现在获取月份和年份，然后计算 SQL/Classic ASP 中超过 12 个月的行数

Question

I know this one is pretty easy but I've always had a nightmare when it comes to comparing dates in SQL please can someone help me out with this, thanks.

I need to get the month and year of now then compare it to a date stored in a DB.

Time Format in the DB:

2015-08-17 11:10:14.000

I need to compare the month and year with now and if its > 12 months old I will increment a count. I just need the number of rows where this argument is true.

Answer 1

I assume you have a datetime field.

You can use the DATEDIFF function, which takes the kind of "crossed boundaries", the start date and the end date.
Your boundary is the month because you are only interested in year and month, not days, so you can use the month macro.
Your start time is the value stored in the table's row.
Your end time is now. You can get system time selecting SYSDATETIME function.

So, assuming your table is called mtable and the datetime object is stored in its date field, you simply have to query:

SELECT COUNT(*) FROM mtable where DATEDIFF(month, mtable.date, (SELECT SYSDATETIME())) > 12