the question is :
i have a table that contains details, this table is used by users when they registered or update there profile or participate in different exams.
The report I need will have some calculation like aggregate scores .
I would to as if it is better to create new table witch includes the report i need or it's better to work on the same table.
Are you able to provide any further details? What fields are available in the table that you want to query? How do you want to display this information? On a website? For a report?
From what you describe, you need two tables. One table (lets call is 'users') would contain information about each user, and the other would contain the actual exam scores (lets call this table 'results' ).
Each person in the 'user' table has a unique ID number (I'll call it UID) to identify them, and each score in the 'results' table also has the UID of person the score relates to. By including the UID of the user in the 'results' table you can link an infinite number of results (known as a one-to-many relationship).
The 'user' table could look like this:
userUID (UID for each person) | Name | User Details
1 | Barack Obama | President
2 | George Bush | Ex-President
The 'results' table could look like this:
UID for each exam | userUID (UID of the person who look the test) | Score
1 | 1 | 85
2 | 2 | 40
3 | 1 | 82
4 | 2 | 25
I always like to add a UID for things like the exam because it allows you to easily find a specific exam result.
Anyway... a query to get all of the results for Barack Obama would look like this:
SELECT Score From 'results' WHERE userUID = 1
To get results for George Bush, you just change the userUID to 2. You would obviously need to know the UID of the user (userUID) before you ran this query.
Please note that these are VERY basic examples (involving fictional characters ;) ). You could easily add an aggregated score field to the 'user' table and update that each time you add a new result to the 'results' table. Depending upon how your code is set up this could save you a query.
Good luck - Hopefully this helps!
Related
the first is the sectors table that has an id and sector name like this
id | sector
1 | Government
2 | Education
The second is the employee table like this (simplified)
Id | name
1 | sam
2 | tom
Finally I have a sectorMap table (this is used to join the two tables above together) like this
Id | sectorid | employeeid
1 | 1 | 2
2 | 1 | 1
3 | 2 | 2
So in this instance, once I join everything together and view the sectors or each employee, it would show that tom has two sectors (government, education) and sam only has one (government)… hope that makes sense
My question is, within my application, the user has the ability to change these sectors by selecting from a multiple selection dropdown in html. For some reason I thought that by doing an update on duplicate expression would work, however seeing how I have multiple rows of data, I would need to delete all rows within the sectormap table that do not reflect the new selection and contain the selected employees id. What would be the best way of going about that?
For instance, in this case, lets say I open the application and see that tom has two sectors tied to him (government, education) and I only wanted him to have one (government). When I deselect education and select GO. The application returns a list to the server that contains (‘government’). How can I formulate an expression to delete the education sector row from the sectormap table that contains his id?
Your answer is in your question.
1st when you are deselecting education. You will get data of (‘government’). right?
So just invert your query. select those records which is not (‘government’), those are education.
So, education records are you can delete.
Hope this will help you. thanks:)
I have a single flat table containing a list of people which records their participation in different groups and their activities over time. The table contains following columns:
- name (first/last)
- e-mail
- secondary e-mail
- group
- event date
+ some other data in a series of columns, relevant to a specific event (meeting, workshop).
I want to extract distinct people from that into a separate table, so that further down the road it could be used for their profiles giving them a list of what they attended and relevant info. In other words, I would like to have a list of people (profiles) and then link that to a list of groups they are in and then a list of events per group they participated in.
Obviously, same people appear a number of times:
| Full name | email | secondary email | group | date |
| John Smith | jsmith#someplace.com | | AcOP | 2010-02-12 |
| John Smith | jsmith#gmail.com | jsmith#somplace.com | AcOP | 2010-03-14 |
| John Smith | jsmith#gmail.com | | CbDP | 2010-03-18 |
| John Smith | jsmith#someplace.com | | BDz | 2010-04-02 |
Of course, I would like to roll it into one record for John Smith with both e-mails in the resulting People table. I can't rule out that there might be more records for same person with other e-mails than those two - I can live with that. To make it more complex ideally I would like to derive a list of groups, creating a Groups table (possibly with further details on the groups) and then a list of meetings/activities for each group. By linking that I would then have clean relational model.
Now, the question: is there a way to perform such a transformation of data in SQL? Or do I need to write a procedure (program) that would traverse the database and do it?
The database is in MySQL, though I can also use MS Access (it was given to me in that format).
