I am new to SQL, I am trying to "map" data from several tables in ONE database to create ONE table with relational information. For example, I am trying to take data from my tables ps3_productcategories, ps3_categories and "map"/"merge" to the ps3_products table, The previous tables contains all the "category information" needed to map to "correct products".
I am trying to "MAP" the productID to the "correct"=> categoryID=> categoryName=> categoryParent etc.....
Any help would be appreciated
I suggest you look into views, it may be what you are looking for, although they do not create this in another database they do allow to create virtual tables from existing data.
A database View is known as a "virtual table" which allows you to query the data in it.
See the MySql manpage on views..
And here is a small tutorial on the subject.
If you really need this in a seperate database, you can easily create a view and export the results of that, and import it in other database.
Related
Good example will be shopify. Where you have N number of users (in this case each user assume site). And each user will have it's own records in DB. But db schema will be the same (same tables for each user, products, customers, orders etc.).
So question is what will be the best way to organize this kind of solution?
Store everything in one DB but in a different tables, or run separate DB for each user (but then will be question with maintaining, scalability and automatization)
possible solution:
We can use one DB with common tables like products, customers, orders etc. And we will have table users where we store records about each site.
In tables products, customers we will group all records by user_id.
This is one of possible solutions. But if we will have 1000 users (sites), each will have ~2k products, and ~100k customers, we can end up with tables which has millions of records, so questions will be:
how it will perform compare to each user (site) would have it's own DB?
how reliable this approach? bigger data, harder maintain, backup/restore
safety, if something wrong with one source thousands will be affected
Any links etc. will be much appreciated, thanks!
Create a mysql user for each tenant
Add a tenant_id column to each table
Add a view for each table that filters based on tenant_id = mysql_user
Use a trigger to automatically populate the tenant_id column on INSERT
Restrict the tenant mysql users to only access the views, not the raw tables
I wrote up a blog post on how I was able to convert a large single-tenant mysql application to a multi-tenant application in a weekend using this technique.
https://opensource.io/it/mysql-multi-tenant/
I recommend reviewing databases by well-supported open source solutions. With this in mind, here's a pretty simple schema I found real quick that'd explain a good working solution for this with scale-ability in mind.
http://www.zentut.com/sql-tutorial/sql-sample-database/
I have this file Generate_multiTanentMysql.php i do all steps with PHP script
https://github.com/ziedtuihri/SaaS_Application
Solution Design Pattern :
Creating a database user for each tenant
Renaming every table to a different and unique name (e.g. using a prefix ‘someprefix_’)
Adding a text column called ‘id_tenant’ to every table to store the name of the tenant the row belongs to
Creating a trigger for each table to automatically store the current database username to the id_tenant column before inserting a new row
Creating a view for each table with the original table name with all the columns except id_tenant. The view will only return rows where (id_tenant = current_database_username)
Only grant permission to the views (not tables) to each tenant’s database user Then, the only part of the application that needs to change is the database connection logic. When someone connects to the SaaS, the application would need to:
Connect to the database as that tenant-specific username
As a general question which would really help me "connect the dots" with my studies.
I am currently doing exercises working with DAO and Learning how to add tables automatically. Although i have been working with databases for many years, i question, what type of scenerarios would it be vantagious to use this function. When is it necessary to add tables to a database in an automatic way? Up until now, in all my experiences the tables i need have Always been defined from the beginning and I cant think of a situation where I could of benefited from using this function. For example, i use frequently delete queries to help me clear tables and re-populate them, but when would it be necessary to actually "create" a new table"?
Yes, I have seen a scenario where new tables were created 'on the fly' (either via SQL create, or just DAO). With a shared database on a server, the application called for importing Excel data that a particular user was responsible for, so a table was created on the fly. Multiple users, changes in staff, need to keep data independent, etc. we could create their own table (name based on userid) that they had interfaces to do whatever they wanted with their own data. Not a typical scenario, but worked well for this application.
I have a bit of a complex issue to deal with here at the moment and would love some help please.
I have exported data from SugarCRM in CSV format to be imported in to my new app. Now my app works slightly differently in terms of database schema. I use auto-incrementing integers for id's where as SugarCRM uses long alphanumeric strings like dc4c072c-ec0e-26b6-8780-4a9e7ec8375d.
I need to be able to take the data for say accounts and contacts, using the SugarCRM pivot table export from accounts_contacts, and change the id's, while keeping them all linked correctly. I then need to use the changed data to import in to my database, where each record in the contacts table contains an account_id field which links them to accounts, rather than a pivot table.
Now, my first thoughts would be to import all the required data in to clean database and use a lookup table with four fields in it to change the id's. So I would have old_account_id, new_account_id, old_contact_id, new_contact_id. I'd then use that table to find the right id's and amend the data.
The only issue I have with this, is that my SQL isn't amazing, so I'm having difficulty visualising and writing the query to use the lookup table and change the data. So I would love some help with this.
Also, once I have the query and the correct amended data, I need another query to then create the contacts table using an account_id field from the pivot table.
Hope you guys can help out. Thanks in advance.
Are you planning on keeping the data in sync? I'd suggest adding a "sugar_id" column in your app and a "your_app_id" column in SugarCRM. This way the native id column remains the same and that it will maintain a reference to the record in the other system.
I have this assignment that I think someone should be able to help me. I have 5 ACCESS databases wvrapnaoh.accdb, wvrappaul.accdb, ....etc. These databases have about 45 tables each and 15 forms. The good part is the structure, the name and the fields of each table in all the databases are all the same except the data or the records are different. For example I have a stress table in wvrapnoah as well as wvrappaul with the same fields in both tables but different data or records.
So, I need to merge all these five into a new Access database that will have the same structure as the 5 databases but will include the complete data that is all the records from the 5 databases merged into this new database.The same applies to even the 15 forms. It does not seem to be having a primary key I guess. I was planning to add a field for each table that would give me the name of the database as well from which it was merged. Example I will add a DBName field in Wvrapnoah in all the tables and add the name Noah in that field for all the records in each table. I basically need to automate this code.
I need a script (VBA or anything) so that the guys creating these databases can just run this script the next time and merge the databases.
Talking about the 'table' part of the problem:
Questions
Are the databases / table names defined or you don't know them?
Are you able to use linked tables?
I believe the straightforward way to merge all of them is to link all tables into a single access DB and then run a UNION ALL query. It would be something like this:
SELECT "HANK", *
FROM MyTableHank
UNION ALL
SELECT "JOHN", *
FROM MyTableJohn;
Notice I defined a field to identify the origin of the data being merged ("HANK", "JOHN"), as you suggested above.
About the forms, I believe you'll need to import them and then review the whole code. It basically depends on what the forms are doing. If they're query-based won't be a big deal (importing / fixing the queries, will make the form works). However, if the forms are related to the tables, you'll have more work to do.
I need to create an ERD for our DB system. As it happens, there are lots and lots of tables, and no one really understands much of it. What's more, the same DB has tables for different applications, so not all tables are relevant to my application. I need an ERD for only my application's tables.
I tried creating ERD from MySQL workbench. It allows me to select a subset of the tables to put on an ERD, but that's the problem: I don't know which tables to select ( One of the reasons to build the diagram in the first place :-) ).
What I do know are some of the 'main' tables involved. What I'm looking for is this: I tell the tool some 5-10 of these main tables I'm interested in, and the tool automatically picks up all the tables that are linked to these tables, and creates the ERD for them.
Any pointers?
Otherwise, I'll have to live with building my list of tables manaully, one by one...
http://www.fabforce.net/ has a nice tool called DBDesigner, I have used this in the past for some reverse engineering on a datamodel.