JDBC Example – Batch Update using PreparedStatement

Using Batch Update feature of PreparedStatement you can Insert, Update or Delete multiple records with single database hit. For example if you want to insert multiple records into database using Batch Update you will just need to conect to database once. You can loop through records and add it to bach and once done you can execute the bach i.e insert all records in a single shot.


Below is a code snippet which shows how to insert few records in batch process, via JDBC PreparedStatement

PreparedStatement ps=con.prepareStatement("INSERT INTO BS_Books (cat_id,book_title,book_details,book_price,book_author) values (?,?,?,?,?)");

ps.setInt(1, 1);
ps.setString(2, "Book1");
ps.setString(3, "Details of book1");
ps.setDouble(4, 100.0);
ps.setString(5, "Author1");
ps.addBatch();//Adding record to the batch

ps.setInt(1, 1);
ps.setString(2, "Book2");
ps.setString(3, "Details of book2");
ps.setDouble(4, 150.0);
ps.setString(5, "Author2");
ps.addBatch();//Adding record to the batch

ps.executeBatch();//Executing the batch

Please see the complete self explanatory java code below

Hibernate reverse engineering demo using Eclipse

Reverse Engineering: The most powerful feature of Hibernate Tools is a database reverse engineering tool that can generate domain model classes and Hibernate mapping files, annotated EJB3 entity beans, HTML documentation or even an entire JBoss Seam application in seconds. With the help of Eclipse you can do reverse Engineering. Lets see step by step to reverse-engineer database tables to generate hibernate POJO classes and mapping XML files using hibernate-tools (eclipse).

About the example: I am using My Eclipse 8.6 and MySQL. We will generate POJO classes and mapping XML files etc and latter run a test program. Please see the self explanatory screen shots below.

1. Create a New Java project

File -> New -> Java Project

Hibernate Examples - Native SQL Queries

You can also express queries in the native SQL dialect of your database. This is useful if you want to utilize database-specific features such as query hints or the CONNECT keyword in Oracle. It also provides a clean migration path from a direct SQL/JDBC based application to Hibernate.

Hibernate3 allows you to specify handwritten SQL, including stored procedures, for all create, update, delete, and load operations.

To know more, click here.

For example - we can have methods in DAO for executing Native SQL as shown below.

public List executeNativeQuery(String query) {
return getSession().createSQLQuery(query).list();
}

public List executeQuery(String query) {
return getSession().createQuery(query).list();
}

You can pass native SQL query as shown below -

List allObjects = empDao.executeNativeQuery("Select emp_id, emp_name  from EMPLOYEE");

Iterator it = allObjects.iterator();
while(it.hasNext())
{
Object row[] = (Object[])it.next();
for(Object eachRow : row) {
System.out.println(eachRow.toString());
}
}

Below are the known errors and exception -

1. Exception in thread "main" org.hibernate.MappingException: No Dialect mapping for JDBC type: -1
at org.hibernate.dialect.TypeNames.get(TypeNames.java:79)
at org.hibernate.dialect.TypeNames.get(TypeNames.java:104)
at org.hibernate.dialect.Dialect.getHibernateTypeName(Dialect.java:393)
at org.hibernate.loader.custom.CustomLoader$Metadata.getHibernateType(CustomLoader.java:582)
at org.hibernate.loader.custom.CustomLoader$ScalarResultColumnProcessor.performDiscovery(CustomLoader.java:508)
at org.hibernate.loader.custom.CustomLoader.autoDiscoverTypes(CustomLoader.java:524)
at org.hibernate.loader.Loader.getResultSet(Loader.java:1821)
at org.hibernate.loader.Loader.doQuery(Loader.java:697)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:259)
at org.hibernate.loader.Loader.doList(Loader.java:2232)
at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2129)
at org.hibernate.loader.Loader.list(Loader.java:2124)
at org.hibernate.loader.custom.CustomLoader.list(CustomLoader.java:312)
at org.hibernate.impl.SessionImpl.listCustomQuery(SessionImpl.java:1723)
at org.hibernate.impl.AbstractSessionImpl.list(AbstractSessionImpl.java:165)
at org.hibernate.impl.SQLQueryImpl.list(SQLQueryImpl.java:175)


Solution - Above exception occurs if you pass * to fetch all columns in SQL like - "Select * from EMPLOYEE". this should be avoided.

Lucene - Updating index for an existing file

Updating index files could mean below two possibilities -

• Adding a new file to existing index
• Updating an existing file

Adding a new file to an existing index

Adding a new file is very simple. Please see my previous article. click here.

Updating an existing file

When you do IndexWriter.add() for a document that is already in the index it won't overwrite the previous document instead it will add multiple copies of the same document in the index.

There is no direct update procedure in Lucene. To update an index incrementally you must first delete the documents that were updated, and then re-add them to the index. In this example we will see how to delete a file and then you can re-add the same file with the help of my previous article. click here.

How to delete a documents from the index?

IndexWriter allows you to delete by Term or by Query. The deletes are buffered and then periodically flushed to the index, and made visible once commit() or close() is called.

IndexReader can also delete documents, by Term or document number, but you must close any open IndexWriter before using IndexReader to make changes (and, vice/versa). IndexReader also buffers the deletions and does not write changes to the index until close() is called, but if you use that same IndexReader for searching, the buffered deletions will immediately take effect. Unlike IndexWriter's delete methods, IndexReader's methods return the number of documents that were deleted.

Generally it's best to use IndexWriter for deletions, unless 1) you must delete by document number, 2) you need your searches to immediately reflect the deletions or 3) you must know how many documents were deleted for a given deleteDocuments invocation.

If you must delete by document number but would otherwise like to use IndexWriter, one common approach is to make a primary key field, that holds a unique ID string for each document. Then you can delete a single document by creating the Term containing the ID, and passing that to IndexWriter's deleteDocuments(Term) method.

Once a document is deleted it will not appear in TermDocs nor TermPositions enumerations, nor any search results. Attempts to load the document will result in an exception. The presence of this document may still be reflected in the docFreq statistics, and thus alter search scores, though this will be corrected eventually as segments containing deletions are merged.

To know more, click here.

Some Smart Social Media Marketing Tips

In today world, social media is the finest and essential way to market your business successfully. It is not an easier task especially with the lack of proper knowledge and understanding about different social media marketing strategies. There is large number of social media networks such as twitter, Google plus, Facebook, my space and so on which act as the powerful medium to market business and this is the reason  many business are hiring digital media agency that are expert in marketing strategy to market your business on social media. For some extent you can also do social media marketing of your business, here are some smart tips for social media marketing:

• Post content which your target audience like to read not the content which you like to read. Many beginners write content based on their taste without considering type of the audience they are writing. Blogging about being businessman is good if your audience are business owners.

• Determine social media marketing return on investment by examining and comparing return on investment on other advertising methods. Instead of comparing each and every thing, it will be better to compare the amount of traffic different channels are driving to your site.

• Offer mobile check-in deals to provide products and services