在指定日期范围内从数据库中选择数据

Question

I have a database with employee information and a program, which is supposed to retrieve data from this database.

The database structure seems like this:

ID | Date        | signedIn | SignedOut
1    01-10-2012    08:00:00   16:00:00
1    14-10-2012    08:00:00   16:00:00
1    13-09-2012    08:00:00   16:00:00

When I then try to retrieve data between 01-10-2012 and 15-10-2012 I want go get only the first two rows. So I get a total amount of hours worked to 16.

But right now I get the total amount to 24, because it also retrieves the last one, even though it is from last month

sql sentence:

SELECT Info.UserID, Info.SurName, Info.FirstName, timetabel.Date, 
FROM Info
INNER JOIN timestabel
ON Info.UserID = Bruger_tidstabel.UserID
WHERE Info.UserID = '1'
AND timetabel.Date >= '01-10-2012'
AND timetabel.Date <= '14-10-2012'"

the sentence works, so it can retrieve data from database.

Is there any way to tell the database, I am working with dates, so it will only retrieve data between two surden dates??

Answer 1

Try the BETWEEN Statement, like:

"... WHERE Info.UserID = '1' AND (timetabel.Date BETWEEN '01-10-2012' AND '14-10-2012')"

Check with or without the () .. Also check if the date pattern is correct, depends on your database.

Answer 2

You can use the BETWEEN operator, it is used in a WHERE clause to select a range of data between two values.

SELECT column_name(s)
 FROM table_name
 WHERE column_name
 BETWEEN value1 AND value2

It is good idea your table field Date to be in date or time stamp format. Also, the year goes on front of the date format, like this:

SELECT Info.UserID, Info.SurName, Info.FirstName, timetabel.Date, FROM Info INNER JOIN timestabel ON Info.UserID = Bruger_tidstabel.UserID WHERE Info.UserID = '1' AND timetabel.Date BETWEEN '2012-10-01' AND '2012-10-14'

Answer 3

You always need to be careful when representing dates as strings since as Christian says, they are not always treated as expected. Ensure you use datetime types or use one of the date functions (DATEADD, DATEDIFF, etc) so that you are comparing dates with dates! Unfortunately the SQL will often run without error but what it has intepreted from your SQL is not always as expected!

Answer 4

While not answering your question directly (other answered already), I would like to warn you from a common pitfall when working with date ranges.

timetabel.Date <= '14-10-2012'

What happens if the date/time stored in timetabel.Date is 14-10-2012 08:30 ? This date will be excluded. Personally I prefer to use this safer test

timetabel.Date < '15-10-2012'

this is equivalent to the above one (except for the time part of cause). So instead of comparing

table.column <= date

I compare

table.column < (date + one day)