for example i have table users, which have 3 fields:
id - login - password
---------------------
1 | john | *****
2 | jack | *****
3 | jane | *****
now i want that each user could have his own settings.
So, do i need to create three different tables, like
user_N_settings:
id | key | value
-------------------------
1 | save_data | True
or i should create one big table for all users instead?
users_settings:
id | key | value | user_id
---------------------------------------------
1 | save_data | True | 2
2 | some_opt | False | 3
One table for all users. A table per user would be very wrong.
One table. If all the setting values are of the same type then it may make sense to create one row per setting. If the attributes are all very different then create one column per setting.
Related
I'm trying to design a database that allows for filtering according to if a specific resource fills certain categories. I've gotten to the point where I can input data that seems to be how it should be filled out but I'm not sure how I should pull it out again.
The main resource table looks like this:
Table1 - resources
| resourceID | AutoNum |
| title | short text |
| author | short text |
| publish date | date |
| type | short text |
Table2 - Department Categories
| ID | AutoNum |
| 1 | Yes/No |
| 2 | Yes/No |
| fID| Number |
Table3 - Categories
| ID | AutoNum |
| cat | Yes/No |
| dog | Yes/No |
| bird | Yes/No |
| fID | Number |
I have built a form where you can fill in items to the resource ID, and at the same time check off the Yes/No boxes in tables 2 & 3.
I'm trying to use the primary key ID from table 1 and copy it into the table 2 & 3 with referential integrity to cascade deletes, updates. Which I think is the right way to do this.
Currently, I've learnt that I can implement a search function for the columns in table 1, this seems to work fine. However I am stuck with applying the relevant columns in table 2 and 3 as filters.
apply search>
[X] - Cats
Should only return records from table 1 where in table 3 the relevant column has a tick in the Yes/No box.
I hope I have explained this properly, very new to Access and databases so if you need clarity, don't mind offering.
I have multiple employee groups in my project. Based on the selection of different employee group,submission form fields will differ in the view. If the fields are static then it is easy to do the CRUD operations. I need to create the fields dynamic in nature. I must be able to configure the form fields in SQL server table.For employee Group 1, 5 fields, for Group 2, 6 fields etc. If i want to add new field to any of the group in future also it should work. How can i achieve this?
Thanks
Have you considered using many-to-many relationship between tables Employees and Fields. Something like this:
You'll have a table that holds the list of all possible fields (first name, last name and etc). Then to connect the Employees table and the Fields table with many-to-many relationship you'll need some kind of table (EmployeesFields). Table EmployeesFields holds the value for the each field that employee has.
For example:
EMPLOYEES
+----+------------------+
| Id | CreatedAt |
+----+------------------+
| 1 | 02.08.2017 11:21 |
+----+------------------+
FIELDS
+----+-----------+------------------+
| Id | Name | CreatedAt |
+----+-----------+------------------+
| 1 | FirstName | 02.08.2017 11:24 |
| 2 | LastName | 02.08.2017 11:26 |
+----+-----------+------------------+
EMPLOYEESFIELDS
+------------+---------+-------+------------------+
| EmployeeId | FieldId | Value | CreatedAt |
+------------+---------+-------+------------------+
| 1 | 1 | John | 02.08.2017 11:34 |
| 1 | 2 | Doe | 02.08.2017 11:39 |
+------------+---------+-------+------------------+
I think this is the most simple solution. It just shows the basic idea. Modify it to fit your needs.
Let's assume we have application with pages, posts and events. With each part of this application we want to have comments. Now let's take a look into tables for our DB.
1. One comment table, object and object_id as foreign key
Page/Post/Event has many comments, foreign key object, object_id
comments table
+-------------+-------------+-------------+-------------+
| id | object | object_id | text |
=========================================================
| 1 | Page | 1 | Comment 1 |
+-------------+-------------+-------------+-------------+
| 2 | Post | 1 | Comment 2 |
+-------------+-------------+-------------+-------------+
| 3 | Event | 1 | Comment 3 |
+-------------+-------------+-------------+-------------+
2. Multiple comments tables
Page (Post, Event) has many page comments, foreign key page_id
page_comments table
+-------------+-------------+-------------+
| id | page_id | text |
===========================================
| 1 | 1 | Comment 1 |
+-------------+-------------+-------------+
post_comments table
+-------------+-------------+-------------+
| id | post_id | text |
===========================================
| 1 | 1 | Comment 2 |
+-------------+-------------+-------------+
event_comments table
+-------------+-------------+-------------+
| id | event_id | text |
===========================================
| 1 | 1 | Comment 3 |
+-------------+-------------+-------------+
I have used specific example, but this can apply to any other 1:N tables or even with M:N (tags), but for simple showcase, this should be good.
