如何将 MSSQL CTE 查询转换为 MySQL 5.7？

Question

我有一个 SQL 个查询

with temp as 
(
select min(ms_date) as start, max(ms_date) as [end], count(sessionid) 'visitor_count',category,convert(varchar, ms_date , 106) 'ms_date'        
from temp_tbltrack  where category =@id         
group by category,convert(varchar, ms_date , 106)
)
select category,ms_date,CASE WHEN datediff(ss,temp.start,temp.[end]) <>0 THEN datediff(ss,temp.start,temp.[end]) ELSE 45 END 'Timespan',visitor_count from temp
order by convert(datetime,ms_date)

我转换成Mysql

select temp from 
(
select min(ms_date) as start, max(ms_date) as `end`, count(sessionid) 'visitor_count',category,date_format (ms_date , 106) 'ms_date'        
from temp_tbltrack  where category =p_id         
group by category,date_format (ms_date , 106)
)
select category,ms_date,CASE WHEN timestampdiff(ss,temp.start,temp.[end]) <>0 THEN timestampdiff(ss,temp.start,temp.[end]) ELSE 45 END 'Timespan',visitor_count from temp
order by convert(ms_date, datetime);

我如何在 Mysql 5.7 版本

中转换 CTE

Answer 1

您可以使用子查询，因为您不能在 mysql 版本上使用 cte。

select t1.category
    , t1.ms_date
    , case when datediff(ss, temp.start, temp.[end]) <> 0 
        then datediff(ss,temp.start,temp.[end]) else 45 end 'Timespan' 
    , t1.visitor_count
from 
    (select min(ms_date) as start, max(ms_date) as [end], count(sessionid) 'visitor_count', category, cast(ms_date as date) 'ms_date'        
    from temp_tbltrack  where category =@id         
    group by category, cast(ms_date as date)) t1
order by cast(t1.ms_date as datetime)

Answer 2

我认为不需要子查询：

select category,
       format(ms_date, '%d %b %Y') as ms_date,
       (case when max(ms_date) = min(ms_date)
             then 45
             else timestampdiff(second, min(ms_date), max(ms_date))
        end) as timestamp
       count(sessionid) as `visitor_count`,
from temp_tbltrack 
where category = @id         
group by category, format(ms_date, '%d %b %Y')
order by min(ms_date);

如何将 MSSQL CTE 查询转换为 MySQL 5.7？

How to transform a MSSQL CTE query to MySQL 5.7?

mysql

sql

sql-server

common-table-expression

mysql-5.7