I've created a db in mySQL that stores many things, but specially images. The table name for storing the images is image, like so:
image (image_id, title, caption, filename, published_date, ...)
It's been almost 2 years and i've uploaded almost 5000 images into the table.
Now, i want to add a new functionality. I want to group similar images so when im looking at an image, i can also have the option to look at images that are similar.
I'm not sure if i need a new table or should i use the same table or both. Any ideas/suggestions on how it should be?
You should create another table with that similiarities.
Why can't it be the same table ? One record in You table can have many similiar records (so it will be adding many columns to that table or for every similiarity there will be another row in YOur table. So the only logical option is to create another table.
IdFromMainTable | IdOfSimiliarRecord
Later on You can show that similiarites in a view easily joining that table by IdFromMainTable. Or both IdOfSimiliarRecord and IdFromMainTable. [depends if u want to add 2 records for similiar records or just one for similiar pair]
It sounds like what you want to do is create tags for the images. There are a number of ways to do that, but adding the tags to the same table would prevent a whole lot of joins from taking place and would likely be faster. You could just store the tags as JSON (if you're using MySQL =>7.5.8).
Related
I'm having conception difficulties to implement something in a database. I have two solutions for a problem, and I was wondering which one is the best.
Problem :
Let's picture a table speciality with 2 fields : speciality_id and speciality_name.
So for example :
1 - Mage
2 - Warrior
3 - Priest
Now, I have a table user with fields such as user_id, name, firstname etc ...
In this table, there is a field called speciality. The speciality stores an integer, corresponding to the speciality_id of the table speciality.
That would be acceptable for users that have only one speciality. I want to improve the model to be able to have multiple specialities for a user.
Here are my two solutions :
Create a table 'solution1' which link the user_id with the speciality_id and remove the speciality field in the user table. So for a user which has 2 specialities, 2 rows will be created in the table 'solution1'.
Change the type of the field speciality in the user table to be able to write down the specialities, separated with commas.
For example 2;3
The problem I got with the second solution is for making foreign keys between my table user and my table specialities, to link them. I may have a bit more difficulties with the PHP in the future too, while wanting to get the specilities for a user (will need to use a parser I guess).
Which solution do you find is the best ?
Thanks.
Absolutely go with your first solution.
Create a third "Many-to-Many" table that allows you to relate a user to multiple specialties. This is the only way to go in your case.
When designing tables, you always want to have each column contain one and only one data element. Think about what querying your second solution would look like. What would you do when you wanted to see all users who had a given specialty?
You might try something like this:
select * from user where specialty like '%2%'
Well, what happens when you have specialties that go to 12? Now "2" matches multiple entities. You could devolve further and try to be tricky, but...you really should just make your data design as normal as possible to avoid all the mess, headache, and errors. Go with Solution 1.
i think the best way is to follow solution1 cause solution2 will end up will lot of complexity later on
I have a database like this:
Database example
My problem is I need multiple entries in the Substrate spot.
Kind of like a 3 dimensional database. I need to add in things like, hay, straw, potato peels etc. But it needs to be on the same spot like a list just for substrates. I cant go down the rows because that would be messing with the wrong mushroom and the only alternative I can think about is making substrate01, substrate02 substrate03 ... but since this can vary a lot, it makes no sense to make hundreds of rows just to reserve enough space for entries. One might only have 1 substrate and another might have 50 I need it to be dynamic.
Create another table, which contains a column for the key of the one row your trying to add to, and another column for the name, like substrate1, substrate2
So table one row might look like:
MushroomKey, mushroomname
Table two might look like:
Substratekey, mushroomkey, substratename
You might also want to learn about the normal forms of a database
If I'm understanding correctly, the general method to do this is to have a second table, linked by ID that contains one substrate. Then have one record per substrate in the second table.
If you need to display it all on one line, you can join the tables and use 'group concat' to assemble them.
I'm working on a project to make a digital form of this paper
this paper (can't post image)
and the data will displayed on a Web in a simple table view. There will be NO altering, deleting, updating. It's just displaying (via SELECT * of course) the data inputted.
The data will be inserted via android app and stored in a single table which has 30 columns in mysql.
and the question is, is it a good idea if i use a single table? because i think there will be no complex operation in the sql.
and the other question is, am i violating some rules for this method?
I need your opinion. thanks.
It's totally ok to use only one table, if that suits your needs. What you can do to make the database a little bit 'smarter' is add new tables for attributes in your paper that will be repeated. So, for example, the Soil Type could be another table where there are two columns, ID and Description, and you will use it as a foreign key in each record in the main table. You need this if you want your database to be in 3NF.
