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I'm a bit unsure what is best way to tackle one requirement that I have on my project (Laravel API and Angular UI). So I have one pretty straightforward task. I need to create database schema for members and their subscription status for months in selected year.
I need to keep this as simple as possible, because this is a very simple admin app, where admin user will manually mark paid status for each member when they pay, so there is nothing special or advanced here. On UI it should look like this:
So basically every year members can pay membership for every month in that year.
Note: x means member payed membership for that month.
From database standpoint I'm thinking and trying to decide about something like this:
Note: membership and another_membership are tables that I'm consider to use, I will chose one of them, based on suggestions
So basically the idea behind this is pretty simple, every time member pays, membership table will be updated with date and member id, and that way I will have all payments for every member.
Because of UI from first picture I have few problems that I'm not really sure how to approach.
In order to generate bootstrap table from first image I'm thinking something like, for example if I want to get all memberships for year 2018 from certain selection I will do something like:
Select * from member m left join membership ms on m.id = ms.member_id where date >= 01-01-2018 and date <= 01-31-2018 and m.selection_id = 1
But I'm still unsure what is best way to map members each month status. I'm thinking maybe to group all dates from membership table and then somehow to generate this table
Anyone have any suggestions on this? Should I use membership table or another_membership table? Should I do mapping (members and months statuses) on UI or API side? Any other suggestion? Someone told me that it might be a "good" idea to create simple table with member_id, year, and all 12 months as attributes and just store true/false for each month there. Something like this:
Also one thing that bothers me, is it good idea maybe to first get all members, and then get all data from membership table based on member ids, so for example if I have pagination of 20 members I will make db call like this:
Get page 0 with 20 members
select * from membership m where m.member_id in (list_of_ids)
You do not want to store membership information in columns. Either membership or another_membership are fine -- they store the values in rows.
Which to choose? That is really up to you. For a general application, I would go for something like:
MemberShipId
EffDate -- from date
EndDate -- to date
PaymentDate
. . . other information
You are set on the memberships being for one month periods, so having either a single date (say the first of the month) or splitting out the columns into (year and month) are fine.
What #GordonLinoff writes is how I would structure the database.
The next thing you probably need is a way of pivoting your rows to columns; you probably end up with a query that produces output along the lines of:
UserName Month Member
---------------------
Tom Jan18 null
Tom Feb18 1
.....
This question shows you how to convert that into the rows your front-end cares about.
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I'm creating a function that retrieves records based on several different fields and then stores those records so we can query them later.
When querying the records, we're selecting a record to be used elsewhere if it matches the requirements of another set of fields/criteria.
For example:
Returning employee records so that one of them can be selected for a new position (management maybe?) based on fields such as skill set, location, and so on...
The problem
Say I loop through these stored records (in an array or something similar) and I check if the first employee in the array is suitable for the position, then find out they are, so then add them to the position, I'm neglecting the other x amount of employees that have been stored. I feel like this would be an issue because it might turn out that the order in which someone is stored might determine the likelyhood they are chosen for the position.
I thought this might be solved by creating a sorting function to sort the stored records based on the employers preferences (location, salary, availability,...), although I'm not sure how to implement this.
I'm wondering if there is any built in MySQL functions that would help sort the records based on something?
This might be something I might have to figure out on my own, but I thought I'd ask just in case there was anything useful I could use.
I hope the question was clear. If not, please comment below.
Just thinking out loud - won't sorting create the same issue you are trying to avoid - unless you can come up with a weighted score...
create table as employees_to_consider as
select e.*,
availability_score*availablity_factor
+ salary_score*salary_factor
+ location_score*location_factor as weighted_score
from employees e
where -- whatever your criteria is for selection here
order by weighted_score
The real task is deciding how to determine the score for each factor and what the appropriate weight should be.
For example, salary score can be determined by taking the ratio of what the employee is willing to work for by the target. If they match, it can be scored as 50. The number can be increased by the amount the employee is willing to work under the target and decreased by an amount they are over. Salary is pretty important so the factor might be 33%.
Similarly, if the employee lives with 15 minutes, then they can be scored at 75, within 30 at 50, over 30 25. Location is not as important as salary so it is scored at 10%.
Hopefully, you will be able to assign meaningful scores and factors to each measure.
I am currently working on a simple booking system and I need to select some ranges and save them to a mysql database.
The problem I am facing is deciding if it's better to save a range, or to save each day separately.
There will be around 500 properties, and each will have from 2 to 5 months booked.
So the client will insert his property and will chose some dates that will be unavailable. The same will happen when someone books a property.
I was thinking of having a separate table for unavailable dates only, so if a property is booked from 10 may to 20 may, instead of having one record (2016-06-10 => 2016-06-20) I will have 10 records, one for each booked day.
I think this is easier to work with when searching between dates, but I am not sure.
