I would like to ask because this makes me bald since last week.
I have to make a complaint form for stores for our products.
We have some contractors and they have their own stores/resellers.
Each reseller has own link to the same form with just a list of stores related to only one contractor.
Already I have multiple tables (as many as I have contractors) with stores inside each.
I wanted to upgrade script with some features and decided to rebuild database.
But have a question - better is to have one table with all stores from all contractors or to have multiple tables for each contractor separately? What is the safest option.
I know that if database will be compromised - all tables will be visible, so all in all there is no difference.
Just thinking - based on your better than mine experience:
- better is to switch "tablename" in MySQL connection related to URL (like I already have)
or
- better is to have one "tablename" with i.e. "contractor" column to select only stores related to contractor?
I will be thankful for your opinion and explanations (if you can) - what and why is the best.
Related
I am a developer and have never worked on DB before (designing a DB). I am designing a database for an employee management system which is a Node.js + Express application using MySQL as its DB.
I already have the required tables, columns sorted out but there are still few unknowns I am dealing with. This is my plan so far and I need your input on it.
The end users using this application will be small - mid size companies. The companies won't be sharing the tables in the database. So if there is a table named EmployeeCases I plan to create a new EmployeeCases table for each existing company or a new one who signs up for this application. I am planning to name the table as EmployeeCases_989809890 , where "989809890" will be the company id (or customer id). So if we have 3-4 companies who signed up for us, then all the tables (at least the ones which a company uses) will be recreated and named as TableName_CompanyId. My questions, is this a good way to go? Is there a better way?
All the employee's data is held by the Employee table, including their login and password. Now each Employee table in DB will be named as Employee_CompanyId (as per my plan above). My question is, when an employee logs in, how will I know which Employee table to query to? Or should I remove the login from the Employee table and create a universal Users table where all the employees will be stored? The Users table will also have the CompanyId as one of its column and I will read the CompanyId from there which will be used to query other tables.
Any reference, website or blogs on this type of design will be appreciated.
Thanks.
I don't recommend this approach, I think you should either:
A) Put all the information in the same tables and have a companyId column to sort them out
OR
B) Have separate databases for each company and use the appropriate database using the code.
The thing is, with your approach, you'll have a hard time maintaining your application if you have multiple copies of the same table with different names. If you decide to add a column to one of the tables, for instance, you will have to write as many SQL scripts as you have table instances. You'll also have a bad time with all of your unique identifiers.
Here are some advantages/disadvantages of each design:
A) Put all the information in the same tables and have a compagnyId column to sort them out
Advantages:
Simplest
Allow usage of foreign key / constraints
Great for cross / client data extraction
Disadvantages:
Not portable (a client can't just leave with his/her data)
Can be perceived as less secure (I guess you can make the case both ways)
More likely to have huge tables
Does not scale very well
B) Have separate databases for each company and use the appropriate database using the code.
Advantages:
Portable
Can be perceived as more secure
Disadvantages:
Needs more discipline to keep track of all the databases
Needs a good segregation of what's part of your HUB (Your application that tracks which client access which database) and that's part of your client's database.
You need a login page by company (or have your clients specify the company in a field)
An example of an application that uses this "two-step login" is Slack, when you sign-in you first enter your team domain THEN your user credentials.
I think Google Apps for Work as the same approach. Also, I think most CRM I worked with has a separate database for their clients.
Lastly, I'd like to direct you to this other question on stackoverflow that links to an interesting example.
You shouldn't split your tables just because companies won't share their information. Instead, you should have a companyId column in each table and access to the relevant data for each query. This should be implemented in your backend
I’m currently developing an Application for Win, Linux Mac. The Purpose of the Application is that multiple users are able create Projects based on a single Article. Every Article has up to 15 different Fields/Options (could also be more in future). The Fields of the Article should be changeable so I should be able to add, edit or remove them.
Fields I want to store:
Numbers
Texts (mostly options [1 Word], sometimes Comments [some sentences])
Path/Links to Files
What I want to do with the dB:
load all projects of a user at login
add, edit, remove, delete single projects
set a lock on projects (because multiple people are operating one user-account at the same time and therefore they may not be allowed to edit a project at the same time so if one starts editing it should be locked until he's saving, channelling or time-out)
What is the best way to manage this kind of Data?