To sum up, yes you can have one table if that's all you need. However, adding more tables might help save some space and make your database more flexible. It's up to you to decide! :)
My Question, is actually a question about the usability / performance of a concept / idea I had:
The Setup:
Troughout my Database, two (actually three) fields always re-appear constantly: title and description (and created). The title is always a VARCHAR(100) and the description always a TEXT.
Now, to simplify those tables, I thought about something (and changed it in that way): Wouldnt it be more useful to just create a table named content, with id, title, description and created as only fields, and always point to that table from all others?
Example:
table tab has id, key and content_id (instead of title, description and created)
table chapter has id, story_id and content_id (" ")
etc
The Question:
Everything works fine so far, but my only fear is performance. Will I run into a bottleneck, doing it this way, or should I be fine? I have about 23 different tables pointing to content right now, and some of them will hold user-defined content (journals, comments, etc) - so the number of entries in content could get quite high.
Is this setup better, or equal to having title and description in every separate table?
Edit: And if it turns out to be a bad idea, what are alternatives to mantain/copying certain fields like title and description into ~25 tables?
Thanks in advance for the help!
There is no clear answer for your question because it mainly depends on usage of the tables, so just consider following points:
How often will you need write to the tables? In case of many inserts/updates having data in one big table can cause problems because all write operations will target the same table.
How often do you need data stored in table with common data? If title or description are not needed most of the time for your select this can be OK. If you need title every time then take into account that you wile always have to JOIN table with common data.
How do you manage your database schema? It can be easier to write some simple tool for creation/checking table structure. In MySQL you can easily access data dictionary with DESCRIBE table_name or through INFORMATION_SCHEMA database.
I'm working on project with 700+ tables where some of the fields have to be present in every table (when was record created, timestamp of last modification). We have simple script that helps with this, because having all data in one table would be disastrous.
Apologize for the long topic, I didn't intend for it to be this long, but it's a pretty simple issue I've been having. :)
Let's say you have a simple table called tags that has columns tag_id and tag. The tag_id is simply an auto increment column and the tag is the title of the tag. If I need to add a description field, that would be around 1-2 paragraphs on average (max around 3-4 paragraphs probably), should I simply add a description field to the table or should I create a new table called tag_descriptions and store the descriptions with the tag_id?
I remember reading that it is better to do this because if you do a query that doesn't select the description, that description field will still slow down mysql. Is this true? I don't even remember where I read that from, but I've been kind of following it for a couple years now... Finally I question if I need to do this, I have a feeling I don't. You'd also need to inner join whenever you need the description field.
Another question I have is, is it generally bad to create new tables that will only hold very few rows at the max? What if this data doesn't fit anywhere else?
I have a simple case below which relates to these two questions.
I have three tables content, tags, and content_tags that make up a many to many relationship:
content
content_id
region (enum column with
about 6-7 different values and most
likely won't grow later on)
tags
tag_id
tag
content_tags
content_id
tag_id
I want to store a description around 1-2 paragraphs for each tag, but also for each region. I'm wondering what would be the best way to do this?
Option A:
Just add a description column to the
tags table
Create a new table for
region_descriptions
Option B:
Create a new table called
descriptions with fields: id,
description, and type
The id would be id of the content or
id of the enum field
The type would be whether it is a tag
description, or region description
(Would use the enum column for this)
Maybe have a primary key on the id and type?
Option C:
Create a new table for tag_descriptions
Create a new table for region_descriptions
Option A seems to be a good choice if adding the description column doesn't slow down mysql select queries that don't need the description.
Assuming the description column would slow down mysql, option B might be a good choice. It also removes the need for a small table with just 6-7 rows that would hold the region descriptions. Although now that I think of it, would it be slow to connect to this table if originally to get a region description you'd only need to go through very little rows.
Option C would be ideal if the description columns would slow down mysql and if a small table like region descriptions would not matter.
Maybe none of these options are the best, feel free to offer another option. Thanks.
P.S. What would be an ideal column type to use to hold data that usually 1-2 paragraphs, but might be a little more sometimes?
I don't think it really matters if you don't handle thousands of queries per minute. If you are going to have a zillion queries per minute, then I would implement the various options and perform benchmarks for all these options. Based on the results, you can make a decision.
In my (admittedly somewhat uninformed) opinion, it really depends on how much you'll be using both of them.
If properly indexed, that JOIN should not be very expensive. Also, a larger table will be slower. It inhibits caching, and takes longer to access stuff, although indexing seriously mitigates this problem.
If you'll be joining tag names to tag IDs a LOT, and only rarely will be using the descriptions, I'd say go with separate tables. If you'll be using the descriptions more often, go with one table.
For the first part of your question: if you have a tag with an id, a name and a description, you should save it in 1 table.
Now, this query
SELECT name FROM tags WHERE id = 1;
will NOT slow down if you have 1, 2 or 20 extra fields in there.