacks
- allow to create dynamic queries
- faster than statement
- It is FORWARD_ONLY
- it is indexed starting with 1
- The ? is a placeholder, which is going to be filled
later. In our case we will fill two values.
-
Example :
String sql1 = "UPDATE emp SET sal= ? WHERE EMPNO = ?";
ps=c.prepareStatement(sql1);
ps.setDouble(1,1000.00);
ps.setInt(2, 7369);
ps.addBatch();
- Treads : Several threads accessing server, use Statement.
- You must use a separate statement for each thread.
- The PostgreSQL™ JDBC driver is thread safe, meaning if your
application uses multiple threads, you don't have to set complex
algorithms ensuring that only one thread uses the database at a
time.
- While one thread is working the others will wait for
their turns to connect DB
- When ever a thread has to access a DB, it seeks the
consents of of manager class to crate a connection object.
- Once the thread completes its task, the handle goes back
connection manager. The downside of this system is, the
connection pool approached by different thread will
eventually would increase the load on the server, as a new
session is created for each connection object.
- PHP platform tenders Fast-CGI pm this regards,
- Prepared Statement
- Instances of PreparedStatement contain an SQL statement that
has already been compiled. This is what makes a statement
"prepared".
- Because PreparedStatement objects are precompiled, their
execution can be faster than that of Statement objects.
- The prepared statement is used to execute sql queries
- A CallableStatement : object provides a way to call stored
procedures in a standard way for all RDBMSs. A stored procedure is
stored in a database; the call to the stored procedure is what a
CallableStatement object contains
- Comparison : Edit IT
CallableStatement extends the capabilities of a PreparedStatement to
include methods that are only appropriate for stored procedure
calls. For example, the registerOutParameter() method is something
only applicable to stored procedures since they have parameters with
a direction (out, in, or in/out).
- Use CallableStatments only
when calling a stored procedure on the database, and use
PreparedStatement for executing other statements such as SELECT,
INSERT, UPDATE, etc
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