Should I create a Table for each user and only make a ID Column and one where all the Values of the all the fields (who are merged to one big string)?
Should I create Tables for every Project and make Columns for every Field/Option and also one for the user / owner?
Or are there any other possibility’s?
If you don't know what you are going to store, then I doubt whether a relational database is the best option for you. Maybe a document store/noSQL database is a better decision, because you can just store documents (usually in the form of Json objects) that can have all kinds of additional fields.
A couple of such databases to look at are MongoDB, Cassandra, ElasticSearch, but you can find a big list on Wikipedia.
I hope someone can help me with this:
I have a simple query combining a list of names and basic details with another table containing more specific information. Some names will necessarily appear more than once and arbitrary distinctions like "John Smith 1" and "John Smith 2" are not an option, so I have been using an autonumber to keep the records distinct.
The problem is that my query is creating two records for each name that appears more than once. For example, there are two clients named 'Sophoan', each with a different id number, and the query has picked up each one twice resulting in four records (in total there are 122 records when there should only be 102). 'Unique values' is set to 'yes'.
I've researched as much as I can and am completely stuck. I've tried to tinker with sql but it always comes back with errors, I presume because there are too many fields in the query.
What am I missing? Or is a query the wrong approach and I need to find another way to combine my tables?
Project in detail: I'm building a database for a charity which has two main activities: social work and training. The database is to record their client information and the results of their interactions with clients (issues they asked for help with, results of training workshops etc.). Some clients will cross over between activities which the organisation wants to track, hence all registered clients go into one list and individual tables spin of that to collect data for each specific activity the client takes part in. This query is supposed to be my solution for combining these tables for data entry by the user.
At present I have the following tables:
AllList (master list of client names and basic contact info; 'Social Work Register' and 'Participant Register' join to this table by
'Name')
Social Work Register (list of social work clients with full details
of each case)
Social Work Follow-up Table (used when staff call social work clients
to see how their issue is progressing; the register has too many
columns to hold this as well; joined to Register by 'Client Name')
Participants Register (list of clients for training and details of
which workshops they were attended and why they were absent if they
missed a session)
Individual workshop tables x14 (each workshop includes a test and
these tables records the clients answers and their score for each
individual test; there will be more than 20 of these when the
database is finished; all joined to the 'Participants Register' by
'Participant Name')
Queries:
Participant Overview Query (links the attendance data from the 'Register' with the grading data from each Workshop to present a read-only
overview; this one seems to work perfectly)
Social Work Query (non-functional; intended to link the 'Client
Register' to the 'AllList' for data entry so that when a new client
is registered it creates a new record in both tables, with the
records matched together)
Participant Query (not yet attempted; as above, intended to link the
'Participant Register' to the 'AllList' for data entry)
BUT I realised that queries can't be used for data entry, so this approach seems to be a dead end. I have had some success with using subforms for data entry but I'm not sure if it's the best way.
So, what I'm basically hoping to achieve is a way to input the same data to two tables simultaneously (for new records) and have the resulting records matched together (for new entries to existing records). But it needs to be possible for the same name to appear more than once as a unique record (e.g. three individuals named John Smith).
[N.B. There are more tables that store secondary information but aren't relevant to the issue as they are not and will not be linked to any other tables.]
I realised that queries can't be used for data entry
Actually, non-complex queries are usually editable as long as the table whose data you want to edit remains 'at the core' of the query. Access applies a number of factors to determine if a query is editable or not.
Most of the time, it's fairly easy to figure out why a query has become non-editable.
Ask yourself the question: if I edit that data, how will Access ensure that exactly that data will be updated, without ambiguity?
If your tables have defined primary keys and these are part of your query, and if there are no grouping, calculated fields (fields that use some function to change or test the value of that field), or complex joins, then the query should remain editable.
You can read more about that here:
How to troubleshoot errors that may occur when you update data in Access queries and in Access forms
Dealing with Non-Updateable Microsoft Access Queries and the Use of Temporary Tables.
