允许基于预订-SQL更新的方案

Question

方案是DEMO001系统由用户在8月10日至11月8日预订.

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

假设我得到一个输入参数

1) start date as 2016-08-08  and end date as 2016-08-11 I can allow 
2) start date as 2016-08-11  and end date as 2016-09-08 I cannot allow
3) start date as 2016-08-10   and end date as 2016-08-15 I can allow
3) start date as 2016-08-10   and end date as 2016-09-06 I cannot allow

如果用户试图通过延长或推迟开始或结束日期来更新任何此系统,如果在这些天之间没有其他人预订,我将不得不说0或1.

这是此方案的扩展

检查"系统"是否落在SQL中的两个日期之间

我尝试修改它给出的建议,但无法正确使用它.请建议.

Answer 1

如果我正确理解您的问题，您正在寻找一种通用的解决方案来区分资源的时间段是否在时间上重叠。

假设前四个示例行是名为 BOOKING 的表中的列，并且您想要测试首次预订的新日期，则可以使用如下查询来执行此操作：

CREATE TABLE booking( system_name  VARCHAR2( 10 )
                    , start_date   DATE
                    , end_date     DATE
                     );

INSERT INTO booking( system_name, start_date, end_date )
         VALUES ( 'DEMO001'
                , TO_DATE( '2016-09-05', 'YYYY-MM-DD' )
                , TO_DATE( '2016-09-08', 'YYYY-MM-DD' )
                 );
-- You only need this record, as you need to filter on the system name anyway
COMMIT;

SELECT CASE COUNT( 1 ) WHEN 0 THEN 'I can allow' ELSE 'I cannot allow' END
           AS outcome
  FROM DUAL
 WHERE EXISTS
           (SELECT 1
              FROM booking old
             WHERE old.system_name = 'DEMO001'
               AND old.end_date > TO_DATE( '2016-08-08', 'YYYY-MM-DD' )
               AND old.start_date < TO_DATE( '2016-08-08', 'YYYY-MM-DD' ));

SELECT CASE COUNT( 1 ) WHEN 0 THEN 'I can allow' ELSE 'I cannot allow' END
           AS outcome
  FROM DUAL
 WHERE EXISTS
           (SELECT 1
              FROM booking old
             WHERE old.system_name = 'DEMO001'
               AND old.end_date > TO_DATE( '2016-08-11', 'YYYY-MM-DD' )
               AND old.start_date < TO_DATE( '2016-09-08', 'YYYY-MM-DD' ));

SELECT CASE COUNT( 1 ) WHEN 0 THEN 'I can allow' ELSE 'I cannot allow' END
           AS outcome
  FROM DUAL
 WHERE EXISTS
           (SELECT 1
              FROM booking old
             WHERE old.system_name = 'DEMO001'
               AND old.end_date > TO_DATE( '2016-08-10', 'YYYY-MM-DD' )
               AND old.start_date < TO_DATE( '2016-08-15', 'YYYY-MM-DD' ));

SELECT CASE COUNT( 1 ) WHEN 0 THEN 'I can allow' ELSE 'I cannot allow' END
           AS outcome
  FROM DUAL
 WHERE EXISTS
           (SELECT 1
              FROM booking old
             WHERE old.system_name = 'DEMO001'
               AND old.end_date > TO_DATE( '2016-08-10', 'YYYY-MM-DD' )
               AND old.start_date < TO_DATE( '2016-09-06', 'YYYY-MM-DD' ));

当然，CASE 语句只是为了使测试结果直观清晰。如果您想要 0 和 1 得到相反的结果，只需将其设置为“NOT EXIST”即可