We should discuss
Performance concerns
Design pros and cons
Initial thoughts
case 1 means less tables in DB, easier to read, reusable application code
case 1 is better when doing query on all comments (would have to use union at case 2)
case 2 is better in regards of normalization (3NF)
case 2 is easier to backup (dump) parts of the system, e.g. pages itself with their comments
case 2 should be better with performance because less rows => faster
I am developing a database system. It is for a canoe club. The part of the database I am stuck on is assigning a member of the canoe club to a canoe qualification course when/if they undertake one.
Here is a stripped down view of my tables:
members
-------------------------------------
| memberID | first_name | last_name |
-------------------------------------
| 1 | John | Jacobs |
| 2 | Ellie | Graham |
| 3 | Paul | Abbot |
-------------------------------------
course_info
---------------------------------------
| courseID | course_name | Instructor |
---------------------------------------
| 1 | BCU Level 1 | Ryan Adams |
| 2 | BCU Level 2 | Ryan Adams |
| 3 | BCU Level 3 | Ryan Adams |
| 4 | BCU Level 4 | Ryan Adams |
| 5 | BCU Level 5 | Ryan Adams |
---------------------------------------
course_progress
-------------------------------
| memberID | courseID | grade |
-------------------------------
| 1 | 2 | 4 |
| 1 | 4 | 5 |
| 2 | 1 | 3 |
| 3 | 5 | 2 |
-------------------------------
So as you can see,course_progress displays the courses a member has undertaken as well as their grade by using memberID and courseID.
Firstly is that the correct (or a correct) way of doing this? If so, here is my problem...
Using Access I want to create a form that allows me to assign a member to a course. So I have a combo box that lists all of the members and another that lists all of the courses. As well as a box for inputting the grade.
When I fill in this form it only adds the grade to the course_progress table. I feel as though this is the case because I am using fields from different tables in the combo box. The other solution that while works is less than ideal is to have memberID and courseID in the combo box. I believe that works as I am using fields from the table I am trying to add to. However it is not user friendly as ID's are meaningless to a user.
So I want to be able to select the member name and course name from the combo box and add them to the course_progress table as well as the grade.
Any guidance would be great.
Thanks.
Firstly, is your form bound to the course_progress table., and are the two combo boxes bound to the memberID and courseID fields of the progress table.
Secondly, what have you used as the query for each combo box. You should be querying the members table. Assuming you do, you will have 3 columns, the first being the member ID and that should be the "bound column" in the combo box properties. in the format section you will need to give column widths, and I would give the memberID column a width of 0 so it doesn't show. But you should say you want to display 3 columns (so you get firstname and last name in the combo box.
Do the same for the course combo box.
I'm new in DataBases at all and have some difficulties with setting relationships between 3 tables in MS Access 2013.
The idea is that I have a table with accounts info, a table with calls related to this accounts and also one table with all the possible call responses. I tried different combinations between them but nothing works.
1st table - Accounts : AccountID(PK) | AccountName | Language | Country | Email
2nd table - Calls : CallID(PK) | Account | Response | Comment | Date
3rd table - Responses: ResponseID(PK) | Response
When you have a table, it usually has a Primary Key field that is the main index of the table. In order for you to connect it with other tables, you usually do that by setting Foreign Key on the other table.
Let's say you have your Accounts table, and it has AccountID field as Primary Key. This field is unique (meaning no duplicate value for this field).
Now, you have the other table called Calls and you have a Foreign Key field called AccountID there, which points to the Accounts table.
Essentially you have Accounts with the following data:
AccountID| AccountName | Language | Country | Email
1 | FirstName | EN | US | some#email.com
2 | SecondName | EN | US | some#email.com
Now you have the other table Calls with Many calls
CallID(PK) | AccountID(FK) | ResponseID(FK) | Comment | Date
1 | 1 | 1 | a comment | 26/10
2 | 1 | 1 | a comment | 26/10
3 | 2 | 3 | a comment | 26/10
4 | 2 | 3 | a comment | 26/10
You can see the One to Many relationship: One accountID (in my example AccountID=1) to Many Calls (in my example 2 rows with AccountID=1 as foreign keys, rows 1 & 2) and AccountID=2 has also 2 rows of Calls (rows 3 and 4)
Same goes for the Responses table
Using this table structure:
Accounts : AccountID(PK) | AccountName | Language | Country | Email
Calls : CallID(PK) | AccountID(FK) | ResponseID(FK) | Comment | Date
Responses: ResponseID(PK) | Response
Accounts.AccountID is referenced by Calls.AccountID. 1:n – many calls for one account possible, but each call concerns just one account.
Responses.ResponseID is referenced by Calls.ResponseID. 1:n – many calls can get the same response from the prepared set, but each call gets exactly one of them.
To actually define the Relationships in Access, open the Relationships window...
... then follow the detailed instructions here:
How to define relationships between tables in an Access database