jdbc

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简单增删改查

package Practice170829;import org.junit.Test;import java.sql.*;/** * Created by 8102 on 2017/8/29. */public class JDBC01 {    @Test    public void queryAll(){ //查询所有        Connection conn = null;        PreparedStatement pstmt = null;        ResultSet rs = null;        try {            // 1 加载JDBC驱动            Class.forName("com.mysql.jdbc.Driver");            // 2 连接数据库            conn = DriverManager.getConnection(                    "jdbc:mysql://127.0.0.1:3306/my_test?useUnicode=true&character=utf-8",                    "root","root");            // 3 准备执行的sql对象            String sql = "SELECT * FROM users";            pstmt = conn.prepareStatement(sql);            // 4 执行sql语句,并显示结果            rs = pstmt.executeQuery();            while (rs.next()){                System.out.println(rs.getString("user_name")+":"+rs.getInt("user_age"));            }        } catch (Exception e) {            e.printStackTrace();        } finally {            // 5 关闭 先开的后关，后开的先关            try {                if(rs != null){                    rs.close();                }                if(pstmt != null){                    pstmt.close();                }                if(conn != null){                    conn.close();                }            } catch (SQLException e) {                e.printStackTrace();            }        }    }    @Test    public void queryByConditions(){    //条件查询        Connection conn = null;        PreparedStatement pstmt = null;        ResultSet rs = null;        try {            Class.forName("com.mysql.jdbc.Driver");            conn = DriverManager.getConnection(                    "jdbc:mysql://127.0.0.1:3306/my_test?useUnicode=true&character=utf-8",                    "root","root");            String sql = "SELECT * FROM users WHERE user_age>25;";            pstmt = conn.prepareStatement(sql);            rs = pstmt.executeQuery();            while (rs.next()){                System.out.println(rs.getString("user_name")+":"+rs.getInt("user_age"));            }        } catch (Exception e) {            e.printStackTrace();        } finally {            try {                if(rs != null){                    rs.close();                }                if(pstmt != null){                    pstmt.close();                }                if(conn != null){                    conn.close();                }            } catch (SQLException e) {                e.printStackTrace();            }        }    }    @Test    public void del(){  //删除        Connection conn = null;        PreparedStatement pstmt = null;        try {            Class.forName("com.mysql.jdbc.Driver");            conn = DriverManager.getConnection(                    "jdbc:mysql://127.0.0.1:3306/my_test?useUnicode=true&character=utf-8",                    "root","root");            String sql = "DELETE FROM users WHERE user_name=?";            pstmt = conn.prepareStatement(sql);            pstmt.setString(1,"wangqing");            int flag = pstmt.executeUpdate();            if(flag>0){                System.out.println("删除成功！");            } else {                System.out.println("删除失败！");            }        } catch (Exception e) {            e.printStackTrace();        } finally {            try {                if(pstmt != null){                    pstmt.close();                }                if(conn != null){                    conn.close();                }            } catch (SQLException e) {                e.printStackTrace();            }        }    }    @Test    public void update(){  //修改        Connection conn = null;        PreparedStatement pstmt = null;        try {            Class.forName("com.mysql.jdbc.Driver");            conn = DriverManager.getConnection(                    "jdbc:mysql://127.0.0.1:3306/my_test?useUnicode=true&character=utf-8",                    "root","root");            String sql = "UPDATE users SET user_age=? WHERE user_id=?";            pstmt = conn.prepareStatement(sql);            pstmt.setInt(1,0);            pstmt.setInt(2,2);            int flag = pstmt.executeUpdate();            if(flag>0){                System.out.println("修改成功！");            } else {                System.out.println("修改失败！");            }        } catch (Exception e) {            e.printStackTrace();        } finally {            try {                if(pstmt != null){                    pstmt.close();                }                if(conn != null){                    conn.close();                }            } catch (SQLException e) {                e.printStackTrace();            }        }    }    @Test    public void add(){  //增加        Connection conn = null;        PreparedStatement pstmt = null;        try {            Class.forName("com.mysql.jdbc.Driver");            conn = DriverManager.getConnection(                    "jdbc:mysql://127.0.0.1:3306/my_test?useUnicode=true&character=utf-8",                    "root","root");            String sql = "INSERT INTO login(username,pwd) VALUES(?,?)";            pstmt = conn.prepareStatement(sql);            pstmt.setString(1,"");            pstmt.setString(2,"514");            int flag = pstmt.executeUpdate();            if(flag>0){                System.out.println("增加成功！");            } else {                System.out.println("增加失败！");            }        } catch (Exception e) {            e.printStackTrace();        } finally {            try {                if(pstmt != null){                    pstmt.close();                }                if(conn != null){                    conn.close();                }            } catch (SQLException e) {                e.printStackTrace();            }        }    }}

存储过程和函数

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