java鏈接數據庫，實現增刪改查操做

一.前言

寫這個文章的緣由是爲了鞏固本身鏈接數據庫步驟
但願對初次學習數據庫的朋友有所幫助

二.MySQL數據庫鏈接

數據庫鏈接步驟加載驅動程序，獲取數據庫鏈接對象

2.1驅動jar包

• 點我下載

2.2代碼

package cn.sg.xx.test;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class Main {
    public static void main(String[] args) throws SQLException, ClassNotFoundException {
        try {
            //數據庫驅動參數
            String Driver = "com.mysql.cj.jdbc.Driver";//"com.mysql.jdbc.Driver"-->驅動地址已通過時
            //鏈接的URL,數據庫名爲test
            String URL = "jdbc:mysql://localhost:3306/test?serverTimezone=UTC&characterEncoding=utf8";//後邊的參數serverTimezone-->指定時區，characterEncoding-->編碼格式
            //數據庫用戶名
            String Username = "root";
            //數據庫密碼
            String Password = "123";
            //加載MySQL驅動程序
            Class.forName(Driver);
            //與MySQL數據庫創立鏈接
            Connection con = null;
            con = DriverManager.getConnection(URL, Username, Password);

        } catch (ClassNotFoundException e) {
            System.out.println("驅動程序沒有找到！");
        } catch (SQLException e) {
            System.out.println("SQL異常！");
        }
    }
}

三.增長表數據

String sql = "INSERT INTO test(id,NAME,sex) VALUES(?,?,?);";
建議寫成這種語法，指定插入的列，能夠防止表字段修改後，程序報錯
使用PreparedStatement 進行sql語句的裝配，能夠防止sql注入

3.1代碼

package cn.sg.xx.test;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;

public class Main {
    public static void main(String[] args) {
        try {
            //數據庫驅動參數
            String Driver = "com.mysql.cj.jdbc.Driver";//"com.mysql.jdbc.Driver"-->驅動地址已通過時
            //鏈接的URL,數據庫名爲test
            String URL = "jdbc:mysql://localhost:3306/test?serverTimezone=UTC&characterEncoding=utf8";//後邊的參數serverTimezone-->指定時區，characterEncoding-->編碼格式
            //數據庫用戶名
            String Username = "root";
            //數據庫密碼
            String Password = "123";
            //加載MySQL驅動程序
            Class.forName(Driver);
            //與MySQL數據庫創立鏈接
            Connection con = null;
            con = DriverManager.getConnection(URL, Username, Password);

            //sql語句裝配,？爲佔位符
            String sql = "INSERT INTO test(id,NAME,sex) VALUES(?,?,?);";
            PreparedStatement stmt = con.prepareStatement(sql);
            stmt.setInt(1, 2);
            stmt.setString(2, "張三");
            stmt.setString(3, "男");
            stmt.executeUpdate();

            //執行完數據庫的操做有指令以後要釋放資源，不然會致使內存的溢出
            stmt.close();
            con.close();

        } catch (ClassNotFoundException e) {
            System.out.println("驅動程序沒有找到！");
        } catch (SQLException e) {
            System.out.println("SQL異常！");
        }

    }
}

四.刪除表數據

刪除表數據的操做和插入操做基本相同，只有sql語句不一樣

4.1代碼

String sql = "DELETE FROM test WHERE id = 1";
PreparedStatement stmt = con.prepareStatement(sql);
stmt.executeUpdate();

五.修改表數據

同插入數據同樣，僅僅修改sql語句爲
UPDATE test SET sex = '女' WHERE id = 1

六.查找表數據

表數據的查找須要比上邊的插入、刪除操做多關閉ResoultSet資源
ResoultSet rs;
rs.close();

6.1代碼

//查找表數據
            String sql = "SELECT * FROM test";
            PreparedStatement stmt = con.prepareStatement(sql);
            ResultSet rs = stmt.executeQuery();
            //從 rs 獲取數據
            while (rs.next()) {
                //rs.getMetaData().getColumnCount() --> 獲取表的列數
                for (int i = 1; i <= rs.getMetaData().getColumnCount(); i++) {
                    String colunmName = rs.getMetaData().getColumnName(i);//獲取列名
                    Object temp = rs.getString(i);//獲取該列對應元素的值
                    System.out.print(colunmName + "-->" + temp + "\t");
                }
                System.out.println();

---

七.所有代碼

package cn.sg.xx.test;

import java.sql.*;

public class Main {
    public static void main(String[] args) throws SQLException {
        Connection con = null;
        PreparedStatement stmt = null;
        ResultSet rs = null;
        try {
            //數據庫驅動參數
            String Driver = "com.mysql.cj.jdbc.Driver";//"com.mysql.jdbc.Driver"-->驅動地址已通過時
            //鏈接的URL,數據庫名爲test
            String URL = "jdbc:mysql://localhost:3306/test?serverTimezone=UTC&characterEncoding=utf8";//後邊的參數serverTimezone-->指定時區，characterEncoding-->編碼格式
            //數據庫用戶名
            String Username = "root";
            //數據庫密碼
            String Password = "123";
            //加載MySQL驅動程序
            Class.forName(Driver);
            //與MySQL數據庫創立鏈接
            con = DriverManager.getConnection(URL, Username, Password);

            //sql語句裝配,？爲佔位符
            String sql = "INSERT INTO test(id,NAME,sex) VALUES(?,?,?);";
            stmt = con.prepareStatement(sql);
            stmt.setInt(1, 2);
            stmt.setString(2, "張三");
            stmt.setString(3, "男");
            stmt.executeUpdate();

            //刪除表數據
            sql = "DELETE FROM test WHERE id = 1";
            stmt = con.prepareStatement(sql);
            stmt.executeUpdate();

            //修改表數據
            sql = "UPDATE test SET sex = '女' WHERE id = 1";
            stmt = con.prepareStatement(sql);
            stmt.executeUpdate();

            //查找表數據
            sql = "SELECT * FROM test";
            stmt = con.prepareStatement(sql);
            rs = stmt.executeQuery();
            //從 rs 獲取數據
            while (rs.next()) {
                //rs.getMetaData().getColumnCount() --> 獲取表的列數
                for (int i = 1; i <= rs.getMetaData().getColumnCount(); i++) {
                    String colunmName = rs.getMetaData().getColumnName(i);//獲取列名
                    Object temp = rs.getString(i);//獲取該列對應元素的值
                    System.out.print(colunmName + "-->" + temp + "\t");
                }
                System.out.println();
            }
            //執行完數據庫的操做有指令以後要釋放資源，不然會致使內存的溢出

        } catch (ClassNotFoundException e) {
            System.out.println("驅動程序沒有找到！");
        } catch (SQLException e) {
            System.out.println("SQL異常！");
        } finally {
            //關閉資源
            if (rs != null)
                rs.close();
            if (stmt != null)
                stmt.close();
            if (con != null)
                con.close();

        }

    }
}