java - servlet向MySQL插入数据，Int可以成功，String无法插入
下面是报出的错误，百度之后我已经删除了对应表的外键和约束，重启了服务器，还是无法插入。java.sql.SQLException: Duplicate key or integrity constraint violation message from server: "Column 'CourlerTitle' cannot be null"
servlet中的相应代码
`String sql = "insert into t_courler(CourlerId,CourlerTitle,UserId,CourlerContent) values(?,?,?,?)";
//String sql = "insert into t_courler(CourlerId,UserId) values(?,?)";
// 获取PreparedStatement
PreparedStatement ps = conn.prepareStatement(sql);
// 对SQL语句中的第1个参数赋值
ps.setInt(1, book.getCourierId());
ps.setString(2, book.getCourierTitle());
ps.setInt(3, book.getUserId());
ps.setString(4, book.getCourierContent());
// 执行更新操作，返回所影响的行数
int row = ps.executeUpdate();
// 判断是否更新成功
if (row > 0) {
// 更新成输出信息
System.out.print("成功添加了 " + row + "条数据！");
}
// 关闭PreparedStatement，释放资源
ps.close();
// 关闭Connection，释放资源
conn.close(); `
对应的javabean代码
package com.fz.bean;
public class courierData {
public int getCourierId() {
return CourierId;
}
public void setCourierId(int courierId) {
this.CourierId = courierId;
}
public String getCourierTitle() {
return CourierTitle;
}
public void setCourierTitle(String courierTitle) {
this.CourierTitle = courierTitle;
}
public String getCourierContent() {
return CourierContent;
}
public void setCourierContent(String courierContent) {
this.CourierContent = courierContent;
}
public int getUserId() {
return UserId;
}
public void setUserId(int userId) {
this.UserId = userId;
}
public String getCourierImage() {
return CourierImage;
}
public void setCourierImage(String courierImage) {
this.CourierImage = courierImage;
}
public float getCourierMoney() {
return CourierMoney;
}
public void setCourierMoney(float courierMoney) {
this.CourierMoney = courierMoney;
}
public String getCourierDate() {
return CourierDate;
}
public void setCourierDate(String courierDate) {
this.CourierDate = courierDate;
}
public int getOrderId() {
return OrderId;
}
public void setOrderId(int orderId) {
this.OrderId = orderId;
}
public String getCourierWeight() {
return CourierWeight;
}
public void setCourierWeight(String courierWeight) {
CourierWeight = courierWeight;
}
private int CourierId; //快递信息id
private String CourierTitle; //快递标题
private String CourierContent; //快递内容
private int UserId; //发布人id
private String CourierImage; //快递图片
private float CourierMoney; //快递悬赏
private String CourierDate; //快递发布日期
private int OrderId; //接单人
private String CourierWeight; //快递重量
}请求的jsp页面相应代码
<form action="courierServlet?method=update" method="post" onsubmit="check(this)">
<table align="center" width="450">
<tr>
<td align="center" colspan="2">
<h2>添加图书信息</h2>
<hr>
</td>
</tr>
<tr>
<td align="right">快递ID：</td>
<td><input type="text" name="courierId"></td>
</tr>
<tr>
<td align="right">title：</td>
<td><input type="text" name="courierTitle"></td>
</tr>
<tr>
<td align="right">用户ID：</td>
<td><input type="text" name="userId" /></td>
</tr>
<tr>
<td align="right">content：</td>
<td><input type="text" name="courierContent" /></td>
</tr>
<tr>
<td align="center" colspan="2"><input type="submit" value="添 加">
</td>
</tr>
</table>
</form> 下图是对应表中的相应字段
