Hi I have data that I need to store in my database. My website is about tv-shows, and the data I'm talking about is basically seasons and episodes. My concern is about whether I should use two tables or one. I'll make myself more clear:
Option 1:
seasons_table
post_id
season_number
season_title
language
subtitles
item_date (when it was created)
item_modified (when it was last modified)
episodes_table
post_id
season_id
episode_number
episode_title
item_date
item_modified
Option 2:
unique table
post_id
item_type (season or episode)
season_number
season_title
language
subtitles
season_id
episode_number
episode_title
item_date
item_modified
I can already see for myself that with Option 1 there's gonna be a lot of common fields between the two tables, while with Option 2 there's gonna be a lot of fields that are never gonna be used (e.g. an episode will never have a value in the field season_title since it just needs a value for season_id to be linked to that season).
So which one is the best option? I'm willing to choose option 2, but I'm worried that those empty fields are gonna waste memory or loading time or whatever while processing any data in that table. Is that true? Thanks in advance to everyone, I hope I made myself clear.
By the way my website is wordpress based and I'm gonna use a custom table, but I think i'm gonna use some wordpress functions to process data like $wpdb->insert and so on...
Two tables is the best approach here, that more closely adheres to the rules of database normalization. If there's concern about duplication you need to better evaluate where you're storing data.
item_date and item_modified are probably unique for each entry even if they are "duplicated" in terms of schema. Don't worry about this.
Whatever post_id is, you'll have to evaluate if you have a direct relationship between post and these two tables, or from post to seasons to episodes.
Related
I am using WordPress with some custom post types (just to give a description of my DB structure - its WP's).
Each post has custom meta, which is stored in a separate table (postmeta table). In my case, I am storing city and state.
I've added some actions to WP's save_post/trash_post hooks so that the city and state are also stored in a separate table (cities) like so:
ID postID city state
auto int varchar varchar
I did this because I assumed that this table would be faster than querying the rather large postmeta table for a list of available cities and states.
My logic also forced me to add/update cities and states for every post, even though this will cause duplicates (in the city/state fields). This must be so because I must keep track of which states/cities exist (actually have a post associated with them). When a post is added or deleted, it takes its record to or from the cities table with it.
This brings me to my question(s).
Does this logic make sense or do I suck at DB design?
If it does make sense, my real question is this: **would it be faster to use MySQL's "SELECT DISTINCT" or just "SELECT *" and then use PHP's array_unique on the results?**
Edits for comments/answers thus far:
The structure of the table is exactly how I typed it out above. There is an index on ID, but the point of this table isn't to retrieve an indexed list, but to retrieve ALL results (that are unique) for a list of ALL available city/state combos.
I think I may go with (I don't know why I didn't think of this before) just adding a serialized list of city/state combos in ONE record in the wp_options table. Then I can just get that record, and filter out the unique records I need.
Can I get some feedback on this? I would imagine that retrieving and filtering a serialized array would be faster than storing the data in a separate table for retrieval.
To answer your question about using SELECT distinct vs. array_unique, I would say that I would almost always prefer to limit the result set in the database assuming of course that you have an appropriate index on the field for which you are trying to get distinct values. This saves you time in transmitting extra data from DB to application and for the application reading that data into memory where you can work with it.
As far as your separate table design, it is hard to speculate whether this is a good approach or not, this would largely depend on how you are actually preforming your query (i.e. are you doing two separate queries - one for post info and one for city/state info or querying across a join?).
The is really only one definitive way to determine what is fastest approach. That is to test both ways in your environment.
1) Fully normalized table(when it have only integer values and other tables have only one int+varchar) have advantage when you not dooing full table joins often and dooing alot of search on normalized fields. As downside it require large join/sort buffers and result more complex queries=much less chance query will be auto-optimized by mysql. So you have optimize your queries yourself.
2)Select distinct will be faster in almost any cases. Only case when it will be slower - you have low size sort buffer in /etc/my.conf and much more size memory buffer for php.
Distinct select can use indexes, while your code can't.
Also sending large amount of data to your app require alot of mysql cpu time and real time.
I have been looking for some optimization tips since I´m doing a RPG modification which uses MySQL to store data by PHP.
