Question

Below is the given table data:

CREATE TABLE #tbl_period (
    period_no INT,
    period_from SMALLDATETIME,
    period_to SMALLDATETIME
)

INSERT INTO #tbl_period (period_no, period_from, period_to)
VALUES (1, '2004-11-01 00:00:00', '2005-10-31 00:00:00')

INSERT INTO #tbl_period (period_no, period_from, period_to)
VALUES (2, '2005-11-01 00:00:00', '2006-10-31 00:00:00')

INSERT INTO #tbl_period (period_no, period_from, period_to)
VALUES (3, '2006-11-01 00:00:00', '2007-10-31 00:00:00')

INSERT INTO #tbl_period (period_no, period_from, period_to)
VALUES (4, '2007-11-01 00:00:00', '2008-10-31 00:00:00')

INSERT INTO #tbl_period (period_no, period_from, period_to)
VALUES (5, '2008-11-01 00:00:00', '2009-10-31 00:00:00')

INSERT INTO #tbl_period (period_no, period_from, period_to)
VALUES (6, '2009-11-01 00:00:00', '2010-10-31 00:00:00')

INSERT INTO #tbl_period (period_no, period_from, period_to)
VALUES (7, '2010-11-01 00:00:00', '2011-10-31 00:00:00')

SELECT * FROM #tbl_period

DROP TABLE #tbl_period

Now, The goal is to retrieve the period_no which having 2 given dates who will be compared to period_from and period_to columns.

Example1:
date1 = '2010-11-01 00:00:00'
date2 = '2011-10-31 00:00:00'

This will return 7 as the period_no

Example2: 
date1 = '2005-11-01 00:00:00'
date2 = '2007-10-31 00:00:00'

It should not return a period_no because the date range given does not in the range of period_from and period_to column in a row. Overlap dates is not allowed.

The rule is to retrieve a period_no if the 2 given date will have a match or be in a range of period_from and period_to column in a row.

How to do this query in T-SQL?

Thanks in advance!

Answer 1

I reckon this is what you’re after:

SELECT 
    *
FROM 
    #tbl_period 
WHERE 
    @date1 >= period_from 
    and
    @date2 <= period_to

Tests:

declare @date1 datetime = '2010-11-01 00:00:00' 
declare @date2 datetime = '2011-10-31 00:00:00' 

SELECT * FROM #tbl_period WHERE @date1 >= period_from and @date2 <= period_to

returns

period_no    period_from          period_to
7            2010-11-01 00:00:00  2011-10-31 00:00:00

and

set @date1 = '2005-11-01 00:00:00' 
set @date2 = '2007-10-31 00:00:00' 

SELECT * FROM #tbl_period WHERE @date1 >= period_from and @date2 <= period_to

returns

period_no   period_from period_to