JDBC – Java Database Connectivity

JDBC – J ava D ata b ase C onnectivity Modified slides from Dr. Yehoshua Sagiv

Introduction to JDBC ,[object Object],[object Object],[object Object],[object Object]

JDBC Architecture Java Application JDBC Oracle DB2 MySQL Oracle Driver DB2 Driver MySQL Driver Network We will use this one…

JDBC Architecture (cont.) ,[object Object],[object Object],[object Object],[object Object],[object Object],Application JDBC Driver

JDBC Driver for Oracle ,[object Object],[object Object]

Seven Steps ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Loading the Driver ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

An Example ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],imaginary1 imaginary2 Registered Drivers MySQL

Connecting to the Database ,[object Object],[object Object],[object Object]

Connecting to the Database ,[object Object],[object Object],imaginary1 imaginary2 Registered Drivers Oracle    acceptsURL( "jdbc:imaginaryDB1" )? ,[object Object]

Interaction with the Database ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Querying with Statement ,[object Object],[object Object],String queryStr = "SELECT * FROM employee " + "WHERE lname = ‘Wong'" ; Statement stmt = con.createStatement(); ResultSet rs = stmt.executeQuery( queryStr );

Changing DB with Statement String deleteStr = "DELETE FROM employee " + "WHERE lname = ‘Wong'" ; Statement stmt = con.createStatement(); int delnum = stmt.executeUpdate( deleteStr ); ,[object Object],[object Object]

About Prepared Statements ,[object Object],[object Object],[object Object],[object Object],[object Object]

Querying with PreparedStatement String queryStr = "SELECT * FROM employee " + "WHERE superssn= ? and salary > ? " ; PreparedStatement pstmt = con.prepareStatement( queryStr ); pstmt.setString( 1 , "333445555" ); pstmt.setInt( 2 , 26000); ResultSet rs = pstmt.executeQuery();

Updating with PreparedStatement String deleteStr = “ DELETE FROM employee " + "WHERE superssn = ? and salary > ?" ; PreparedStatement pstmt = con.prepareStatement(deleteStr); pstmt.setString(1, "333445555" ); pstmt.setDouble(2, 26000); int delnum = pstmt.executeUpdate();

Statements vs. PreparedStatements: Be Careful! ,[object Object],String val = "abc" ; PreparedStatement pstmt = con.prepareStatement( "select * from R where A=?" ); pstmt.setString(1, val ); ResultSet rs = pstmt.executeQuery(); String val = "abc" ; Statement stmt = con.createStatement( ); ResultSet rs = stmt.executeQuery( "select * from R where A=" + val);

Statements vs. PreparedStatements: Be Careful! ,[object Object],[object Object],PreparedStatement pstmt = con.prepareStatement( "select * from ?" ); pstmt.setString(1, myFavoriteTableString);

Timeout ,[object Object],[object Object],[object Object]

ResultSet ,[object Object],[object Object],[object Object],[object Object],[object Object]

ResultSet Methods ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

ResultSet Methods ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

ResultSet Methods ,[object Object]

ResultSet Example Statement stmt = con.createStatement(); ResultSet rs = stmt. executeQuery( "select lname,salary from employees" ); // Print the result while ( rs .next()) { System.out.print(rs.getString(1) + ":" ); System.out.println(rs.getDouble( “salary" )); }

Mapping Java Types to SQL Types ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Null Values ,[object Object],[object Object],[object Object],[object Object],[object Object]

Null Values ,[object Object],[object Object],[object Object]

ResultSet Meta-Data ResultSetMetaData rsmd = rs.getMetaData(); int numcols = rsmd .getColumnCount(); for (int i = 1 ; i <= numcols ; i++) { System.out.print( rsmd .getColumnLabel(i)+ " " ); } A ResultSetMetaData is an object that can be used to get information about the properties of the columns in a ResultSet object An example: write the columns of the result set

Database Time ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Cleaning Up After Yourself ,[object Object],con.close(); stmt.close(); pstmt.close(); rs.close()

Dealing With Exceptions ,[object Object],catch (SQLException e) { while (e != null) { System.out.println(e.getSQLState()); System.out.println(e.getMessage()); System.out.println(e.getErrorCode()); e = e.getNextException(); } }

Transactions and JDBC ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Example ,[object Object],PreparedStatement pstmt = con.prepareStatement( "update BankAccount set amount = amount + ? where accountId = ?" ); pstmt.setInt(1,-100); pstmt.setInt(2, 13); pstmt.executeUpdate(); pstmt.setInt(1, 100); pstmt.setInt(2, 72); pstmt.executeUpdate(); What happens if this update fails?

Transaction Management ,[object Object],[object Object],[object Object],[object Object],[object Object]

AutoCommit ,[object Object],[object Object],[object Object],setAutoCommit( boolean val )

Scrollable ResultSet ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Scrollable ResultSet (cont’d) ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Scrollable ResultSet (cont’d) ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

JDBC Usage in Industry ,[object Object],[object Object],[object Object],[object Object],[object Object]

JDBC – Java Database Connectivity

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