[英]Compare dates in T-SQL
我有一個數據類型為varchar
的列date
的表。 值為'2022-03-08 07:00',2022-03-08 07:30...
在我的存儲過程中,我有一個DATE
類型的參數,其值為'2022-3-8'
DECLARE @d DATE = '2022-3-8'
SELECT *, r.date AS date, @d AS d
FROM Readings AS r
WHERE CONVERT(VARCHAR, r.date, 23) = @d
我如何比較這兩者? 我收到此錯誤:
從字符串轉換日期和/或時間時轉換失敗。
我想刪除時間分量並比較'2022-03-08'
與'2022-3-8'
。 請注意月份和日期數字中的前導零。
TRY_CAST
或TRY_CONVERT
會將您的字符串轉換為日期,如果不可能則返回 null。
SELECT *, TRY_CAST(r.date AS DATE) as date, @d AS d
FROM Readings r
WHERE TRY_CAST(r.date AS DATE) = @d
例子:
DECLARE @d DATE = '2022-3-8';
WITH Readings AS
(
SELECT '2022-03-08 07:00' AS date
UNION ALL
SELECT '2022-03-08 07:30'
UNION ALL
SELECT '2022-03-06 17:30' --will be false
UNION ALL
SELECT '2022-02-31 07:30' --invalid string
)
SELECT r.date as OriginalString
, TRY_CAST(r.date AS DATE) as CastDate
, TRY_CONVERT(DATE,r.date,23) as ConvertDate
, @d AS d
, CASE WHEN TRY_CAST(r.date AS DATE) = @d THEN 1 ELSE 0 END AS Matched
FROM Readings r
使用right(replicate('0',2)+value,2)使您能夠將1 個一位數更改為兩位數( 1=>01 )。 使用PARSENAME進行拆分,使用concat進行連接字符串
DECLARE @d DATE = '2022-3-8'
SELECT Concat(( Parsename(Replace(@d, '-', '.'), 3) )/*year*/, '-', RIGHT(
Replicate('0', 2) + ( Parsename(Replace(@d, '-', '.'), 2) ), 2)
/*month*/,
'-', RIGHT(Replicate('0', 2) + ( Parsename(Replace(@d, '-', '.'),
1) ), 2
)/*day*/) as d
或在您的查詢中
DECLARE @d DATE = '2022-3-8'
SELECT *,
r.date
AS date,
,@d
FROM readings AS r
WHERE CONVERT(VARCHAR, r.date, 23) =
Concat(( Parsename(Replace(@d, '-', '.'), 3) )/*year*/, '-', RIGHT(
Replicate('0', 2) + ( Parsename(Replace(@d, '-', '.'), 2) ), 2)/*month*/,
'-',
RIGHT(Replicate('0', 2) + ( Parsename(Replace(@d, '-', '.'), 1) ), 2)
/*day*/)
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