JDBC FAQ Part12

26:  How to perform  updations on Database throws Updatable ResultSet?

By using Updatable ResulSet object we are able to perform some updations on to the database. To perform updations on to the database through Updatable ResultSet object we will use the following steps.
Step1:  Get the Updatable ResultSet objectd with the fetched data.
Step2:  Move ResultSet cursor to a record where we want to perform updations, for this we will use the following method.
                        public void absolute(int recordno.)
Step3:  Perform Temporary updations on to the particular record, for this we will use following method.
                        public void updateXxx(int fieldno,xxx value)
Step4:  Make the temporary updation as a parmenent updation on to the Updatable ResultSet object as well as to the database. For this we will use the following method.
                        public void updateRow()

The following example demonstrates how to perform updations on to the database through Updatable ResultSet object.

import java.sql.*;
public class UpdateResEx1
{
            public static void main(String[] args)throws Exception
            {
                        Class.forName(“sun.jdbc.odbc.JdbcOdbcDriver”);
Connection con = DriverMadoeer.getConnection(“jdbc:odbc:doe”,”system”,”jhon”);
Statement st = con.createStatement(ResultSet.TYPE_SCROLL_SENSEITIVE,ResultSet.CONCUR_UPDATABLE);
ResultSet rs = st.executeQuery(“select * from emp1”);
rs.absolute(3);
float newsal = rs.getFloat(3)+500;
rs.updateFloat(3,newsal);
rs.updateRow();
                         }
              }

27:what is meant by ResultSetMetaData ?How to get The ResultSet metadata of a ResultSet object?

Data about the data is called as Metadata. Similarily data about the data available in ResultSet object called as “ResultSet Metadata”.

• ResultSet Metadata includes the number of columns of a table in ResultSet object, all the column names, column datatypes and the column display sizes.
• To get the ResultSet Metadata object we will use the following method from ResultSet object.

public ResultSetMetaData getMetaData()

• To get the number of columns available in ResultSet object we will use the following method from ResultSetMetaData object.

public int getColumnCount()

• To get the name of a particular column, we will use the following method.

public String getColumnName(int fieldno)

• To get the column datatype of a particular column, we will use the following method

public String getColumnTypeName(int fieldno)

• To get the column display size of a particular column we will use the following method.

public int getColumnDisplaySize(int fieldno)

The following example demonstrates how to get ResultSetMetaData from a ResultSet object

import java.sql.*;
public class ResultSetMD
{
            public static void main(String[] args)throws Exception
            {
                        Class.forName(“sun.jdbc.odbc.JdbcOdbcDriver”);
Connection con = DriverMadoeer.getConnection(“jdbc:odbc:doe”,”system”,”jhon”);
Statement st = con.createStatement();
ResultSet rs = st.executeQuery(“select * from emp1”);
ResultSetMetaData rsmd = rs.getMetaData();
int count = rsmd.getColumnCount();
System.out.println(“number of columns......”+count);
for(int i=1;i<=count;i++)
{
System.out.println(rsmd.getColumnName(i)+”  “+rsmd.getColumnTypeName(i)+”  “+rsmd.getColumnDisplaySize(i));
System.out.println()
                                    }
                        }
            }