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JDBC（3）-使用PreparedStatement接口实现增、删、改操作
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1、PreparedStatement接口引入
PreparedStatement是Statement的子接口，属于预处理操作，与直接使用Statement不同的是，PreparedStatement在操作时，
是先在数据表中准备好了一条SQL语句，但是此SQL语句的具体内容暂时不设置，而是之后再进行设置。
（以后开发一般使用PreparedStatement，不用Statement）
2、使用PreparedStatement接口实现添加数据操作
public class JDBCDemo5 {
private static MysqlUtil dbUtil = new MysqlUtil();
/**
* 添加emp
* @param emp
* @return
* @throws Exception
*/
private static int addEmp(Emp emp) throws Exception{
Connection conn = dbUtil.getConnection();
String sql = "insert into emp2 values(null,?,?,?)";
PreparedStatement pstmt = conn.prepareStatement(sql);
pstmt.setString(1, emp.getName());
pstmt.setDouble(2, emp.getSalary());
pstmt.setInt(3, emp.getAge());
int result = pstmt.executeUpdate();
dbUtil.close(pstmt, conn);
return result;
}
public static void main(String[] args) throws Exception {
Emp emp = new Emp("pengpeng",13000,27);
int result = addEmp(emp);
if(result==1){
System.out.println("添加成功");
}else{
System.out.println("添加失败");
}
}
}
3、使用PreparedStatement接口实现更新数据操作
public class JDBCDemo6 {
private static MysqlUtil dbUtil = new MysqlUtil();
private static int updateEmp(Emp emp) throws Exception{
Connection conn = dbUtil.getConnection();
String sql = "update emp2 set name=?,salary=?,age=? where id=?";
PreparedStatement pstmt = conn.prepareStatement(sql);
pstmt.setString(1, emp.getName());
pstmt.setDouble(2, emp.getSalary());
pstmt.setInt(3, emp.getAge());
pstmt.setInt(4, emp.getId());
int result = pstmt.executeUpdate();
dbUtil.close(pstmt, conn);
return result;
}
public static void main(String[] args) throws Exception {
Emp emp = new Emp(4,"pengpeng",13000,27);
int result = updateEmp(emp);
if(result==1){
System.out.println("update成功");
}else{
System.out.println("update失败");
}
}
}
4、使用PreparedStatement接口实现删除数据操作
public class JDBCDemo7 {
private static MysqlUtil dbUtil = new MysqlUtil();
private static int deleteEmp(int id) throws Exception{
Connection conn = dbUtil.getConnection();
String sql = "delete from emp2 where id=?";
PreparedStatement pstmt = conn.prepareStatement(sql);
pstmt.setInt(1, id);
int result = pstmt.executeUpdate();
dbUtil.close(pstmt, conn);
return result;
}
public static void main(String[] args) throws Exception{
Emp emp = new Emp(4,"pengpeng",13000,27);
int result = deleteEmp(4);
if(result==1){
System.out.println("delete成功");
}else{
System.out.println("delete失败");
}
}
}
