谁能帮我把sql中的字符串表示形式的值转换成int吗。例如，我在sql表中有'five'varchar文件，我需要使用sql查询将其转换为5。至少可以只用sql来实现。
是否有可能在criteriaapi中实现它。
主要目标是将所有字符串字段转换为数字表示，并找到每个productid的平均值。
实体：

@Entity
@Table(name = "product_review")
public class ProductReview {

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "prod_rev_seq")
    private Long id;

    @ManyToOne(optional = false)
    @JoinColumn(name = "prod_id")
    private Product product;

    @Enumerated(EnumType.STRING)
    private Rating rating;
}

@Entity
@Table(name = "product")
public class Product {

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "prod_seq")
    @Column(name = "prod_id")
    private Long id;

    @OneToMany(mappedBy = "product", fetch = FetchType.LAZY,
    private Set<ProductReview> productReviews = new HashSet<>();

}

public enum Rating implements JsonDeserializableEnum {

ONE(BigDecimal.ONE, "Horrible", BigDecimal.ZERO, BigDecimal.valueOf(1.5)),
ONE_AND_HALF(BigDecimal.valueOf(1.5), "Poor", BigDecimal.valueOf(1.5), BigDecimal.valueOf(2)),
TWO(BigDecimal.valueOf(2), "Poor", BigDecimal.valueOf(2), BigDecimal.valueOf(2.5)),
TWO_AND_HALF(BigDecimal.valueOf(2.5), "Below average", BigDecimal.valueOf(2.5), BigDecimal.valueOf(3)),
THREE(BigDecimal.valueOf(3), "Average", BigDecimal.valueOf(3), BigDecimal.valueOf(3.5)),
THREE_AND_HALF(BigDecimal.valueOf(3.5), "Average", BigDecimal.valueOf(3.5), BigDecimal.valueOf(4)),
FOUR(BigDecimal.valueOf(4), "Good", BigDecimal.valueOf(4), BigDecimal.valueOf(4.5)),
FOUR_AND_HALF(BigDecimal.valueOf(4.5), "Very good", BigDecimal.valueOf(4.5), BigDecimal.valueOf(5)),
FIVE(BigDecimal.valueOf(5), "Excellent", BigDecimal.valueOf(5), BigDecimal.valueOf(5.5));

}

“五”-5
“三”-3
等
提前谢谢！