Jdbc连接数据库Column 'EmployeeId' cannot be null

一直出现以下错误：com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Column 'EmployeeId' cannot be null

因为题目要求主键自增，类型是varchar，所以我用了触发器进行自增
begin
set new.employeeid=concat('E',lpad(((select substring(employeeid,2,3) from epoint_employee where employeeid=(select employeeid from epoint_employee order by employeeid desc limit 1))+1),3,0));
end

以下是java代码：
Test
Employee
EmployeeImpl

import java.sql.SQLException;

public class Test {
public static void main(String[] args) throws SQLException {
// TODO Auto-generated method stub
EmployeeImpl ei=new EmployeeImpl();
System.out.println(ei.save("E001", "123", "SWEET", 22, 4325));
// System.out.println(ei.save("E002", "321", "TINA", 21, 4000));
// System.out.println(ei.save("E003", "111", "JACK", 21, 4000));
// System.out.println(ei.save("E004", "222", "MARK", 21, 4000));
// System.out.println(ei.save("E005", "123", "NICK", 22, 4325));
// System.out.println(ei.delete("004"));

// System.out.println(ei.update("001", "22222", "ZS", 22, 4325));

// ei.find("001");
}
}

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

public class EmployeeImpl implements Employee {
public static String driver = "com.mysql.jdbc.Driver";
public static String url = "jdbc:mysql://localhost:3306/epoint?characterEncoding=utf8&useSSL=true";
public static String user = "sa";
public static String pwd = "11111";

public String EmployeeId;// 员工账号
public String Password; // 员工密码
public String Name; // 姓名
public int Age; // 年龄
public double Salary; // 工资

public Connection getConnection() {
    Connection con = null;
    try {
        Class.forName(driver);
        con = DriverManager.getConnection(url, user, pwd);
    } catch (Exception e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    return con;
}

public boolean save(String employeeid, String password, String name, int age, double salary){

    Connection con = new EmployeeImpl().getConnection();
    PreparedStatement pst=null;

// boolean b=true;
try {
pst=con.prepareStatement("insert into Epoint_EMPLOYEE(EmployeeId,Password,Name,Age,Salary) values(?,?,?,?,?)");//?: 占位符
//占位符有几个就写几个，否则会报错
pst.setString(1, employeeid);
pst.setString(2, password);
pst.setString(3, name);
pst.setInt(4, age);
pst.setDouble(5, salary);
// b=pst.execute();//返回Boolean类型，false表示执行CUD语句，true为R
int i=pst.executeUpdate();//返回受影响的行数
System.out.println(i);
// System.out.println(pst.getUpdateCount());//打印了几行
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return true;
}

public boolean update(String employeeid, String password, String name, int age, double salary){
    Connection con = new EmployeeImpl().getConnection();
    PreparedStatement pst=null;
    boolean b=true;
    try {
        pst=con.prepareStatement("update Epoint_EMPLOYEE set password=? where employeeid=?");//?: 占位符
        //占位符有几个就写几个，否则会报错

        pst.setString(1, password);
        pst.setString(2, employeeid);
        b=pst.execute();//返回Boolean类型，false表示执行CUD语句，true为R

// int i=pst.executeUpdate();//返回受影响的行数
// System.out.println(i);
// System.out.println(pst.getUpdateCount());//打印了几行
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

    return b;
}

public boolean delete(String employeeid) {

    Connection con = new EmployeeImpl().getConnection();
    PreparedStatement pst=null;
    boolean b=true;
    try {
        pst=con.prepareStatement("delete from Epoint_EMPLOYEE where employeeid=?");
        //占位符有几个就写几个，否则会报错
        pst.setString(1, employeeid);
        b=pst.execute();//返回Boolean类型，false表示执行CUD语句，true为R

// int i=pst.executeUpdate();//返回受影响的行数
// System.out.println(i);
// System.out.println(pst.getUpdateCount());//打印了几行
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

    return b;

}

public void find(String employeeid){
    Connection con = new EmployeeImpl().getConnection();
    ResultSet rs = null;
    PreparedStatement pst=null;
    try {
        pst=con.prepareStatement("select * from Epoint_EMPLOYEE where employeeid=?");
        //占位符有几个就写几个，否则会报错
        pst.setString(1, employeeid);
        rs = pst.executeQuery();
        while (rs.next()) {
            System.out.println(rs.getString(1));
            System.out.println(rs.getString(2));
            System.out.println(rs.getString(3));
            System.out.println(rs.getInt(4));
            System.out.println(rs.getDouble(5));
        }
    } catch (SQLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } finally {
        try {
            if (rs != null && !rs.isClosed()) {
                rs.close();
            }
            if (pst != null && !pst.isClosed()) {
                pst.close();
            }
            if (con != null && !con.isClosed()) {
                con.close();
            }

        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }
}

}

import java.sql.SQLException;

public interface Employee {
public boolean save(String employeeid, String password,String name, int age, double salary);

public boolean update(String employeeid, String password,String name, int age, double salary);
public boolean delete(String employeeid);
public void find (String employeeid);
}

是不是你在update时，给这个字段赋了空值

应该是在修改这块的空值

update时，空值

执行update时候给了空值

我把触发器的代码去掉了，运行了一遍可以的，然后再把触发器代码加上去运行，也可以了。。。自增效果也出来了。。。见鬼了。。。

设置数据库字段属性,设为可以为null就行了!

修改下你数据库字段，或者你的UPDATA做好检查

这个是事务顺序的问题吧，触发没用过，不能做回答

应该是主键冲突导致问题报错,可以每次自增的时候将id属性增加UUIDUtils的方式实现主键自增,这样既实现主键自增,又避免主键冲突!

应该是数据库表里字段属性的问题