SQL question, query, procedure or function
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P粉253518620 2024-04-03 10:14:31
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This is the description.

There is a table that lists the time intervals required to perform a specific task:

id start Finish
1 07:00:00 11:00:00
2 12:30:00 17:00:00
3 11:30:00 14:00:00
4 09:30:00 11:30:00
5 10:00:00 15:00:00
6 09:00:00 13:30:00
7 07:00:00 11:30:00

These tasks cannot be completed at the same time. I need to find out the minimum number of days required to complete all tasks.

In this table, I can spend at least 5 days to complete the task.

day 1 => task 1 and task 2
day 2 => task 4 and task 3
day 3 => task 5
day 4 => task 6
day 5 => task 7

So the result should be 5. I hope it's clear, thank you in advance!

P粉253518620
P粉253518620

reply all(1)
P粉195200437
SELECT COUNT(*)
FROM test t1
JOIN test t2 ON 
-- these 2 conditions checks for overlapping
                t1.start 

You must simply calculate the maximum number of simultaneous tasks. It is enough to check the start time of each task.

https://dbfiddle.uk/?rdbms=mysql_8.0&fiddle=ee3034a307c32212db365ba06f654f9f 一个>

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