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I have two tables that should somehow be associated. Let's call them table_a and
table_b. A row in table_a can be associated with multiple rows in table_b, and the same goes the other way around. How could I achieve this? Should I use a pivot table?
Both tables have an auto-incrementing id-column.
What you're looking for is called a many-to-many relationship (a given user has zero or more games, a given game has zero or more users). This is typically handled with a "mapping table", e.g. USER_GAMES which has a user_id and a game_id, uniqueness is on the combination of these. http://www.joinfu.com/2005/12/managing-many-to-many-relationships-in-mysql-part-1/ has some good details.
As it is a many to many relationship, an intersection table with the user ID & game ID would be the best. Otherwise you would have to parse the list of game ID's stored in the user table and that would cause performance issues.
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I have multiple products/environment, like Google has drive, docs etc.
One common Auth server is there which will contain users table.
But I have roles table related to each product, which contains roles for user for respective product.
Now how to manage this roles table?
I have following ways to do this, which one is better and why?
Create common table roles in main schema, and have product ID to link the records in table.
Have different table in same schema with prefix product_name. Eg. prod1_roles, prod2_roles.
Have different schema in same database, for Eg. product1 schema contains product1 roles table and so on.
Which of the above approach should I go with? Creating different database for 1 table is not feasible for me. So I want to go with any one of above or any other better approach will be appreciated.
If all your tables could have the same columns, is better to have just one, in a central schema, using an product_id. You will use the same pattern for login all your users at different products. This make your security layer easyer to control. And this is an important feature.
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I'm trying to find the best solution for my needs. I have a budgeting application that each user will have their own budget which will include potentially hundreds or thousands of budget entries. Initially I thought I would have a table for the users and basic info, and then each user would have their own sql table with all of their budget items held within. However, if the user list grows to hundreds or thousands then I would have a large amount of tables since each user would have their own. I also considered a single table to hold everyone's budget entries but I'm not sure that's the correct solution either.
Any advice? Thank you in advance
I think a single table that holds all the budget entries, with a primary key that's referenced by a foreign key in the "users" table, is a good way to go. You can always use something like select * from users u join budgets b on u.userID = b.userID where userID = xxx to get the budget items for a particular user.
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I have two tables in my db:
Marketers:
Id, Username, Password, Email
Stores:
Marketer Id, 1 Store, 2 Store, 3 Store, 4 Store, ...., 10 store
there is the names of 10 stores for every marketer in Stores table.
So there is a one to one relationship between these two tables. right?
I'm wondering if it would be better to just combine these two tables or not.
I wan't to send a lot of query for the second table (Stores tables). so I though this would be better if I separate these two cause I rarely need the information stored in 'Marketers table'.
From a good design perspective, you should keep these tables as separate.
for your current requirements,
if you do not need data from Marketers so often, why do you need to include that in Stores. you would just end up fetching extra data each time.
say if tomorrow if some new info and the mapping changes to one to many or vice versa, your current design will work perfectly fine.
and of course from future maintainence view, it is easier to update current design.
although, i would also, suggest you to add an independent primary to Stores table also.
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I'm currently trying to build a football database in MySQL. It should store the fixtures from different leagues, plus their results, odds and some other information.
Is the scheme I just created correct or are there any mistakes in it? If so, what can I improve? I'm also not really sure about the link between tblMatch and tblTeams.
Afterwards I want to be able to make a Query where I can select a fixture including the points the home and away team got before the match, plus the average amount of goals of the teams. Like the new fields: 'homeTeamPoints', 'awayTeamPoints' ect.
So my question is: Where should I put these fields? In an extra table or should I put those in the table: 'tblMatch' and store the precalculated values there?
I hope you get what I tried to explain.
Best Regards
-bababow
A few notes:
You will want to replace "homeTeam" and "awayTeam" with "homeTeamID" and "awayTeamId" which will be foreign keys to the tblTeams table. This will enforce that the teams in the match both actually exist.
Remove the matchID and competitionID from the teams. I'm assuming teams can participate in many matches and competitions and therefore this structure will not support that.
What do you want to know about competitions? Is this a tournament? You may want to have a "bracket" and/or "tournament winner" column in there to store the results of the overall tournament.
Those are my main thoughts, other than that it looks OK.
In my perspective if the values of both the fields needs update regularly and table tblMatch data size is large then you should take it into separate table. if both the fields are updates whenever whole record is change then it could be in tblMatch table.
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If we ask the following question of an individual: "Does that person have children?" There are three possible answers: "Yes", "No", "Unknown". With a table design that stores the person as a record in a people table, and a child as a record in a children table with a foreign key to the people table, we cannot distinguish between "No" and "Unknown". Both answers imply no rows in the children table.
What is the best way to store the answer to that question that can distinguish between the three states? My current thought is storing that information as a separate field on the people table, but that opens up data integrity issues.