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POComplex SQL statement feasibility
 

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  1. POComplex SQL statement feasibility
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    <p>I am currently developing a database system for a school that will work with our booking system so students can book their courses and we can better track their activity. Right now I am faced with a complex issue, what I want to do is check which student contracts are valid, I can do so by using the following function, but I want to see if there is an easier way to properly do it (besides storing data I can compute in the system.) </p> <p>If a contract is valid then the student has not used up all the hours they have purchased, hours purchased is the sum of the length of teach class they have attended added to the sum of the lengths of each class they missed but booked (after a certain number, such as 3 or 5). I can do it with the following query but I feel like there must be a simpler way:</p> <pre><code>SELECT level.name FROM ( SELECT contract.level_package_id, contract_class_hours.hours_purchased, ( SELECT isnull(sum(DATEPART(hh, class.end_date - class.start_date)), 0) FROM booking JOIN class ON class.id = booking.class_id WHERE booking.booking_state_id = 3 AND booking.contract_id = contract.id ) AS time_attended, ( SELECT isnull(sum(absent_class_lengths.length), 0) FROM ( SELECT DATEPART(hh, class.end_date - class.start_date) AS length, row_number() OVER (ORDER BY class.start_date) AS rn FROM booking JOIN class ON class.id = booking.class_id WHERE student_id = 5 AND booking_state_id = 4 AND booking.contract_id = contract.id ) absent_class_lengths WHERE rn &gt; contract_class_hours.absences_allowed ) as time_absent FROM contract JOIN contract_class_hours ON contract_class_hours.contract_id = contract.id ) test JOIN level_package_level ON level_package_level.level_package_id = test.level_package_id JOIN level ON level.id = level_package_level.level_id WHERE test.time_absent + test.time_attended &lt; test.hours_purchased AND level.study_type_id = 2 </code></pre> <ul> <li>booking.state_id = 3 means the student attended class </li> <li>booking.state_id = 4 means the student was absent </li> <li>level.study_type_id = 2 is just a course subject</li> </ul> <p>The tables contain data columns like these (ignore level_id, it is just a value I need to return):</p> <pre><code>CLASS id - int end_date - datetime start_date - datetime BOOKING id - int class_id - int student_id - int booking_state_id - smallint BOOKING_STATE id - int state - varchar(20) [absent, attended] CONTRACT id - int student_id - int level_id - int hours_purchased - smallint absenses_allowed - smallint STUDENT id - int </code></pre> <p>I realize this may be to complicated a question to ask, but I am just wondering if this really is the proper way to do things, or if I should just save some sort of field in the contract table that has a number of hours attended and assume it is always accurate.</p>
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    1. PO
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    1. PTQuestion
    1. USBenjamin Danger Johnson
    1. USBenjamin Danger Johnson
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    1. PO
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    2. PO
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    1. VO
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      1. POComplex SQL statement feasibility
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      1. VTUpMod
    2. VO
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    3. VO
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    1. COIt would be nice with some table definitions - i feel we are re-modeling here ?
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      1. POComplex SQL statement feasibility
      1. USMike
    2. COIf you add test data for the tables and the expected output for the parameters is easier to rewrite.
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      1. POComplex SQL statement feasibility
      1. USt-clausen.dk
    3. COI can provide some definitions, but I was wondering if this is really a good way to go about solving the problem. Before all our contracts expired by date, so all I had to do was check the end date. But now they can come in a few different flavors, the big one being by hours. Also the function is working perfectly, I just feel like I could have made things simpler.
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      1. POComplex SQL statement feasibility
      1. USBenjamin Danger Johnson
 

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