如何識別T-SQL中的DATETIME NULL記錄？

Question

我正在開發下面的tsql查詢。我如何識別其中包含「1900％」的記錄？

SELECT DISTINCT TICKET, COMPLAINT_LEVEL, COMPLETION_DATE, DATE_FILTER, YEAR(DATE_FILTER) AS YEAR_FILTER, MONTH(DATE_FILTER) AS MONTH_FILTER, 
left(datename(month, DATE_FILTER), 3) + ' ''' + 
RIGHT(year(DATE_FILTER), 2) AS SHORT_DATE_FILTER, 
CASE WHEN DATE_FILTER < MONTH_END AND MONTH_END < CURRENT_DATE_END AND COMPLETION_DATE IS NULL THEN DATE_FILTER 
WHEN DATE_FILTER < MONTH_END AND MONTH_END < CURRENT_DATE_END AND 
COMPLETION_DATE IS NOT NULL AND ABS(DATEDIFF(DAY, COMPLETION_DATE, MONTH_END)) >= 1 AND DATE_FILTER < CURRENT_DATE_END THEN DATE_FILTER 
ELSE 0 END AS ROW_TYPE 
FROM #TEMP 
--WHERE row_type = 0 
--line above does not work 

這是我的輸出是什麼樣子

Answer 1

WHERE DATEPART(year, ROW_TYPE) = 1900 

http://msdn.microsoft.com/en-us/library/ms174420.aspx

Answer 2

似乎沒有日期時間具有空值。

雖然看起來只是檢查row_type。它不會工作，它是一個計算列。您需要將腳本更改爲此以檢查row_type，否則您需要與生成計算列的整個表達式進行比較。

SELECT * FROM (
SELECT DISTINCT TICKET, COMPLAINT_LEVEL, COMPLETION_DATE, DATE_FILTER, YEAR(DATE_FILTER) AS YEAR_FILTER, MONTH(DATE_FILTER) AS MONTH_FILTER, 
left(datename(month, DATE_FILTER), 3) + ' ''' + 
RIGHT(year(DATE_FILTER), 2) AS SHORT_DATE_FILTER, 
CASE WHEN DATE_FILTER < MONTH_END AND MONTH_END < CURRENT_DATE_END AND COMPLETION_DATE IS NULL THEN DATE_FILTER 
WHEN DATE_FILTER < MONTH_END AND MONTH_END < CURRENT_DATE_END AND 
COMPLETION_DATE IS NOT NULL AND ABS(DATEDIFF(DAY, COMPLETION_DATE, MONTH_END)) >= 1 AND DATE_FILTER < CURRENT_DATE_END THEN DATE_FILTER 
ELSE 0 END AS ROW_TYPE 
FROM #TEMP) a 
WHERE YEAR(ROW_TYPE) = 1900 

Answer 3

這會工作，以及：

WHERE ROW_TYPE = 0 

但是，正如@t-clausen.dk正確地指出的那樣，ROW_TYPE列不能同SELECT的WHERE子句中引用。通常你會添加一個外部的SELECT，所有內部SELECT的別名都可以訪問到。