考虑一个日间实地<代码>Fld1。
我如何利用QQQ的问询,检查这一数值在3个月前是否老?
从你的其他问题来看,它像服务器。
所提供的2个服务器的答案不是SARGable (link);不能使用索引。
WHERE datecolumn < DATEADD(month, -3, GETDATE())
Construct a date 3 months ago and test against it; this will be able to use indexes. This statement holds true for any DBMS.
If you are after full calendar months, e.g.
。
WHERE datecolumn <= DATEADD(month, datediff(month, 0, getdate()) -2, 0)
<>SQL服务器:
select * from table where DATEDIFF(m, dateColumn, GETDATE()) < 3
MySQL
SELECT * FROM table WHERE Fld1 <= DATE_SUB(CURDATE(), INTERVAL 3 MONTH)
这将选择3个月以上的要素。 如果在3个月前需要新内容,仅改动<代码><=至>=。
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