I´m using one unique table to store all user information in columns by his unique ID, and I have to store (many?) data for each user. Weapons and other information.
I´m using explode and implode as a method to store the weapons, for example, in one column with the 'text' value. I don´t know if that´s a good practice and I don´t know if I will have performance problems if I get thousands of players doing tons of UPDATES , SELECT , etc, requests.
I read that a Junction table may be better to store the weapons and all those information, but I don´t know if that will get better information that you request it by the explode method.
I mean, I should store all the weapons in a different table, each weapon with his information (each weapon have some information, like different columns, I use multiple explode for that inside the main explode) and the user owner of that weapon to identify the weapon than just have them in one column.
It can be 100 items at least to store, I don´t know if it´s good to make 100 records per user on a different table and call all of them all the time better than just call the column and use explode.
Also I want to improve my skills and knowledge to make the best performance MySQL database I can.
I hope somebody can tell me something.
Thanks, and sorry for my stupid english grammar.
It is almost always best practice to normalize your table data. There are some exceptions to this rule (especially in very high volume databases), but you probably do not need to worry about those exceptions until you get to the point of first understanding how to properly normalize and index your tables.
Typically, try to arrange your tables in a way that mimics real-world objects and their relations to each other.
So, in your case you have users - that is one table. Each user might have multiple weapons. So, you now have a weapons table. Since multiple different users might have the same weapon and each user might have multiple weapons, you have a many-to-many relationship between them, so you should have a table "users_weapons" or similar that does nothing but relate user id's to weapon id's.
Now say the users can all have armor. So now you add an armor table and a users_armor table (as this is likely many-to-many as well).
Just think through the different aspects of your game and try to understand the relationships between them. Make sure you can model these relationships in database tables before you even bother writing any code to actually implement the functionality.
Yes it is better to use several tables instead of one. It's better to db performance, easier to understand, easier to maintain and simplier to use as well.
Let's suggest that one user has several weapons with multiple features(but not unique among all weapons). And in one place in your game you just need to know the value of one specific feature:
doing it by your way you'll need to find user row in users table, fetch on column, explode it several times, and there you have your value, but it complicates even more if you want to change it and save then.
better way is having one table for user details(login, password, email etc), another table which keeps user weapons(name of weapon, image maybe) and table in which will be all features, special powers of weapons kept. You could keep all possible features of all weapons in extra table as well. This way you if you already know user id from user table, you'll have to only join 2 tables in your sql query, and there you got value of feature of specific weapon of user.
Example pseudo schema of tables:
users
user_id
user_name
password
email
weapons
weapon_id
user_id
weapon_name
image
weapons_features
feature_id
weapon_id
feature_name
feature_value
And if you really want to use some ordered data in text field in database encode it to JSON or serialize it. This way you don't have to explode and implode it!
As all guys said, typically you should start from normalized database structure.
If performance is ok, then great, nothing to do.
If not, you can try many different things:
Find and optimize query which works slow.
Denormalize queries - sometimes joins kill performance.
Change data access pattern used in application.
Store data in file system or use NoSQL/polyglot persistence solution.
I have a questionnaire for users to be matched by similar interests: 40 categories, each with 3 to 10 subcategories. Each of the subcategories has a 0 - 5 value related to how interested they are in that subcategory (0 being not even remotely interested, 5 being a die-hard fan). Let's take an example for a category, sports:
<input type="radio" name="int_sports_football" value="0">0</input>
<input type="radio" name="int_sports_football" value="1">1</input>
<input type="radio" name="int_sports_football" value="2">2</input>
<input type="radio" name="int_sports_football" value="3">3</input>
<input type="radio" name="int_sports_football" value="4">4</input>
<input type="radio" name="int_sports_football" value="5">5</input>
With so many of these, I have a table with the interest categories, but due to the size, have been using CSV format for the subcategory values (Bad practice for numerous reasons, I know).
Right now, I don't have the resources to create an entire database devoted to interests, and having 40 tables of data in the profiles database is messy. I've been pulling the CSV out (Which looks like 0,2,4,1,5,1), exploding them, and using the numbers as I desire, which seems really inefficient.
If it were simply yes/no I could see doing bit masking (which I do in another spot – maybe there's a way to make this work with 6-ary values? ). Is there another way to store this sort of categorized data efficiently?
