JDBC 数据库连接

三个类：

Connection、Statement(PreparedStatement)、ResultSet 

        Connection conn = null ;
        Statement stm = null ;
        ResultSet res = null ;
        String sql = " select * from table1 " ;
        try{
            Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
            conn = DriverManager.getConnection(conPro.get("jdbc:sqlserver://localhost:1433; DatabaseName=20170706_TestDb"),conPro.get("sa"),conPro.get("123456"));
            stm = conn.createStatement() ; 
            res = stm.executeQuery(sql);
            while(res.next()){
                System.out.println(res.getString("Contract_code")+"	"+res.getString("Contract_name")+"	"+res.getFloat("Contract_money"));
            }
        }catch(Exception e){
            e.printStackTrace();
        }finally{
            try{
                if(res!=null)
                    res.close();
                if(stm!=null)
                    stm.close();
                if(conn!=null)
                    conn.close();
            }catch(SQLException e){
                e.printStackTrace();
            }
        }

使用 PreparedStatement 时，参数下标是从 1 开始的。

String mySQL = "SELECT * FROM TABLE WHERE ID=?";
conn = DriverManager.getConnection(Url, UserName, Password);
prestmt = conn.prepareStatement(mySQL);
prestmt.setString(1, "");
res = prestmt.executeQuery();