Spring Boot:使用JPA希望从表中获取唯一值
我有一张桌子
CatID |分类名称| scatID | subCategoryName 2个用户1 x 2用户2年 2用户3 z 2用户4 a 2位用户5 b
CatID | CategoryName | scatID | subCategoryName 2 User 1 x 2 User 2 y 2 User 3 z 2 User 4 a 2 User 5 b
我能够使用SpringBoot获取JSON formate中的所有值.
I am able to get all the value in JSON formate using SpringBoot.
我的要求: 我想获得唯一的CategoryName属性,但在当前情况下,我将使所有用户获得5次访问.
My Requirement : I want to get the unique CategoryName attribute but in current scenario I am getting all User coming 5 times.
我正在寻找解决方案.请任何人都可以帮助克服使用Spring Boot JPA的实现.
I am looking for solution. Please any one can help to get over using Spring Boot JPA implementation.
您可以在存储库界面中使用Query
批注.
例如,下面的代码段返回所有不同的categoryName
.
You can use the Query
annotation in your repository interface.
For example, below snippet code return all distinct categoryName
.
声明一个简单的bean类:
Declare a simple bean class:
package com.example.test;
public class CategoryNameClass {
private String CategoryName;
public CategoryNameClass(String CategoryName) {
this.CategoryName = CategoryName;
}
public String getCategoryName() {
return CategoryName;
}
public void setCategoryName(String categoryName) {
CategoryName = categoryName;
}
}
然后使用以下查询:
public interface ARepo extends JpaRepository<A, String> {
@Query("SELECT DISTINCT new com.example.test.CategoryNameClass(a.categoryName) FROM A a ")
List<CategoryNameClass> findAllCategoryName();
}