Java uses jdbc to connect to a database instance

Connect to sqlserver Database

Package jdbc; import java. SQL. connection; import java. SQL. driver; import java. SQL. driverManager; import java. SQL. preparedStatement; import java. SQL. resultSet; import java. SQL. SQLException; public class JdbcTest1 {/*** @ param args */public static void main (String [] args) {// TODO Auto-generated method stubString className = "com. microsoft. sqlserver. jdbc. SQLServerDriver "; // load the jdbc driver, Class. forName () Load try {Cl Ass. forName (className); // 11111111111111} catch (ClassNotFoundException e) {e. printStackTrace ();} Driver driver = null; // register the jdbc Driver and register it in the DriverManager class. registerDriver (driver) try {Driver = new com. microsoft. sqlserver. jdbc. SQLServerDriver (); /// // DriverManager. registerDriver (driver ); /// // 222222222222} catch (SQLEx Ception e) {// TODO Auto-generated catch blocke. printStackTrace ();} // 3 create a database Connection object. DriverManager establishes a Connection object and knows which database to connect to, Connection username and password Connection con = null; String url = "jdbc: sqlserver: // localhost: 1433; DatabaseName = db "; // jdbc url. The identification methods for different databases are different. String user = "sa"; String password = "123456"; try {con = DriverManager. getConnection (url, user, password ); /// //} catch (Exception e) {e. printStackTrace ();} // PreparedStatementPreparedStatement pstmt = null; String SQL = "select * from book where price
 ? "; Try {pstmt = con. prepareStatement (SQL); //} catch (SQLException e) {// TODO Auto-generated catch blocke. printStackTrace ();} try {pstmt. setFloat (1, (float) 50.0); pstmt. setInt (2, 5);} catch (SQLException e) {e. printStackTrace ();} // execute the database SQL operation ResultSet rs = null using the statement object; try {rs = pstmt.exe cuteQuery (); ////////////////////////////////////////} catch (SQLException e) {// TODO Au To-generated catch blocke. printStackTrace ();} // process the database query result try {while (rs. next () {String isbn = rs. getString (1); String author = rs. getString ("author"); Float price = rs. getFloat ("price"); Integer number = rs. getInt ("number"); System. out. println ("isbn:" + isbn + "\ nauthor:" + author + "\ ntotal:" + price * number + "\ n");} catch (SQLException e) {e. printStackTrace ();} // close the resource. The order is the opposite: try {if (rs! = Null) {rs. close () ;}if (pstmt! = Null) {pstmt. close ();} if (con! = Null) {con. close () ;}} catch (SQLException e) {e. printStackTrace ();}}}

Connect to the mysql database

Package jdbc; import java. SQL. connection; import java. SQL. driver; import java. SQL. driverManager; import java. SQL. preparedStatement; import java. SQL. resultSet; import java. SQL. SQLException; import java. SQL. statement; public class JdbcTest {/** query the content in the database table, and display * @ param args */public static void main (String [] args) in the console output) {String className = "com. mysql. jdbc. driver "; // load the jdbc Driver, Class. forName () Load try {Class. forName (ClassName); // 11111111111111} catch (ClassNotFoundException e) {e. printStackTrace ();} Driver driver = null; // register the jdbc Driver and register it in the DriverManager class. registerDriver (driver) try {Driver = new com. mysql. jdbc. driver (); /// // DriverManager. registerDriver (driver ); /// // 222222222222} catch (SQLException e) // TODO Auto-generated c Atch blocke. printStackTrace ();} // 3 create a database Connection object. DriverManager establishes a Connection object and knows which database to connect to, Connection username and password Connection con = null; String url = "jdbc: mysql: // localhost: 3306/db "; // jdbc url. The identification methods for different databases are different. String user = "root"; String password = "123456"; try {con = DriverManager. getConnection (url, user, password ); /// //} catch (Exception e) {e. printStackTrace ();} // 4... prepare the work before operating the database. You can use Statement or PreparedStatement to operate the database. You can use the Connection object to obtain the Statement object // Statement stmt = null; try {stmt = con. createStatement (); //} catch (SQLException e) {e. printStackTrace ();}/** PreparedStatementPreparedStatement pstmt = null; String SQL = "select * from book where price
 ? "; Try {pstmt = con. prepareStatement (SQL); //} catch (SQLException e) {// TODO Auto-generated catch blocke. printStackTrace ();} try {pstmt. setFloat (1, (float) 50.0); pstmt. setInt (2, 5);} catch (SQLException e) {e. printStackTrace ();} ** // execute the database SQL operation String SQL = "select * from book where price <50 and number> 5" by using the statement object "; resultSet rs = null; try {rs = stmt.exe cuteQuery (SQL );//////// //// //} Catch (SQLException e) {// TODO Auto-generated catch blocke. printStackTrace ();} // process the database query result try {while (rs. next () {String isbn = rs. getString (1); String author = rs. getString ("author"); Float price = rs. getFloat ("price"); Integer number = rs. getInt ("number"); System. out. println ("isbn:" + isbn + "\ nauthor:" + author + "\ ntotal:" + price * number + "\ n");} catch (SQLException e) {e. pr IntStackTrace () ;}/// close the resource. The order is the opposite: try {if (rs! = Null) {rs. close () ;}if (stmt! = Null) {stmt. close () ;}if (con! = Null) {con. close () ;}} catch (SQLException e) {e. printStackTrace ();}}}