Q) explain about “char” data type in java?

Character data type in java supports Unicode character set. A “char” type variable occupies 2 bytes to memory. It is meant for supporting internationalization. i.e., any language characters in the world can be accommodated.

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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 : " ); ...

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.

Q) What is the purpose of JDBC?

A) -> Java application can do any task by making a method (function) call. ->java method calls are not understandable to database management system. They can understand only SQL statements. ->SQL statements can’t be directly used in a java application. Java compiler complains. ->therefore, we say that java environment and database environment are heterogeneous to each other. Purpose of JDBC: ->for any kind of java application to communicate with any kind of database (management system) in a standard manner, JDBC is used.

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