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问题:
I want to store an array in a record.
Table1:
ID, Name, Friends (friends should be an array) 1, Bill, 2&3 2, Charles, 1&3 3, Clare, 1
I want to be able to do a search like this:
SELECT * FROM Table1 WHERE Friends='3'
to find everyone who has Clare listed as a friend
回答1:
Unless you have a really good reason for doing this, you should keep your data normalized and store the relationships in a different table. I think perhaps what you are looking for is this:
CREATE TABLE people ( id int not null auto_increment, name varchar(250) not null, primary key(id) ); CREATE TABLE friendships ( id int not null auto_increment, user_id int not null, friend_id int not null, primary key(id) ); INSERT INTO people (name) VALUES ('Bill'),('Charles'),('Clare'); INSERT INTO friendships (user_id, friend_id) VALUES (1,3), (2,3); SELECT * FROM people p INNER JOIN friendships f ON f.user_id = p.id WHERE f.friend_id = 3;
+----+---------+----+---------+-----------+ | id | name | id | user_id | friend_id | +----+---------+----+---------+-----------+ | 1 | Bill | 1 | 1 | 3 | | 2 | Charles | 2 | 2 | 3 | +----+---------+----+---------+-----------+ 2 rows in set (0.00 sec)
回答2:
This looks like the perfect place for a relation table instead: Table 1:
ID, Name 1, Bill 2, Charles 3, Clare
Table 2 (the relation table)
ID, FriendID 1, 2 1, 3 2, 1 2, 3 3, 1
The second table keeps track of the friend relations by connecting ID's from Table1.
回答3:
You might want a comma-separated value, but it's not recommended. Why not use another table for showing relationships?
Table2 ---------------------- PARENT_ID | FRIEND_ID ---------------------- 1 | 2 1 | 3 2 | 1 2 | 3 ----------------------