Will the performance be noticeable worse ?
Should I save the ranges or single days ?
Thank you
I would advise that all "events" go into one table and they all have a start and end datetime. Use of indexes on these fields is of course recommended.
The reasons are that when you are looking for bookings and available events - you are not selecting from two different tables (or joining them). And storing a full range is much better for the code as you can easily perform the checks within a SQL query and all php code to handle events works as standard for both. If you only store one event type differently to another you'll find loads of "if's" in your code and find it harder to write the SQL.
I run many booking systems at present and have made mistakes in this area before so I know this is good advice - and also a good question.
This is too much for a comment,So I will leave this as an answer
So the table's primary key would be the property_id and the Date of a particular month.
I don't recommend it.Because think of a scenario when u going to apply this logic to 5 or 10 years system,the performance will be worse.You will get approximately 30*12*1= 360 raws for 1 year.Implement a logic to calculate the duration of a booking and add it to table against the user.
CURRENT FUNCTIONALITY:
In my financial/budgeting app, the current functionality allows a user to add a recurring budget category that will appear in each month's budget. It does this by allowing a user to select a "recurring" option from a dropdown, which makes 2 additional dropdowns appear, one with a beginning month and one with an ending month. When the category is recurring, it writes the beginning month and the ending month to the database (diagram below).
DESIRED FUNCTIONALITY:
The problem with the current design is that I want the user to be able to delete one (or more) month from the recurring months. So lets say I set up a recurring category in January for the entire year. Then I get to May and I want that category not to appear for that month. If I delete the category, it currently deletes it for all months, past and present. I need it to have the option to only delete only the desired month(s).
I'm not sure how to accomplish this, and I thought maybe someone has a good idea. Maybe my database structure is off? In the interest of normalization, I didn't want to just add a column for each month or anything like that.
Rather than storing the recurrence formula, IMHO it would be best to store the actual months in a many-to-many relationship:
categories
----------
id
name
months
------
id
category_months
---------------
cat_id
month_id
When a user enters a recurrence formula, it will create the relationships. Then they will be freely able to remove months one at a time if necessary.
I have two queries ultimately I think they will be in the same context of the other but in all. I have a user database that I want to pull out for tracking records based on hour. Example registrations per hour. But in this registrations per hour I want to have the query to dump results by hour increments (or weeks, or months) ie: 1,000 regitrations in november, 1,014 in december and so on, or similar for weeks hours.
I also have a similar query where I want to generate a list of states with the counts next to them of how many users I have per state.
My issue is, I'm thinking I think to one dimensionally currently cause the best idea I can think of at the moment is making in the case of the states 50 queries, but I know thats insane, and there has to be an easier way thats less intense. So thats what Im hoping someone from here can help me with, by giving me a general idea. Cause I don't know which is the best course of action for this currently.. be it using distinct, group_by or something else.
Experiment a bit and see if that doesn't help you focus on the question a bit more.
Try selecting from your registrations per hour table and appending the time buckets you are interested in to the select list.
like this:
select userid, regid, date_time, week(date_time), year(date_time), day(date_time)
from registraions;
you can then roll up and count things in that table by using group by and an aggregate function like this:
select count(distinct userid), year(date_time)
from registraions
group by year(date_time)
Read about about date time functions:
MySQL Date Time Functions
Read about aggregate functions"
MySQL Group By
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I need to implement a mechanism with the following abilities:
Add new users
Delete a user
Enable a user
Disable a user
And also let the administrator to select a period of time and then show which users were:
Available in the system at that period
Enabled
Disabled
The result should be for that exact period of time.
Note: A user might be enabled or disabled several times and I need to keep track of every single change. So, if the user is disabled between the March 1th and April 2nd, it should not be appear in the results if the administrator querying a time period between March 1th up to April 2nd, but it should be included in the results if the administrator querying any other period of time.
Also the tricky part is to contain the usesr who has been added, deleted, enabled or disabled before the period that administrator querying.
I don't have any set up for now, so I'm pretty up for any idea. Actually I'm thinking of a mechanism like a log which you can query that later, but it should be really fast because I need to use it in many places.
Also I prefer to do everything in a single MySQL Query, however the PHP combination/interaction is also okay.
Per commentary, look into Slowly Changing Dimensions:
http://en.wikipedia.org/wiki/Slowly_changing_dimension
An additional top, having implemented this a few times myself. Personally, I've found it better to have two sets of tables, rather than a single one.
Think of the main one as a normal table with an extra rev (for revision_id) field:
id, rev, field1, field2
rev is a foreign key to the revisions table:
id, rev, field1, field2, start_date, end_date
And if you ever use Postgres to implement it, I'd advise to look into the tsrange type instead of two separate start_date and end_date types.
The main table vs history tables makes "normal" queries perform better and much easier to index.