java.sql.SQLException : Column 'max_grade' not Found where sql query do not contain 'max_grade' 异常

Question

我的问题是我试图从 3 个表连接中获取值。我的mysql查询如下。它工作正常，在 sql 控制台中没有任何错误。但是使用Java运行时报错:

StringBuilder queryString = new StringBuilder();
queryString.append("SELECT cs.id, MIN( s.grade_level_val ) as minGrade, MAX( s.grade_level_val ) as maxGrade FROM class_section cs ")
           .append("LEFT JOIN enrollment e ON e.class_section_id = cs.id ")
           .append("LEFT JOIN student s ON s.id = e.student_id ")
           .append("WHERE cs.id = :classSectionId");

TypedQuery<ClassSectionVO> query = (TypedQuery<ClassSectionVO>) entityManager.createNativeQuery(queryString.toString(), ClassSectionVO.class);
query.setParameter("classSectionId", classSectionId);

List<ClassSectionVO> result = query.getResultList();

这里是ClassSectionVO:

import java.io.Serializable;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;

@Entity
public class ClassSectionVO implements Serializable
{
    private static final long serialVersionUID = 1L;

    @Id
    @Column(name = "id")
    private Integer id;

    @Column(name = "minGrade")
    private Short minGrade;

    @Column(name = "maxGrade")
    private Short maxGrade;

    public Integer getId()
    {
        return id;
    }

    public void setId(Integer id)
    {
        this.id = id;
    }

    public Short getMinGrade()
    {
        return minGrade;
    }

    public void setMinGrade(Short minGrade)
    {
        this.minGrade = minGrade;
    }

    public Short getMaxGrade()
    {
        return maxGrade;
    }

    public void setMaxGrade(Short maxGrade)
    {
        this.maxGrade = maxGrade;
    }
}

查询中没有 max_grade 列，但它给了我错误:

java.sql.SQLException :column 'max_grade' not found.

Answer 1

如果您的 Configuration对象设置一个 ImprovedNamingStrategy , 然后 camelCase 名称被转换为 snake_case。

如果您不想要 snake_case，那么要么不设置命名策略，要么将其设置为 DefaultNamingStrategy .