You do not do this by adding an extra field per question to the user table, but rather you create a table of answers where each answer record stores a unique identifier for the user record. You can then query the two tables together using joins in order to isolate only those answers for a specific user. In addition, you want to create a questions table so you can link the answer to a specific question.
table 1) user: (uniqueID, identifying info)
table 2) answers: (uniqueID, userID, questionID, text) links to unique userID and unique questionID
table 3) question: (uniqueID, subcategoryID, text) links to uniqueID of a subcategory (e.g. football)
table 4) subcategories: (uniqueID, maincategoyID, text) links to uniqueID of a mainCategory (e.g sports)
table 5) maincategories: (uniqueID,text)
An individual user has one user record, but MANY answer records. As the user answers a question, a new record is created in the answers table, storing the uniqueID of the user, the uniqueID of the question, and the value of their answer.
An answer record is linked to a single user record (by referencing the user's uniqueID field) and a single question record (via uniqueID of question).
A question record is linked to a single subcategory record.
A subcategory record is linked to a single category record.
Note this scheme only handles two levels of categories: sports->football. If you have 3 levels, then add another level in the same manner. If your levels are arbitrary, there may be some other scheme more suited.
okay, so, given that you have 40 categories and let's assume 10 subcategories, that leaves us with 400 question-answer pairs per user.
now, in order to design the best intermediary data storage, I would suggest starting out with a few questions:
1) what type of analysis will I need
2) what resources do I have
3) is this one time solution or should it be reused in future
Well, if I were you, I would stick to very simple database structure e.g.:
question_id | user_id | answer
if I would foresee more this kind of polls going on with same questions and probably having same respondents, I would further extend the structure with "campaign_id". This would work as raw data storage which would allow quick and easy statistics of any kind.
now, you said database is no option. well, you can mimic this very same structure using arrays and create your own statistical interface that would work based on the array storage type, BUT, you would save their and your time if you could get sql. as others suggest, there is always sqlite (file based database engine), which, is easy to use and setup.
now, if all that does not make you happy, then there is another interesting approach. if data set is fixed, meaning, that there are pretty much no conditional questions, then, given that you could create question index, you could further create funny 400byte answer chunk, where each byte would represent answer in any of the given values. then what you do is you create your statistical methods that, based on the question id, can easily operate with $answer[$user][$nth] byte (or $answer[$nth][$user] -- again, based on the type of statistics you need)
this should help you get your mind set on the goal you want to achieve.
I know you said you don't have the resources to create a database, but I disagree. Using SQL seems like your best bet and PHP includes SQLite (http://us2.php.net/manual/en/book.sqlite.php) which means you wouldn't need to set up a MySQL database if that were a problem.
There are also tools for both MySQL and SQLite which would allow you to create tables and import your data from the CSV files without any effort.
maybe I am confused but it seems like you need a well designed relational database.
for example:
tblCategories (pkCategoryID, fldCategoryName)
tblSubCategory (pkSubCategoryID, fkdSubCategoryName)
tblCategorySubCategory(fkCategoryID,fkSubCategoryID)
then use inner joins to populate the pages. hopefully this helps you :)
i consider NoSQL architecture as a solution to scaling MySQL field in agile solutions.
To get it done asap, I'd create a class for "interest" category that constructs sub-categories instance which extends from category parent class, carrying properties of answers, which would be stored as a JSON object in that field, example:
{
"music": { // category
"instruments": { // sub category
"guitar": 5, //intrest answers
"piano": 2,
"violin": 0,
"drums": 4
},
"fav artist":{
"lady gaga": 1,
"kate perry": 2,
"Joe satriani": 5
}
}
"sports": {
"fav sport":{
"soccer": 5,
"hockey": 2,
}
"fav player":{
"messi": 5,
"Jordan": 5,
}
}
}
NOTE that you need to use "abstraction" for the "category" class to keep the object architecture right
I have many fields which are multi valued and not sure how to store them? if i do 3NF then there are many tables. For example: Nationality.
A person can have single or dual nationality. if dual this means it is a 1 to many. So i create a user table and a user_nationality table. (there is already a nationality lookup table). or i could put both nationalities into the same row like "American, German" then unserialize it on run-time. But then i dont know if i can search this? like if i search for only German people will it show up?
