Java自学-JDBC 增、删、改

jdbc 增、删、改

crud是最常见的数据库操作，即增删改查
c 增加(create)
r 读取查询(retrieve)
u 更新(update)
d 删除(delete)

在jdbc中增加，删除，修改的操作都很类似，只是传递不同的sql语句就行了。

步骤 1 : 增加

这段代码就是hello jdbc中的代码，用于向数据库中插入数据

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

删除和增加很类似，只不过是执行的sql语句不一样罢了

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

修改也一样，执行另一条sql语句就可以了

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：

设计一个方法

public static void execute(string sql)

方法接受的参数是sql语句，无论是增加，删除，还是修改，都调用这个方法，每次传不同的sql语句作为参数

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");
    }
}