So, what I'm basically hoping to achieve is a way to input the same data to two tables simultaneously (for new records) and have the resulting records matched together (for new entries to existing records). But it needs to be possible for the same name to appear more than once as a unique record (e.g. three individuals named John Smith).
This remark actually proves that you have design issues in your database.
A basic tenet of Database Design is to remove redundancy as much as possible. One of the reasons is actually to avoid having to update the same data in multiple places.
Another remark: you are using the Client's name as a Natural Key. Frankly, it is not a very good idea. Generally, you want to make sure that what constitutes a Primary key for a table is reliably unique over time.
Using people's names is generally the wrong choice because:
people change name, for instance in many cultures, women change their family name after they get married.
There could also have been a typo when entering the name and now it can be hard to correct it if that data is used as a Foreign Key all in different tables.
as your database grows, you are likely to end up with some people having the same name, creating conflicts, or forcing the user to make changes to that name so it doesn't create a duplicate.
The best way to enforce uniqueness of records in a table is to use the default AutoNumber ID field proposed by Access when you create a new table. This is called a Surrogate key.
It's not mean to be edited, changed or even displayed to the user. It's sole purpose is to allow the primary key of a table to be unique and non-changing over time, so it can reliably be used as a way to reference a record from one table to another (if a table needs to refer to a particular record, it will contain a field that will hold that ID. That field is called a Foreign Key).
The names you have for your tables are not precise enough: think of each table as an Entity holding related data.
The fact that you have a table called AllList means that its purpose isn't that well-thought of; it sounds like a catch-all rather than a carefully crafted entity.
Instead, if this is your list of clients, then simply call it Client. Each record of that table holds the information for a single client (whether to use plural or singular is up to you, just stick to your choice though, being consistent is hugely important).
Instead of using the client's name as a key, create an ID field, an Autonumber, and set it as Primary Key.
Let's also rename the "Social Work Register", which holds the Client's cases, simply as ClientCase. That relationship seems clear from your description of the table but it's not clear in the table name itself (by the way, I know Access allows spaces in table and field names, but it's a really bad idea to use them if you care at least a little bit about the future of your work).
In that, create a ClientID Number field (a Foreign Key) that will hold the related Client's ID in the ClientCase table.
You don't talk about the relationship between a Client and its Cases. This is another area where you must be clear: how many cases can a single Client have?
At most 1 Case ? (0 or 1 Case)
exactly 1 Case?
at least one Case? (1 or more Cases)
any number of Cases? (0 or more Cases)
Knowing this is important for selecting the right type of JOIN in your queries. It's a crucial part of the design assumptions when building your database.
For instance, in the most general case, assuming that a Client can have 0 or more cases, you could have a report that displays the Client's Name and the number of cases related to them like this:
SELECT Client.Name,
Count(ClientCase.ID) AS CountOfCases
FROM Client
LEFT JOIN ClientCase
ON Client.ID = ClienCase.ClientID
GROUP BY Client.Name
You've described your basic design a bit more, but that's not enough. Show us the actual table structures and the SQL of the queries you tried. From the description you give, it's hard to really understand the actual details of the design and to tell you why it fails and how to make it work.
Being new to relational database design, I am trying to clarify one piece of information to properly design this database. Although I am using Filemaker as the platform, I believe this is a universal question.
Using the logic of ideally having all one to many relationships, and using separate tables or join tables to solve these.
I have a database with multiple products, made by multiple brands, in multiple product categories. I also want this to be as scale-able as possible when it comes to reporting, being able to slice and dice the data in as many ways as possible since the needs of the users are constantly changing.
So when I ask the question "Does each Brand have multiple products" I get a yes, and "Does each product have multiple brands" the answer is no. So this is a one to many relationship, but it also seems that a self-join table might give me everything that I need.
This methodology also seems to go down a rabbit hole for other "product related" information such as product category, each product is tied to one product category, but only one product category is related to a product.
So I see 2 possibilities, make three tables and join them with primary and foreign keys, one for Brand, one for Product Category, and one for Products.
