View RSS Feed

Prepared Statement

Prepared Statement

  1. Batch Updates and Transactions

    by , 04-27-2012 at 07:18 PM
    It is important to keep in mind, that each update added to a Statement or PreparedStatement is executed separately by the database. That means, that some of them may succeed before one of them fails. All the statements that have succeeded are now applied to the database, but the rest of the updates may not be. This can result in an inconsistent data in the database.

    To avoid this, you can execute the batch update inside a transaction. When executed inside a transaction you can make ...
  2. PreparedStatement Performance

    by , 04-27-2012 at 07:11 PM
    It takes time for a database to parse an SQL string, and create a query plan for it. A query plan is an analysis of how the database can execute the query in the most efficient way.
    If you submit a new, full SQL statement for every query or update to the database, the database has to parse the SQL and for queries create a query plan. By reusing an existing PreparedStatement you can reuse both the SQL parsing and query plan for subsequent queries. This speeds up query execution, by decreasing ...
  3. J2EE PreparedStatement Cache

    by , 04-27-2012 at 07:10 PM
    J2EE PreparedStatement Cache is implemented using a cache inside the J2EE server connection pool manager. The J2EE server keeps a list of prepared statements for each database connection in the pool. When an application calls prepareStatement on a connection, the application server checks if that statement was previously prepared. If it was, the PreparedStatement object will be in the cache and this will be returned to the application. If not, the call is passed to the jdbc driver and the query/preparedstatement ...
  4. PreparedStatements and J2EE servers

    by , 04-27-2012 at 07:09 PM
    Things can get more complicated when we use a J2EE server. Normally, a prepared statement is associated with a single database connection. When the connection is closed, the preparedstatement is discarded. Normally, a fat client application would get a database connection and then hold it for its lifetime. It would also create all prepared statements eagerly or lazily. Eagerly means that they are all created at once when the application starts. Lazily means that they are created as they are used. ...
  5. How does a database execute a statement?

    by , 04-27-2012 at 07:09 PM
    Obviously, don't expect alot of detail here; we'll only examine the aspects important to this article. When a database receives a statement, the database engine first parses the statement and looks for syntax errors. Once the statement is parsed, the database needs to figure out the most efficient way to execute the statement. This can be computationally quite expensive. The database checks what indexes, if any, can help, or whether it should do a full read of all rows in a table. Databases use ...
  6. Supplying Values for PreparedStatement Parameters

    by , 04-27-2012 at 07:08 PM
    You must supply values in place of the question mark placeholders (if there are any) before you can execute a PreparedStatement object. Do this by calling one of the setter methods defined in the PreparedStatement class. The following statements supply the two question mark placeholders in the PreparedStatement named updateSales:

    Java Code:
    updateSales.setInt(1, e.getValue().intValue());
    updateSales.setString(2, e.getKey());
    The first argument for each of ...
  7. Overview of Prepared Statements

    by , 04-27-2012 at 07:06 PM
    Sometimes it is more convenient to use a PreparedStatement object for sending SQL statements to the database. This special type of statement is derived from the more general class, Statement, that you already know.

    If you want to execute a Statement object many times, it usually reduces execution time to use a PreparedStatement object instead.

    The main feature of a PreparedStatement object is that, unlike a Statement object, it is given a SQL statement when it is created. ...