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How to implement a unique index on two columns in rails
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add_index :subscriptions, [:user_id, :content_id], unique: true
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Rails has_and_belongs_to_many migration
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You need to add a separate join table with only a restaurant_id and user_id (no primary key), in alphabetical order.
First run your migrations, then edit the generated migration file.
Rails 3
rails g migration create_restaurants_users_table
Rails 4:
rails g migration create_restaurants...
How to change the foreign key referential action? (behavior)
...e refers to Users table:
mysql> SHOW CREATE TABLE UserDetails;
:
:
`User_id` int(11) DEFAULT NULL,
PRIMARY KEY (`Detail_id`),
KEY `FK_User_id` (`User_id`),
CONSTRAINT `FK_User_id` FOREIGN KEY (`User_id`) REFERENCES `Users` (`User_id`)
:
:
First step:
mysql> ALTER TABLE `UserDeta...
Importing data from a JSON file into R
...tes" "startPrice" "lastVote.timestamp" "lastVote.user.name" "lastVote.user.user_id"
> winners[,c("winner","startPrice","lastVote.user.name")]
winner startPrice lastVote.user.name
1 68694999 0 Lamur
> winners[,c("votes")]
[[1]]
ts user.name ...
Can you do greater than comparison on a date in a Rails 3 search?
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Note.
where(:user_id => current_user.id, :notetype => p[:note_type]).
where("date > ?", p[:date]).
order('date ASC, created_at ASC')
or you can also convert everything into the SQL notation
Note.
where("user_id = ? AND n...
What is a proper naming convention for MySQL FKs?
...d table name]_[referencing field name]
Example:
CREATE TABLE users(
user_id int,
name varchar(100)
);
CREATE TABLE messages(
message_id int,
user_id int
);
ALTER TABLE messages ADD CONSTRAINT fk_messages_users_user_id
FOREIGN KEY (user_id) REFERENCES users(user_...
Insert auto increment primary key to existing table
...mposite primary key using the following code:
DROP TABLE IF EXISTS SAKAI_USER_ID_MAP;
CREATE TABLE SAKAI_USER_ID_MAP (
USER_ID VARCHAR (99) NOT NULL,
EID VARCHAR (255) NOT NULL,
PRIMARY KEY (USER_ID)
);
INSERT INTO SAKAI_USER_ID_MAP VALUES ('admin...
When should I use a composite index?
...To create a friends' tables (i.e. for a social network) we need 2 columns: user_id, friend_id.
Table Strcture
user_id (medium_int)
friend_id (medium_int)
Primary Key -> (user_id, friend_id)
By virtue, a Primary Key (PK) is unique and by creating a composite PK, Innodb will automatically chec...
Setting Environment Variables for Node to retrieve
...les (in this case) are being used to pass credentials to your application. USER_ID and USER_KEY can both be accessed from process.env.USER_ID and process.env.USER_KEY respectively. You don't need to edit them, just access their contents.
It looks like they are simply giving you the choice between l...
MySQL Insert into multiple tables? (Database normalization?)
...00.com');
full script:
drop table if exists users;
create table users
(
user_id int unsigned not null auto_increment primary key,
username varchar(32) unique not null
)
engine=innodb;
drop table if exists user_profile;
create table user_profile
(
profile_id int unsigned not null auto_increment p...