4.27.txt

java学习的点滴

及联表的删除

方法：先删除从表的相关数据，再删除主表的相关数据。
__________________________________________________________________________

用java语言来实现:
-------------------------------------------------------
/*实现数据库的连接*/
package conn;

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

public class DBConn {

	public static Connection getDBConn()
	{
		Connection conn=null;
		try {
			Class.forName("oracle.jdbc.driver.OracleDriver");
			conn=DriverManager.getConnection("jdbl:oracle:thin:@127.0.0.1:1521:dbl","scott","tiger");
		} catch (Exception e) {
			// TODO 自动生成 catch 块
			System.out.println("数据库连接失败");
			e.printStackTrace();
		}
		return conn;
	}
}

------------------------------------------------------------

/*实现及联表的删除*/
package dao;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import vo.CongBiaoVO;
import vo.ZhuBiaoVO;
import conn.DBConn;

public class JLCaoZuo {

	/*删除从表的相关数据*/
	public int deleteFK(int zid,Connection conn) throws Exception{
		
		Statement st=null;
		
		int flg=0;
		String sql=" delete congbiao where zid="+zid+" ";
		
		
		st=conn.createStatement();
		flg=st.executeUpdate(sql);
		
		return flg;
		
	}
	
	/*删除主表的相关数据*/
	public int deletePK(int zid){
		
		Connection conn=null;
		Statement st=null;
		
		int flg1=0;
		int flg2=0;
		
		String sql="delete zhubiao where zid ="+zid + " ";
		
		try {
			conn=DBConn.getDBConn();
			conn.setAutoCommit(false);
			flg1=deleteFK(zid,conn);
			
			st=conn.createStatement();
			flg2=st.executeUpdate(sql);
			conn.commit();
		} catch (Exception e) {
			// TODO 自动生成 catch 块
			try {
				conn.rollback();
			} catch (SQLException e1) {
				// TODO 自动生成 catch 块
				e1.printStackTrace();
			}
			System.out.println("删除主表失败");
			e.printStackTrace();
		}finally{
			if(flg1==0){System.out.println("删除从表失败");}
			try {
				conn.setAutoCommit(true);
			} catch (SQLException e) {
				// TODO 自动生成 catch 块
				e.printStackTrace();
			}
			try {
				st.close();
			} catch (SQLException e) {
				// TODO 自动生成 catch 块
				e.printStackTrace();
			}
			try {
				conn.close();
			} catch (SQLException e) {
				// TODO 自动生成 catch 块
				e.printStackTrace();
			}
		}
		
		return flg2;
	}
	
}


----------------------------------------------------

/*判断删除是否成功*/
package bo;

import vo.CongBiaoVO;
import vo.ZhuBiaoVO;
import dao.JLCaoZuo;
public class Business {
	
	
	
	public int diaplayDeletePK(int zid){
		JLCaoZuo jl1=new JLCaoZuo();
		int i=jl1.deletePK(zid);
		if(i!=0){
			System.out.println("删除成功");
		}else{
			System.out.println("删除失败");
			
		}
		return i;
	}
}


-------------------------------------------

/*测试类*/


package test;

import vo.CongBiaoVO;
import vo.ZhuBiaoVO;
import bo.Business;

public class Test {
	public static void main(String [] a){
		Business b1=new Business();
		
		b1.diaplayDeletePK(9);
	}

}