Java自学-JDBC 增、删、改

时间 2020-05-08

标签 java 自学 jdbc 栏目 Java 繁體版

原文原文链接

JDBC 增、删、改

CRUD是最多见的数据库操做，即增删改查 C 增长(Create) R 读取查询(Retrieve) U 更新(Update) D 删除(Delete)html

在JDBC中增长，删除，修改的操做都很相似，只是传递不一样的SQL语句就好了。java

步骤 1 : 增长mysql

这段代码就是Hello JDBC中的代码，用于向数据库中插入数据sql

package jdbc;
   
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;
   
public class TestJDBC {
    public static void main(String[] args) {
   
        try {
            Class.forName("com.mysql.jdbc.Driver");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
   
        try (
            Connection c = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/how2java?characterEncoding=UTF-8",
                "root", "admin");
            Statement s = c.createStatement();             
        )
        {
            String sql = "insert into hero values(null," + "'提莫'" + "," + 313.0f + "," + 50 + ")";
            s.execute(sql);
               
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}

步骤 2 : 删除数据库

删除和增长很相似，只不过是执行的SQL语句不同罢了spa

package jdbc;
   
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;
   
public class TestJDBC {
    public static void main(String[] args) {
   
        try {
            Class.forName("com.mysql.jdbc.Driver");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
   
        try (
            Connection c = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/how2java?characterEncoding=UTF-8",
                "root", "admin");
            Statement s = c.createStatement();             
        )
        {
            String sql = "delete from hero where id = 5";
            s.execute(sql);
               
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}

步骤 3 : 修改设计

修改也同样，执行另外一条SQL语句就能够了code

package jdbc;
   
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;
   
public class TestJDBC {
    public static void main(String[] args) {
   
        try {
            Class.forName("com.mysql.jdbc.Driver");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
   
        try (
            Connection c = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/how2java?characterEncoding=UTF-8",
                "root", "admin");
            Statement s = c.createStatement();             
        )
        {
            String sql = "update hero set name = 'name 5' where id = 3";
            s.execute(sql);
               
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}

练习：增、删、改htm

设计一个方法get

public static void execute(String sql)

方法接受的参数是SQL语句，不管是增长，删除，仍是修改，都调用这个方法，每次传不一样的SQL语句做为参数

答案 :

package jdbc;
 
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;
 
public class TestJDBC {
 
    public static void execute(String sql) {
        try {
            Class.forName("com.mysql.jdbc.Driver");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
 
        try (Connection c = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/how2java?characterEncoding=UTF-8",
                "root", "admin"); Statement s = c.createStatement();) {
 
            s.execute(sql);
 
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
 
    public static void main(String[] args) {
        execute("delete from hero where id = 1");
    }
}