There is no tool that does this automatically. You will have to write a couple queries (unless you want to write a DTS package or something proprietary). Here's a typical approach:
Write two select statements for the two tables you wish to create-- one for users and one for groups. You may need to use DISTINCT or GROUP BY to ensure you only get one row when the source table contains duplicates.
Run the two select statements and inspect them for problems. For example, it's possible some users show up with two different email addresses, or some users have the same name and were combined incorrectly. These will need to be cleaned up in order to proceed. There is great way to do this-- it's more or less a manual process requiring expert knowledge of the data.
Write CREATE TABLE scripts based on the two SELECT statements so that you can store the results somewhere.
Use INSERT FROM or SELECT INTO to populate the tables from your two SELECT statements.
I have two table now:
conference table: id, name
people table: people_id, name
what I want to do
I want to make a new table so that I can get all attend people by conference id but also get all conference a specific man attended by people_id.
what I have thought
make a new table whose columns is all the people's id, and insert each conference as row, if the people shows in conference, we make it 1, otherwise 0. But it's too sparse and difficult to show which people attend a specific conference because we have many columns.
UPDATE
thanks for your comment. Now I create a table like this:
I think it's much better than the table before.
How about this?
A join table called conferences_people.
cp_id | conference_id | people_id
-------+---------------+-----------
1 | 1234 | 1
2 | 1234 | 4
3 | 1234 | 5
Sorry if my question seems unclear, I'll try to explain.
I have a column in a row, for example /1/3/5/8/42/239/, let's say I would like to find a similar one where there is as many corresponding "ids" as possible.
Example:
| My Column |
#1 | /1/3/7/2/4/ |
#2 | /1/5/7/2/4/ |
#3 | /1/3/6/8/4/ |
Now, by running the query on #1 I would like to get row #2 as it's the most similar. Is there any way to do it or it's just my fantasy? Thanks for your time.
EDIT:
As suggested I'm expanding my question. This column represents favourite artist of an user from a music site. I'm searching them like thisMyColumn LIKE '%/ID/%' and remove by replacing /ID/ with /
Since you did not provice really much info about your data I have to fill the gaps with my guesses.
So you have a users table
users table
-----------
id
name
other_stuff
And you like to store which artists are favorites of a user. So you must have an artists table
artists table
-------------
id
name
other_stuff
And to relate you can add another table called favorites
favorites table
---------------
user_id
artist_id
In that table you add a record for every artist that a user likes.
Example data
users
id | name
1 | tom
2 | john
artists
id | name
1 | michael jackson
2 | madonna
3 | deep purple
favorites
user_id | artist_id
1 | 1
1 | 3
2 | 2
To select the favorites of user tom for instance you can do
select a.name
from artists a
join favorites f on f.artist_id = a.id
join users u on f.user_id = u.id
where u.name = 'tom'
And if you add proper indexing to your table then this is really fast!
Problem is you're storing this in a really, really awkward way.
I'm guessing you have to deal with an arbitrary number of values. You have two options:
Store the multiple ID's in a blob object in JSON format. While MySQL doesn't have JSON functions built in, there are user defined functions that will extract values for you, etc.
See: http://blog.ulf-wendel.de/2013/mysql-5-7-sql-functions-for-json-udf/
Alternatively, switch to PostGres
Add as many columns to your table as the maximum number of ID's you expect to have. So if /1/3/7/2/4/8/ is the longest entry, have 6 columns in your table. Reason this is bad: you'll have sparse columns that'll unnecessarily slow your tables.
I'm sure you could write some horrific regex to accomplish the task, but I caution on using complex regex's on enormous tables.
I am doing a project in MS Access 2007 where I am going to count the number of absences of each student. This will be the table:
name of student | absent1 | absent2 | absent3 | absent4 | absent5 | total
ryan llorcanuada| 05-7-12 | 05-8-12 | 05-9-12 |________ | _______ | 3
The maximum number of absences of each student is 5. So based from the table, the student got only 3 absences and the remaining fields are blank. Supposedly, the table will display 3 in the total field. How am I going to do that? What if the student has no absences?
So, is the question "What is the best way to design a table to store absences?" or is it "Given the following table, how can you calculate the number of absences a student has?"
I ask because the table as shown is a very bad way to structure your database. To solve the problem with this structure, you are probably going to have to use a series of IIF functions. Please try something and post what you've tried, then people can help you fix your answer.