Checking if the “system” falls between two dates in SQL

问题

The Scenarion is DEMO001 system is booked from 10-Aug to 11-Aug by some user.

START_DATE     END DATE    SYSTEM
2016-08-10     2016-08-11  DEMO001
2016-09-05     2016-09-08  DEMO001
2016-08-08     2016-08-11  DEMO013
2016-08-16     2016-08-18  DEMO017

If Other user tries to book this system between these days . We have to check and pass 0 or 1.

I will get an input parameter

1) start_date as 2016-08-08 and 2016-08-15.
2) 2016-09-06 and 2016-09-07
3) 2016-08-08 and 2016-08-09

I have to write a PLSQL/SQL code to pass 0 because DEMO001 is falling between these start data and end date of the input else pass 1.

Kindly help.

回答1:

Oracle Setup:

CREATE TABLE table_name ( START_DATE, END_DATE, SYSTEM ) AS
SELECT DATE '2016-08-10', DATE '2016-08-11', 'DEMO001' FROM DUAL UNION ALL
SELECT DATE '2016-09-05', DATE '2016-09-08', 'DEMO001' FROM DUAL UNION ALL
SELECT DATE '2016-08-08', DATE '2016-08-11', 'DEMO013' FROM DUAL UNION ALL
SELECT DATE '2016-08-16', DATE '2016-08-18', 'DEMO017' FROM DUAL;

Query:

With the bind variables :start_date and :end_date as the inputs:

SELECT system,
       MIN(
         CASE
         WHEN :end_date < start_date OR :start_date > end_date
         THEN 1
         ELSE 0
         END
       ) AS can_book
FROM   table_name
GROUP BY system;

Output:

For the inputs :start_date = DATE '2016-08-08' and :end_date = DATE '2016-08-15':

SYSTEM    CAN_BOOK
------- ----------
DEMO001          0 
DEMO013          0 
DEMO017          1

For the inputs :start_date = DATE '2016-09-06' and :end_date = DATE '2016-09-07':

SYSTEM    CAN_BOOK
------- ----------
DEMO001          0 
DEMO013          1 
DEMO017          1

For the inputs :start_date = DATE '2016-08-08' and :end_date = DATE '2016-08-09':

SYSTEM    CAN_BOOK
------- ----------
DEMO001          1 
DEMO013          0 
DEMO017          1

回答2:

Based on your requirements, you want to disallow a booking if either the start or end date falls in between a given record. You can just use a CASE expression for this. I have hardcoded 2016-08-08 and 2016-08-15 as the start and end dates which you are using.

SELECT SYSTEM,
    CASE WHEN (DATE '2016-09-06' < START_DATE AND DATE '2016-09-07' < START_DATE) OR
              (DATE '2016-09-06' > END_DATE AND DATE '2016-09-07' > END_DATE)
         THEN 1
         ELSE 0
    END AS allowBooking
FROM yourTable

Here is a link to a SQL Fiddle showing the query in action for the input range of 2016-08-08 to 2016-08-09. It clearly shows that all bookings are possible except for DEMO013. I used MySQL but the logic should not change in going from MySQL to Oracle or vice-versa.

SQLFiddle

来源：https://stackoverflow.com/questions/37670170/checking-if-the-system-falls-between-two-dates-in-sql

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