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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 ...
2025年3月7日签到记录贴 - 签到区 - 清泛IT社区，为创新赋能！
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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...
2025年1月15日签到记录贴 - 签到区 - 清泛IT社区，为创新赋能！
...动生成的,如果您还未签到,请点此进行签到的操作. 我在 2025-01-15 09:01 完成签到,是今天第一个签到的用户,获得随机奖励 小红花 10,另外我还额外获得了 小红花 10.我今天最想说:「该会员没有填写今日想说内容.」. 我在 2025-01-15 09:1...