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Programming Articles
Page 2501 of 2547
How to get the current value of a particular row from a database using JDBC?
The refreshRow() method of the ResultSet interface refreshes the current row with the most recent value in the database.rs.refreshRow()Assume we have a table named cricketers_data with 7 records as shown below:+----+------------+------------+---------------+----------------+-------------+ | ID | First_Name | Last_Name | Year_Of_Birth | Place_Of_Birth | Country | +----+------------+------------+---------------+----------------+-------------+ | 1 | Shikhar | Dhawan | 1981-12-05 | Delhi | India | | 2 | Jonathan | Trott | 1981-04-22 | CapeTown | SouthAfrica | | 3 | Lumara | Sangakkara | ...
Read MoreWhat is autoFlush attribute in JSP?
The autoFlush attribute specifies whether the buffered output should be flushed automatically when the buffer is filled, or whether an exception should be raised to indicate the buffer overflow.A value of true (default) indicates automatic buffer flushing and a value of false throws an exception.The following directive causes the servlet to throw an exception when the servlet's output buffer is full −This directive causes the servlet to flush the output buffer when full −Usually, the buffer and the autoFlush attributes are coded on a single page directive as follows −
Read MoreWhat is contentType attribute in JSP?
The contentType attribute sets the character encoding for the JSP page and for the generated response page. The default content type is text/html, which is the standard content type for HTML pages.If you want to write out XML from your JSP, use the following page directive −The following statement directs the browser to render the generated page as HTML −The following directive sets the content type as a Microsoft Word document −You can also specify the character encoding for the response. For example, if you wanted to specify that the resulting page that is returned to the browser uses ISO ...
Read MoreHow to connect to PostgreSQL database using a JDBC program?
PostgreSQL is an open source relational database management system (DBMS) developed by a worldwide team of volunteers. PostgreSQL is not controlled by any corporation or other private entity and the source code is available free of charge.PostgreSQL runs on all major operating systems, including Linux, UNIX (AIX, BSD, HP-UX, SGI IRIX, Mac OS X, Solaris, Tru64), and Windows. It supports text, images, sounds, and video, and includes programming interfaces for C / C++, Java, Perl, Python, Ruby, Tcl and Open Database Connectivity (ODBC).Download the latest version of postgresql- from postgresql-jdbc repository.Add downloaded jar file postgresql-(VERSION).jdbc.jar in your class path.ExampleFollowing JDBC program ...
Read MoreWhat is errorPage attribute in JSP?
The errorPage attribute tells the JSP engine which page to display if there is an error while the current page runs. The value of the errorPage attribute is a relative URL.The following directive displays MyErrorPage.jsp when all uncaught exceptions are thrown −The isErrorPage attribute indicates that the current JSP can be used as the error page for another JSP.The value of isErrorPage is either true or false. The default value of the isErrorPage attribute is false.For example, handleError.jsp sets the isErrorPage option to true because it is supposed to handle errors −
Read MoreWhat are important server response headers that are useful in web programming?
Following is a summary of the most useful HTTP 1.1 response headers which go back to the browser from the web server. These headers are frequently used in web programming −Sr.No.Header & Description1AllowThis header specifies the request methods (GET, POST, etc.) that the server supports.2Cache-ControlThis header specifies the circumstances in which the response document can safely be cached. It can have values public, private or no-cache etc. Public means document is cacheable, Private means document is for a single user and can only be stored in private (nonshared) caches and no-cache means document should never be cached.3ConnectionThis header instructs the ...
Read MoreWrite an example JDBC program demonstrating the batch processing with CallableStatement object?
Grouping related SQL statements into a batch and executing/submitting them at once is known as batch processing. The Statement interface provides methods to perform batch processing such as addBatch(), executeBatch(), clearBatch().Follow the steps given below to perform batch updates using the CallableStatement object:Register the driver class using the registerDriver() method of the DriverManager class. Pass the driver class name to it, as a parameter.Connect to the database using the getConnection() method of the DriverManager class. Passing URL (String), username (String), password (String) as parameters to it.Set the auto-commit to false using setAutoCommit() method of the Connection interface.Create a CallableStatement object ...
Read MoreHow to group queries using transaction in a JSP?
The tag is used to group the and tags into transactions. You can put as many and tags as statements inside the tag to create a single transaction.It ensures that the database modifications performed by the nested actions are either committed or rolled back if an exception is thrown by any nested action.AttributeThe tag has the following attributes −AttributeDescriptionRequiredDefaultdataSourceDatabase connection to use (overrides the default)NoDefault databaseisolationTransaction isolation (READ_COMMITTED, READ_UNCOMMITTED, REPEATABLE_READ, or SERIALIZABLE)NoDatabase’s defaultExampleTo start with the basic concept, let us create a Students table in the TEST database and create a few records ...
Read MoreHow to retrieve multiple ResultSets from a stored procedure using a JDBC program?
Stored procedures are sub routines, segment of SQL statements which are stored in SQL catalog. All the applications that can access Relational databases (Java, Python, PHP etc.), can access stored procedures.Stored procedures contain IN and OUT parameters or both. They may return result sets in case you use SELECT statements. Stored procedures can return multiple result sets.Retrieving Results from a procedure:You can call an existing stored procedure using the CallableStatement. The prepareCall() method of the Connection interface accepts the procedure call in string format and returns a callable statement object.CallableStatement cstmt = con.prepareCall("{call sampleProcedure()}");Execute the above created callable statement using ...
Read MoreHow do I find out whether the underlying database supports batch processing?
Not all the databases support batch processing therefore before proceeding with batch updates in your application. You need to verify whether the database you are trying to communicate supports batch processing/batch updates or not.You can do so using the supportsBatchUpdates() method of the DatabaseMetaData interface.Follow the steps given below:Register the driver class using the registerDriver() method of the DriverManager class. Pass the driver class name to it, as a parameter.Connect to the database using the getConnection() method of the DriverManager class. Passing URL (String), username (String), password (String) as parameters to it.Create a DatabaseMetaData object using the getMetaData() method of ...
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