https://medium.com/wesionary-team/integrating-migration-tool-in-gin-framework-golang-139676bc4af7
Arquivo da tag: Migration
How to rollback a specific migration?
Using Rails, how can I set my primary key to not be an integer-typed column?
[code type=ruby]
create_table :employees, {:primary_key => :emp_id} do |t|
t.string :emp_id
t.string :first_name
t.string :last_name
end
Is there documentation for the Rails column types?
- String:
- Limited to 255 characters (depending on DBMS)
- Use for short text fields (names, emails, etc)
- Text:
- Unlimited length (depending on DBMS)
- Use for comments, blog posts, etc. General rule of thumb: if it’s captured via textarea, use Text. For input using textfields, use string.
- Integer:
- Whole numbers
- Float:
- Decimal numbers stored with floating point precision
- Precision is fixed, which can be problematic for some calculations; generally no good for math operations due to inaccurate rounding.
- Decimal:
- Decimal numbers stored with precision that varies according to what is needed by your calculations; use these for math that needs to be accurate
- See this post for examples and an in-depth explanation on the differences between floats and decimals.
- Boolean:
- Use to store true/false attributes (i.e. things that only have two states, like on/off)
- Binary:
- Use to store images, movies, and other files in their original, raw format in chunks of data called blobs
- :primary_key
- This datatype is a placeholder that Rails translates into whatever primary key datatype your database of choice requires (i.e. serial primary key in postgreSQL). Its use is somewhat complicated and not recommended.
- Use model and migration constraints (like validates_uniqueness_of and add_index with the :unique => true option) instead to simulate primary key functionality on one of your own fields.
- Date:
- Stores only a date (year, month, day)
- Time:
- Stores only a time (hours, minutes, seconds)
- DateTime:
- Stores both date and time
- Timestamp
- Stores both date and time
- Note: For the purposes of Rails, both Timestamp and DateTime mean the same thing (use either type to store both date and time). For the TL;DR description of why both exist, read the bottom paragraph.