MySQL的轉換爲datetime語法錯誤：意外IDENT_QUOTED

Question

我們已經運行完全在MSSQL，但未能在MySQL運行下面的查詢：

select CONVERT(datetime, dateVal) as DateOccurred, itemID, COUNT(*) as Hits from (
select itemID, CONVERT(datetime, DateClickUTC) as dateVal 
from tb_items 
where DateClickUTC >= '2008-06-03 22:00:28.893' and DateClickUTC <= '2013-06-03 22:00:28.893' 
group by CONVERT(datetime, DateClickUTC), UserID, itemID) as a 
group by a.dateVal, itemID 

我們從MySQL得到的錯誤說：

syntax error, unexpected IDENT_QUOTED

第一行上的dateVal變量發生此錯誤：「選擇CONVERT（日期時間，dateVal）」。

如果我們刪除第一個CONVERT，那麼錯誤將轉到下一行的下一個CONVERT。所以，顯然，我們的日期時間轉換似乎存在錯誤。不知道我們做錯了什麼，有什麼想法嗎？謝謝大家。

Answer 1

我更喜歡使用CAST，但是正如其他人所說，你需要這樣的後場指定類型：

convert(DateClickUTC,datetime) 

下面是使用CAST工作示例：

select a.dateVal as DateOccurred, itemID, COUNT(*) as Hits 
from (
    select itemID, cast(DateClickUTC as datetime) as dateVal 
    from tb_items 
    where DateClickUTC >= '2008-06-03 22:00:28.893' and DateClickUTC <= '2013-06-03 22:00:28.893' 
    group by cast(DateClickUTC as datetime), UserID, itemID 
) as a 
group by a.dateVal, itemID 

• SQL Fiddle Demo

順便說一句 - 你其實並不需要在這種情況下，子查詢 - 這應該工作以及：

select cast(DateClickUTC as datetime) as DateOccurred, 
    itemID, 
    COUNT(*) as Hits 
from tb_items 
where DateClickUTC >= '2008-06-03 22:00:28.893' and DateClickUTC <= '2013-06-03 22:00:28.893' 
group by cast(DateClickUTC as datetime), itemID