Skip to main content

Q) Explain the architecture of ResultSet?



A)
->A Resultset is divided into 3 parts.

1) Zero record area
2) Records area
3) No record area

->when the resultSet is open a logical pointer known as “cursor” points to zero record area.
->when cursor is pointing to zero record or no record area we should not process the record.     We get SQL Exception.
->java.sql.ResultSet object has around 15 methods to deal with cursor.
->next() method is most frequently used method.
->when next() method is called on ResultSet object, 2 things happen in the background.
  1) Cursor is moved in forward direction by one record area.
  2) It returns true if record exists there otherwise false.
->To process the record, i.e. to retrieve the record each column value of the record (row) of the ResultSet object, getxxx() methods are available. These methods take column member in the ResultSet records as argument and return the column value. Relational table column type influences the kind of getxxx method we need to call on ResultSet object.

Some example for getxxx() methods :
getFloat()
getString()
getInt()
getBytes()

Comments

Post a Comment

Popular posts from this blog

Q) Retrieving data from database?

A)   ->to retrieve the data from database we need to submit SELECT statement from JDBC application. -> executeQuery() method of statement object is used for this purpose. This method has the fallowing ResultSet executeQuery(String sql) throws SQLException Ex: ResultSet rs = st.executeQuery(“SELECT * FROM ACCOUNT”); ->objectoriented representation of tables formate data is called ResultSet object. Ao the driver created one object i.e. ResultSet object. ->object orientation representation of a table of records returned from db is nothing but “ ResultSet ” object.  
Post a Comment
Read more

Q) Explain repeated deletion of records.

A) //RepeatedDeletion.java import java.util.Scanner; import java.sql.*; class RepeatedDeletion {        public static void main(String[] args) {               Connection con= DriverManager. getConnection ( "jdbc:odbc:prince" , "scott" , "tiger" );               PreparedStatement ps=con.PreparedStatement( "DELETE FROM ACCOUNT WHERE ACCNO=?" );               Scanner s= new Scanner(System. in );               while ( true )               {                      System. out .println( "Enter accno : " );      ...
Post a Comment
Read more

Q) What is JDBC driver? What is its role in java database connection?

A) ->A translation software written in java according o JDBC specification is nothing but “JDBC driver”. -> JDBC driver implements JDBC API. Use single API. JDBC driver role: They are 4 roles   1)       Establishing connection between JDBC client and database server. 2)       Receiving JDBC method calls made by JDBC client while performing database (CRUD) operations. 3)       Translating java method calls into DBMS understandable calls and forwarding them to database server. 4)       Receiving the results from database server. Translating them into java format and handling over the same to the JDBC client.
Post a Comment
Read more