Small question, how to get the number of days from a certain date in SQL?

苹果小刀

SELECT datediff (day, 'date to be compared', the field name to be compared by the database)
FROM table name
WHERE condition

菜鸟明星

Select
DATEDIFF (Day,
Convert (Datetime,
substring (
convert (varchar, getdate (), 112)
, 1,4)
+ substring (
Cast (Birthday As Varchar)
, 5, len (Birthday)
), 112),
getdate ()
)

psycholmu

SELECT DATEDIFF ([day], CONVERT (datetime, SUBSTRING (CONVERT (varchar, GETDATE (),
      112), 1, 4) + SUBSTRING (CONVERT (varchar, BirthDate, 112), 5, LEN (BirthDate)), 112),
      GETDATE ()) AS Expr1
FROM Employees

shygza

Hey, LZ should strengthen exercise, analyze more, and learn to make inferences.

Birthday is your DateTime field, my example just dealt with the case of strings, you can put two
'20000101' string
Replace with
convert (varchar, Birthday, 112)

Convert the date to a string with convert and then process

psycholmu

I did n’t look at the specific calculations. I do n’t know if the logic is correct or not. I just converted the datetime type and asked lz to compare it myself.

流星飞舞

Thank you for your advice, andshygzaagain