AppletTalk.com Java discussions newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Prepared Statement          AppletTalk.com Forum Index -> Java and Databases View previous topic :: View next topic   Author Message lsrinu Guest Posted: Tue Jun 06, 2006 7:10 am    Post subject: Prepared Statement Prepared Statement is used to execute a particular statement repeatedly, but where it will be loaded, where the statement is stored, is directly get the connection from the database, from where it directly get the data from database Back to top lakshmi Ashok Guest Posted: Wed Jun 07, 2006 7:10 am    Post subject: Re: Prepared Statement I could not quite understand your concern but let me try.. A query plan is generated each time a query needs to be executed. What we do with a prepared stmt is to prevent generation of this query plan each time. The query plan is placed in the cache of the database for some time which is configured by the DBA. When your code opens a connection, and tries to execute the stmt, it first searched in the cache for the statement and if it finds it , executes it...and gets data from the database. A pointer to a result set will not exist if you close the connection itself. Hence, the actual result set could be somewhere on the DB cache and the interface Result set could be just a pointer to that memory ..... this is a part I am also little bit confused about Back to top Bjorn Abelli Guest Posted: Wed Jun 07, 2006 1:57 pm    Post subject: Re: Prepared Statement "lakshmi Ashok" wrote... Quote: A query plan is generated each time a query needs to be executed. What we do with a prepared stmt is to prevent generation of this query plan each time. Not necessarily. It *can* be used in that way, but it's really up to the implementor. Not all databases makes those query plans... Quote: A pointer to a result set will not exist if you close the connection itself. Hence, the actual result set could be somewhere on the DB cache and the interface Result set could be just a pointer to that memory And that's how many drivers have it implemented, but it's not a guarantee. Not all databases uses that kind of cursors, and even if they do, it's not a guarantee that the driver will make use of it... Some drivers have more thorogh documentation on what to expect from the drivers, with possibly even more functionality built in, as the interfaces only tells us the "minimum" requirements of the implementations. E.g. if you use OraclePreparedStatements, there are additional getXxx and setXxx methods to deal with the Oracle specific types. In some drivers the implementation of Statement have even overridden the toString method in order to get a "readable" representation of the statement made, but this is not a requirement, so in many cases they have simply used the inherited method from Object. Quote: .... this is a part I am also little bit confused about To add to that confusion... The interfaces ResultSet, Statement, etc, are just that, interfaces, which are implemented by classes within the JDBC driver. Some may make use of specific database functionality and simply "forward" requests from Java, others may have it built into the driver itself, e.g. to hold a collection of the results in the memory, etc... The implementations of the interfaces varies very much, mostly depending on which database they target. The only thing the interfaces really guarantee, is that there will be some sort of implementation for each method in the implementing classes, nothing more... /// Bjorn A Inviato da X-Privat.Org - Registrazione gratuita http://www.x-privat.org/join.php Back to top lakshmi Ashok Guest Posted: Wed Jun 07, 2006 2:21 pm    Post subject: Re: Prepared Statement Am I getting this correct? There are drivers that procure the result set into the calling program memory space .. and will let me iterate the result set even after releasing the connection? Back to top Bjorn Abelli Guest Posted: Wed Jun 07, 2006 2:35 pm    Post subject: Re: Prepared Statement "lakshmi Ashok" wrote... Quote: Am I getting this correct? There are drivers that procure the result set into the calling program memory space .. and will let me iterate the result set even after releasing the connection? There *might* be, as this is completely up to the implementor. But I wouldn't count on finding any such implementations, as it's not a requirement. On the contrary, the ResultSet interface states in the API: "A ResultSet object is automatically closed when the Statement object that generated it is closed, re-executed, or used to retrieve the next result from a sequence of multiple results." http://java.sun.com/j2se/1.5.0/docs/api/java/sql/ResultSet.html If you want a "disconnected ResultSet", you have a better chance to look into any implementations of RowSet, e.g. CachedRowSet: http://java.sun.com/j2se/1.5.0/docs/api/javax/sql/rowset/CachedRowSet.html /// Bjorn A Inviato da X-Privat.Org - Registrazione gratuita http://www.x-privat.org/join.php Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         AppletTalk.com Forum Index -> Java and Databases All times are GMT Page 1 of 1   Jump to: Select a forum Java Newsgroups----------------Java DiscussionsWeb-based java games comp.lang.java 3D Graphics API's for Java Java: Support and criticism Java System Announcements comp.lang.java.api JavaBeans Java and CORBA Java and Databases comp.lang.java.developer Java GUI Toolkits Java Help comp.lang.java.javascript JVM, native methods and hardware comp.lang.java.misc Java Language Programming Security and Java comp.lang.java.setup Java Software Tools comp.lang.java.tech ibm.software.java.linux  Non-English Java Newsgroups----------------Java Language (German)Language Java (Français)Java (Italian)  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum Powered by phpBB © 2001, 2006 phpBB Group SEO toolkit © 2004-2006 webmedic.