jsp实现JavaWeb中报错汇总

注：以下代码均贴的片段，并非完整代码。 

1

 check the manual that corresponds to your MySQL server version for the right syntax to use near 'where id=5' at line 1check the manual that corresponds to your MySQL server version for the right syntax to use near 'where id=5' at line 1

检查“where id=5”附近的代码： 

//Test
Person p = new Person(5,"李莲英","男",20,"110");

//Function
String sql = "update users set name=?, sex=?, age=?, phone=?, where id=? ";

观察到在“where”前多了个“,”，去掉即可：

String sql = "update users set name=?, sex=?, age=?, phone=? where id=? ";

2

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '?' at line 1

 检查“?”附近的代码：

//Test
public void test7(){
		Person p = dao.findByIdPerson(10);
		System.out.println(p.toString());
	}

//Function
String sql = "select * from users where id=? ";
//4.为占位符传值
		pmst.setInt(1, id);
//5.执行查询语句
		rs = pmst.executeQuery(sql);

修改为：

String sql = "select * from users where id= "+id;
//4.为占位符传值
//		pmst.setInt(1, id);
//5.执行查询语句
		rs = pmst.executeQuery(sql);

或者：

//Function
String sql = "select * from users where id=? ";
//4.为占位符传值
		pmst.setInt(1, id);
//5.执行查询语句
		rs = pmst.executeQuery();

错误原因：若用占位符方式传值，executeQuery();要无参。

添加字符串可有参，也可无参，最好是所有的都写成无参。