Java org.springframework.dao.DataIntegrityViolationException:空约束_Java_Spring

Java org.springframework.dao.DataIntegrityViolationException:空约束

java spring

Java org.springframework.dao.DataIntegrityViolationException:空约束,java,spring,Java,Spring,我的模型包中有一个学生类，它的userid引用了user类中的userid @Entity @Table(name = "student") public class Student { @Id @Column(name = "Libraryid") private int libraryid; @Column(name = "Stdphone") private String phoneno; @Column(name = "stdmail") private String studentm

我的模型包中有一个学生类，它的userid引用了user类中的userid

@Entity
@Table(name = "student")
public class Student {

@Id
@Column(name = "Libraryid")
private int libraryid;
@Column(name = "Stdphone")
private String phoneno;
@Column(name = "stdmail")
private String studentmail;
@Column(name = "address")
private String address;
@Column(name = "academicsid")
private int academicid;
@Column(name = "user_userid", nullable = true)
private int userid;
@Column(name = "stdname")
private String studentname;

public String getStudentname() {
    return studentname;
}

public void setStudentname(String studentname) {
    this.studentname = studentname;
}

public int getLibraryid() {
    return libraryid;
}

public void setLibraryid(int libraryid) {
    this.libraryid = libraryid;
}

public String getPhoneno() {
    return phoneno;
}

public void setPhoneno(String phoneno) {
    this.phoneno = phoneno;
}

public String getStudentmail() {
    return studentmail;
}

public void setStudentmail(String studentmail) {
    this.studentmail = studentmail;
}

public String getAddress() {
    return address;
}

public void setAddress(String address) {
    this.address = address;
}

public int getAcademicid() {
    return academicid;
}

public void setAcademicid(int academicid) {
    this.academicid = academicid;
}

public int getUserid() {
    return userid;
}

public void setUserid(int userid) {
    this.userid = userid;
}

}

这是在数据库中添加学生的jsp文件，但我没有输入用户ID，因为我想在注册学生时输入

<body>
<form:form method="post"  modelAttribute="student"  action="admin">
    <table>

    <tr>
            <td><form:label path="libraryid">libraryid</form:label></td>
            <td><form:input path="libraryid" /></td>
        </tr>

        <tr>
            <td><form:label path="studentname">Name</form:label></td>
            <td><form:input path="studentname" /></td>
        </tr>
        <tr>
            <td><form:label path="phoneno">phoneno</form:label></td>
            <td><form:input path="phoneno" /></td>
        </tr>
        <tr>
            <td><form:label path="studentmail">studentmail</form:label></td>
            <td><form:input path="studentmail" /></td>
        </tr>
        <tr>
            <td><form:label path="academicid">academicid</form:label></td>
            <td><form:input path="academicid" /></td>
        </tr>

        <tr>
            <td><input type="submit" value="Save"></td>
        </tr>
    </table>


</form:form>

我有这个错误

  message Request processing failed; nested exception is org.springframework.dao.DataIntegrityViolationException: Cannot add or update a child row: a foreign key constraint fails (`sunwaylib`.`student`, CONSTRAINT `fk_student_user` FOREIGN KEY (`user_userid`) REFERENCES `user` (`Userid`) ON DELETE SET NULL ON UPDATE CASCADE); SQL [n/a]; constraint [null]; nested exception is org.hibernate.exception.ConstraintViolationException: Cannot add or update a child row: a foreign key constraint fails (`sunwaylib`.`student`, CONSTRAINT `fk_student_user` FOREIGN KEY (`user_userid`) REFERENCES `user` (`Userid`) ON DELETE SET NULL ON UPDATE CASCADE)

虽然我已经设置了数据库允许空值

但在学生表和用户表之间的数据库级别上有任何约束？是的，有学生表的userid引用了usertable中的userid主键。在学生表和用户表之间的数据库级别上有任何约束？是的，有学生表的userid引用了usertable中的userid主键引用usertable中的userid主键

  message Request processing failed; nested exception is org.springframework.dao.DataIntegrityViolationException: Cannot add or update a child row: a foreign key constraint fails (`sunwaylib`.`student`, CONSTRAINT `fk_student_user` FOREIGN KEY (`user_userid`) REFERENCES `user` (`Userid`) ON DELETE SET NULL ON UPDATE CASCADE); SQL [n/a]; constraint [null]; nested exception is org.hibernate.exception.ConstraintViolationException: Cannot add or update a child row: a foreign key constraint fails (`sunwaylib`.`student`, CONSTRAINT `fk_student_user` FOREIGN KEY (`user_userid`) REFERENCES `user` (`Userid`) ON DELETE SET NULL ON UPDATE CASCADE)