select date_pre, count(CASE WHEN DATEDIFF(date_pre, date_rete) = 1 THEN '是' else null END) / COUNT(DISTINCT role_id) AS retention_rate FROM ( SELECT role_id,dt as date_pre,lead(dt,1)over (partition by role_id) as date_rete FROM (select distinct role_id,dt from src_house_day order by role_id,dt) WHERE dt between 20230427 and 20230503 ) GROUP BY date_pre;有什么问题

这个 SQL 查询语句中，使用了 CASE WHEN 语句来判断两个日期之间相差一天的记录，然后统计了符合条件的记录数，并且除以了不同角色数量，计算出了留存率。但是，这个查询语句中没有指定表名，也没有给出 src_house_day 表的字段名和表结构，所以无法确定这个查询语句是否正确，可能存在语法错误或逻辑错误。

相关问题

请给我解释下面的sql语句含义：CASE WHEN first_consume IS NULL OR first_consume = '' THEN 1 WHEN form_priority in ('p0', 'P0') THEN ( CASE WHEN dateDiff(toMonday(toDate(created_time)), toDate(created_time)) < 5 AND toFloat32OrZero(first_consume)/60 <= 5 THEN 1 WHEN dateDiff(toMonday(toDate(created_time)), toDate(created_time)) >= 5 AND toFloat32OrZero(first_consume)/60 <= 5 THEN 1 ELSE 0 END ) WHEN form_priority in ('p1','P1') THEN ( CASE WHEN dateDiff(toMonday(toDate(created_time)), toDate(created_time)) < 15 AND toFloat32OrZero(first_consume)/60 <= 15 THEN 1 WHEN dateDiff(toMonday(toDate(created_time)), toDate(created_time)) >= 5 AND toFloat32OrZero(first_consume)/60 <= 30 THEN 1 ELSE 0 END ) WHEN form_priority in('p2', 'P2') THEN ( CASE WHEN toFloat32OrZero(first_consume)/60 <= 30 THEN 1 ELSE 0 END ) ELSE 0 END

这是一条 SQL 语句，主要是用于对数据表中的数据进行判断和计算，返回一个值。具体如下：

当 "first_consume" 字段为 NULL 或空字符串时，返回 1；

当 "form_priority" 字段等于 'p0' 或 'P0' 时，再根据 "created_time" 和 "first_consume" 字段的值，进行一系列判断，如果符合条件就返回 1，否则返回 0；

当 "form_priority" 字段等于 'p1' 或 'P1' 时，同上进行判断；

当 "form_priority" 字段等于 'p2' 或 'P2' 时，只需要判断 "first_consume" 字段的值是否小于等于 30，是则返回 1，否则返回 0；

当 "form_priority" 字段不属于上述三种情况时，返回 0。

with t as( select t1.video_id,COUNT(case when DATEDIFF(SECOND,t1.start_time,t1.end_time)>=t2.duration then 1 end) complete_qty, count(1) total_qty,COUNT(IIF(if_like=1,1,null)) like_qty,COUNT(IIF(if_retweet=1,1,null)) zf_qty, COUNT(comment_id) pl_qty,max(CAST(end_time as date)) v_last_playdate from tb_user_video_log t1 join tb_video_info t2 on t1.video_id=t2.video_id where DATEDIFF(DAY,release_time,(select max(end_time) from tb_user_video_log))<=29 group by t1.video_id ) select t.video_id,CAST((100*complete_qty*1.0/total_qty+5*like_qty+3*pl_qty+2*zf_qty)*1.0 /((DATEDIFF(DAY,v_last_playdate,(select max(end_time) from tb_user_video_log)))+1) as int) from t 优化以上sql

以下是对以上 SQL 进行优化的改进：

WITH t AS (
    SELECT t1.video_id,
        COUNT(CASE WHEN DATEDIFF(SECOND, t1.start_time, t1.end_time) >= t2.duration THEN 1 END) complete_qty,
        COUNT(*) total_qty,
        COUNT(CASE WHEN if_like = 1 THEN 1 END) like_qty,
        COUNT(CASE WHEN if_retweet = 1 THEN 1 END) zf_qty,
        COUNT(comment_id) pl_qty,
        MAX(CAST(end_time AS DATE)) v_last_playdate
    FROM tb_user_video_log t1
    JOIN tb_video_info t2 ON t1.video_id = t2.video_id
    WHERE DATEDIFF(DAY, release_time, (SELECT MAX(end_time) FROM tb_user_video_log)) <= 29
    GROUP BY t1.video_id
)

SELECT t.video_id, 
    CAST((100 * complete_qty * 1.0 / total_qty + 5 * like_qty + 3 * pl_qty + 2 * zf_qty) * 1.0 
        / (DATEDIFF(DAY, v_last_playdate, max_end_time) + 1) AS INT)
FROM t, (SELECT MAX(end_time) as max_end_time FROM tb_user_video_log) AS max_end

此优化后的 SQL 语句主要做了以下改进：
1. 使用 WITH 子句创建了一个临时视图，避免了嵌套子查询。
2. 将子查询 (SELECT MAX(end_time) FROM tb_user_video_log) 移至外部，并使用别名 max_end。
3. 在主查询中使用了 max_end.max_end_time，避免了重复计算。
4. 将 FROM t, (SELECT MAX(end_time) as max_end_time FROM tb_user_video_log) AS max_end 用于将两个查询结果合并。

这些优化措施可以提高查询的性能和可读性。请注意，具体的优化效果还需要考虑数据库的索引和数据量等因素。