java连接数据库进行增删改查

来来来，了解一下java的最基本的功能，连接数据库进行增删改查

怎么连接数据库呢？

1.要连接数据库受限得有支持链接数据库的jar包，放置的位置如下，此处是链接mysql的jar：

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注：如果想连接其他数据库，例如oracle可自行下载他的jar包然后放在同样的地方即可
2.代码展示：

'public static Connection getConn() throws ClassNotFoundException,SQLException  {
            try{
                Connection con = null;
        // 加载驱动程序
        Class.forName("com.mysql.jdbc.Driver");
        String url = "jdbc:mysql://127.0.0.1/test";//test是数据库名称
        String user = "root";//账号
        String pwd = "1234qwer";//密码
        // 建立连接
        con = DriverManager.getConnection(url, user, pwd);
         catch(Exception e){
                 e.printStackTrace();  
          }
         finally{
              con.close();
              stm.close();
              rs.close();
         }
}'

那怎么判断我这个数据库到底链接上了？

简单的方法,如下：

    try {
        Connection con = ConnectionUtil.getConn();
        System.out.println(con.isClosed());
    } catch (ClassNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (SQLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
'

结果展示为1，证明链接失败；结果展示为0，证明链接成功

向数据库添加表格

  'String sql ="create table Depart(depNo int primary key,depName varchar(50) not null,depMan varchar(50) not null) ";
    Connection con;
    int i = 0;
    try {
        con = ConnectionUtil.getConn();
        Statement st = (Statement) con.createStatement();// 创建sql执行对象
        int rs = st.executeUpdate(sql);//执行sql
        System.out.println(rs);
    } catch (ClassNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (SQLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }'

表格中插入数据

'String sql ="insert into Depart values(1,'ceshiyixia','woman')";
    Connection con;
    int i = 0;
    try {
        con = ConnectionUtil.getConn();
        Statement st = (Statement) con.createStatement();// 创建sql执行对象
        int rs = st.executeUpdate(sql);//执行sql
        System.out.println(rs);
    } catch (ClassNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (SQLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }'

表格中查询数据

'String sql ="select * from  Depart";
    Connection con;
    int i = 0;
    try {
        con = ConnectionUtil.getConn();
        Statement st = (Statement) con.createStatement();// 创建sql执行对象
        ResultSet rs = st.executeQuery(sql);//执行sql
        System.out.println(rs);
    } catch (ClassNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (SQLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }'

表格中更改字段

'String sql ="alter table Depart rename column depName to depName1";
    Connection con;
    int i = 0;
    try {
        con = ConnectionUtil.getConn();
        Statement st = (Statement) con.createStatement();// 创建sql执行对象
        int rs = st.executeUpdate(sql);//执行sql
        System.out.println(rs);
    } catch (ClassNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (SQLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }'

表格中修改数据

'String sql ="update Depart set depNo=20171020";
    Connection con;
    int i = 0;
    try {
        con = ConnectionUtil.getConn();
        Statement st = (Statement) con.createStatement();// 创建sql执行对象
        int rs = st.executeUpdate(sql);//执行sql
        System.out.println(rs);
    } catch (ClassNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (SQLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }'

表格中删除数据

'String sql ="delete from Depart where depNo=20171020 ";
    Connection con;
    int i = 0;
    try {
        con = ConnectionUtil.getConn();
        Statement st = (Statement) con.createStatement();// 创建sql执行对象
        int rs = st.executeUpdate(sql);//执行sql
        System.out.println(rs);
    } catch (ClassNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (SQLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }'

删除表格

'String sql ="drop table Depart ";
    Connection con;
    int i = 0;
    try {
        con = ConnectionUtil.getConn();
        Statement st = (Statement) con.createStatement();// 创建sql执行对象
        int rs = st.executeUpdate(sql);//执行sql
        System.out.println(rs);
    } catch (ClassNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (SQLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }'

删除数据库

想要知道代码，请听下回分解~~~其实就是sql语句的不同，看了这么多例子发现是不是都一样呀，希望对入门的你有所帮助，谢谢观看，后续会努力增加更精彩的内容！