Or the second possibility is to create one table that has the brand and product category and product info all in one table (since they are all product related) and simply do self-joins and other query based tables to give me the future reporting requirements that will be changing over time.
I am looking for input from experiences that might point me in the right direction.
Thanks in advance!
Could you ever want to store additional information about a brand (company URL, phone number, etc.) or about a product category (description, etc.)?
If the answer is yes, you definitely want to use three tables. If you don't, you'll be repeating all that information for every single item that belongs to the same brand or same category.
If the answer is no, there is still an advantage to using three tables - it will prevent typos or other spelling inconsistencies from getting into your database. For example, it would prevent you from writing a brand as "Coca Cola" for some items and as "Coca-Cola" for other items. These inconsistencies get harder and harder to find and correct as your database grows. By having each brand only listed once in it's own table, it will always be written the same way.
The disadvantage of multiple tables is the SQL for your queries is more complicated. There's definitely a tradeoff, but when in doubt, normalize into multiple tables. You'll learn when it's better to de-normalize with more experience.
I am not sure where do you see a room for a self-join here. It seems to me you are saying: I have a table of products; each product has one brand and one (?) category. If that's the case then you need either three tables:
Brands -< Products >- Categories
or - in Filemaker only - you can replace either or both the Brands and the Categories tables with a value list (assuming you won't be renaming brands/categories and at the expense of some reporting capabilities). So really it depends on what type of information you want to get out in the end.
If you truly want your solution to be scalable you need to parse and partition your data now. Otherwise you will be faced with the re-structuring of the solution down the road when the solution grows in size. You will also be faced with parsing and relocating the data to new tables. Since you've also included the SQL and MySQL tags if you plan on connecting Filemaker to an external data source then you will definitely need to up your game structurally.
Building everything in one table is essentially using Filemaker to do Excel work and it won't cut it if you are connecting to SQL, MySQL, etc.
Self join tables are a great tool. However, they should really only be used for calculating small data points and should not be used as pivot points or foundations for your reporting features. It can grow out of control as time goes on and you need to keep your backend clean.
Use summary and sub-summary reporting features to slice product based data.
For retail and general product management solutions, whether it's Filemaker/SQL/or whatever the "Brand" or "Vendor" is it's own table. Then you would have a "Products" table (the match key being the "Brand ID").
The "Product Category" field should be a field in the "Products" table. You can manage the category values by building a standard value list or building a value list based on a "Product Category" table. The second scenario is better for long term administration.
I know this question has been asked and answered many times, and I've spent a decent amount of time reading through the following questions:
Database table structure for user settings
How to handle a few dozen flags in a database
Storing flags in a DB
How many database table columns are too many?
How many columns is too many columns?
The problem is that there seem to be a somewhat even distribution of supporters for a few classes of solutions:
Stick user settings in a single table as long as it's normalized
Split it into two tables that are 1 to 1, for example "users" and "user_settings"
Generalize it with some sort of key-value system
Stick setting flags in bitfield or other serialized form
So at the risk of asking a duplicate question, I'd like to describe my specific scenario, and hopefully get a more specific answer.
Currently my site has a single user table in mysql, with around 10-15 columns(id, name, email, password...)
I'd like to add a set of per-user settings for whether to send email alerts for different types of events (notify_if_user_follows_me, notify_if_user_messages_me, notify_when_friend_posts_new_stuff...)
I anticipate that in the future I'd be infrequently adding one off per-user settings which are mostly 1 to 1 with users.
I'm leaning towards creating a second user_settings table and stick "non-essential" information such as email notification settings there, for the sake of keeping the main user table more readable, but is very curious to hear what expects have to say.
Seems that your dilemma is to vertically partition the user table or not. You may want to read this SO Q/A too.
i'm gonna cast my vote for adding two tables... (some sota key-value system)
it is preferable (to me) to add data instead of columns... so,
add a new table that links users to settings, then add a table for the settings...
these things: notify_if_user_follows_me, notify_if_user_messages_me, notify_when_friend_posts_new_stuff. would then become row insertions with an id, and you can reference them at any time and extend them as needed without changing the schema.