Update one table based on condition from another table using date ranges

Question

Hello!
I have two tables:
DateRange (consists of ranges of dates):
StartDate            FinishDate
        Condition
2014-01-02
      2014-01-03           true
2014-01-03     
 2014-01-13          
false
2014-01-13      
2014-01-14           true
Calendar (consists of three-year dates):
CalendarDate    IsParental
2014-01-01
2014-01-02
2014-01-03
2014-01-04
2014-01-05
2014-01-06
2014-01-07
2014-01-08
2014-01-09
2014-01-10
I want to update table Calendar by setting  IsParental=1
  for those dates that are contained in table DateRange between
StartDate and FinishDate AND Condition  IS TRUE.
The query without loop should look similar to this but it works wrong:
UPDATE
Calendar
SET IsParental = 1
 WHERE
CalendarDate   BETWEEN
(SELECT
StartDate 
FROM  DateRange
WHERE Calendar.  CalendarDate   = DateRange. StartDate
           AND   
(SELECT StartDate 
FROM  DateRange
WHERE Calendar.  CalendarDate   = DateRange. FinishDate
AND Condition
 IS TRUE
Is it possible to do without loop? Thank you for help!
Anastasia

Answer 1

Hi
Please post DDL+DML next time :-)
-- This is the DDL! create the database structure
create table DateRange(
StartDate DATE,
FinishDate DATE,
Condition BIT
GO
create table Calendar(
CalendarDate DATE,
IsParental BIT
GO
-- This is the DML (insert some sample data)
insert DateRange
values
('2014-01-02', '2014-01-03', 1),
('2014-01-03', '2014-01-13', 0),
('2014-01-13', '2014-01-14', 1)
GO
insert Calendar(CalendarDate)
values
('2014-01-01'),
('2014-01-02'),
('2014-01-03'),
('2014-01-04'),
('2014-01-05'),
('2014-01-06'),
('2014-01-07'),
('2014-01-08'),
('2014-01-09'),
('2014-01-10')
select * from DateRange
select * from Calendar
GO
-- This is the solution
select CalendarDate
from Calendar C
where EXISTS (
select C.CalendarDate
FROM DateRange D
where C.CalendarDate between D.StartDate and D.FinishDate and D.Condition = 1
UPDATE Calendar
SET IsParental = 1
from Calendar C
where EXISTS (
select C.CalendarDate
FROM DateRange D
where C.CalendarDate between D.StartDate and D.FinishDate and D.Condition = 1
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