This is an example, i have over 30 fields which are multi-valued, so i assume i will not be creating 61 tables for this? 1 user table, 30 lookup tables to hold each multi-valued item's lookups and 30 tables to hold the user_ values for the multi valued items?
You must also keep in mind that some multi-valued fields group together like "colleges i have studied at" it has a group of fields such as college name, degree type, time line, etc. And a user can have 1 to many of these. So i assume i can create a separate table for this like user_education with these fields, but lets assume one of these fields is also fixed list multi-valued like college campuses i visited then we will end up in a never ending chain of FK tables which isn't a good design for social networks as the goal is it put as much data into as fewer tables as possible for performance.
If you need to keep using SQL, you will need to create these tables. you will need to decide on how far you are willing to go, and impose limitations on the system (such as only being able to specify one campus).
As far as nationality goes, if you will only require two nationalities (worst-case scenario), you could consider a second nationality field (Nationality and Nationality2) to account for this. Of course this only applies to fields with a small maximum number of different values.
If your user table has a lot of related attributes, then one possibility is to create one attributes table with rows like (user_id, attribute_name, attribute_value). You can store all your attributes to one table. You can use this table to fetch attributes for given users, also search by attribute names and values.
The simple solution is to stop using a SQL table. This what NoSQL is deigned for. Check out CouchDB or Mongo. There each value can be stored as a full structure - so this whole problem could be reduced to a single (not-really-)table.
The downside of pretty much any SQL based solution is that it will be slow. Either slow when fetching a single user - a massive JOIN statement won't execute quickly or slow when searching (if you decide to store these values as serialized).
You might also want to look at ORM which will map your objects to a database automatically.
http://en.wikipedia.org/wiki/List_of_object-relational_mapping_software#PHP
This is an example, i have over 30
fields which are multi-valued, so i
assume i will not be creating 61
tables for this?
You're right that 61 is the maximum number of tables, but in reality it'll likely be less, take your own example:
"colleges i have studied at"
"college campuses i visited"
In this case you'll probably only have one "collage" table, so there would be four tables in this layout, not five.
I'd say don't be afraid of using lots of tables if the data set you're modelling is large - just make sure you keep an up to date ERD so you don't get lost! Also, don't get caught up too much in the "link table" paradigm - "link tables" can be "entities" in their own rights, for example you could think of the "colleges i have studied at" link table as an "collage enrolments" table instead, give it it's own primary key, and store each of the times you pay your course fees as rows in a (linked) "collage enrolment payments" table.
I am trying to discover the best way to design my database to organize information related to events.
I have an events table which contains all the information about the event such as, a unique id, title of the event, venue etc.
Now each event can have multiple ticket types and the number and type of tickets will change with each event.
Is it better to have a events_tickets table which has a seperate row for each ticket type e.g.
event_id ticket_type price
1 standard 20
1 deluxe 40
1 cheap 10
Or is it better to have the table formatted so that the information is on one row?
event_id ticket_information
1 standard:20,deluxe:40,cheap:10
If I use the first way I could end up with 10 rows per event which when multiplied by lots of events could become very large, whereas the second version could have problems with data integrity.
the first one... definitely. :) having as much of your data as separate as possible is ALWAYS the best way... it makes it much more usable and much easier to change/upgrade/expand the code later.
In fact I would have 3 tables: events, event_options and ticket_types
event_options would just be literally a link table between the events and the ticket_types, and can include other information you need to hold per event. This way it will make it easier still to a) search by ticket type and b) add more ticket types because when you come to add a new ticket type to an existing event (or something similar) you will have a lot more issues the second way.
The official answer is to do it the first way. If you only ever have exactly the same three types of tickets, then you can get on with having three "ticket price" fields. But otherwise, relational-purism tells you to go with the first.
I'm assuming that in any event you have an "events" table. Tell you what: search for "third normal form" on your favorite search engine, and you'll learn a lot about designing databases.
The first way is better. It is more normalised. Why does this matter? It means it's much easier to query your data. You don't want to use the second way, because it'll be really complicated and time-consuming to retrieve data at a later time.