mysql实现游标分页的方法详解

SELECT * FROM loc_common_info 
WHERE id NOT IN (1,2,3)  -- 假设用户去过场地1,2,3
AND status = 'ACTIVE'
ORDER BY popularity_score DESC, id DESC
LIMIT 3;  -- 假设每页3条

SELECT * FROM loc_common_info 
WHERE id NOT IN (1,2,3) 
AND status = 'ACTIVE'
-- 关键条件：找到排在"最后一条记录"之后的所有记录
AND (popularity_score < #{lastScore} 
     OR (popularity_score = #{lastScore} AND id < #{lastId}))
ORDER BY popularity_score DESC, id DESC
LIMIT 3;

AND (
    popularity_score < 90 
    OR 
    (popularity_score = 90 AND id < 5)
)

// 第一页请求
PageRequest request1 = new PageRequest(0, 3, null); // 没有游标
PageResult result1 = service.getRecommendations(request1);

// 返回结果包含下一页游标
String nextCursor = result1.getNextCursor(); // 编码为: "90_5"

// 第二页请求
PageRequest request2 = new PageRequest(0, 3, "90_5"); // 使用游标
PageResult result2 = service.getRecommendations(request2);

-- 第一页
SELECT ... LIMIT 0, 3;  -- 返回记录1,2,3

-- 第二页  
SELECT ... LIMIT 3, 3;  -- 返回记录4,5,6

-- 第一页：返回id=10,8,5，记住lastScore=90, lastId=5
-- 第二页：查询score<90 OR (score=90 AND id<5)的记录

@Data
public class RecommendationCursor {
    private String type;        // "new", "rotate", "retain"
    private Double lastScore;   // 上一页最后一条的popularity_score
    private Long lastId;        // 上一页最后一条的ID
    private Integer page;       // 当前页码
    private String randomSeed;  // 随机种子
    
    public static RecommendationCursor parseCursor(String cursorStr, String type) {
        if (cursorStr == null) {
            return new RecommendationCursor(type, null, null, 0, generateRandomSeed());
        }
        // 解析游标逻辑...
    }
    
    public String toCursorString() {
        // 生成游标字符串逻辑...
    }
}