Question

I have two tables connected with one to many relationship.
Parent Table is a simple user table with id and first_name column

Parent

id | first_name     
1  | Bob  
2  | Dick  
3  | Harry  
4  | Tom  
5  | Holly  

Child Table contains insurance selection for a user.

Child

id | insu_id      | user_id   | year  
1  | 188765       | 1         | 2008  
2  | 188765       | 1         | 2009  
3  | 188765       | 1         | 2010   
4  | 188765       | 1         | 2011  
5  | 188765       | 1         | 2012  

I want to copy insurance selection of user_id 1 to all rest of the users i.e. 2, 3, 4, 5 in child table so that the table should look like

id | insu_id      | user_id   | year  
1  | 188765       | 1         | 2008   
2  | 188765       | 1         | 2009      
3  | 188765       | 1         | 2010  
4  | 188765       | 1         | 2011  
5  | 188765       | 1         | 2012  
6  | 188765       | 2         | 2008  
7  | 188765       | 2         | 2009   
8  | 188765       | 2         | 2010  
9  | 188765       | 2         | 2011   
10 | 188765       | 2         | 2012  
11 | 188765       | 3         | 2008  
12 | 188765       | 3         | 2009   
13 | 188765       | 3         | 2010  
14 | 188765       | 3         | 2011  
15 | 188765       | 3         | 2012  
16 | 188765       | 4         | 2008  
17 | 188765       | 4         | 2009   
18 | 188765       | 4         | 2010  
19 | 188765       | 4         | 2011  
20 | 188765       | 4         | 2012  
21 | 188765       | 5         | 2008  
22 | 188765       | 5         | 2009   
23 | 188765       | 5         | 2010  
24 | 188765       | 5         | 2011  
25 | 188765       | 5         | 2012  

What Can I do

INSERT INTO child(insurance_id, user_id, year) SELECT insurance_id, '2', year FROM child WHERE user_id = 1

INSERT INTO child(insurance_id, user_id, year) SELECT insurance_id, '3', year FROM child WHERE user_id = 1

INSERT INTO child(insurance_id, user_id, year) SELECT insurance_id, '4', year FROM child WHERE user_id = 1

INSERT INTO child(insurance_id, user_id, year) SELECT insurance_id, '5', year FROM child WHERE user_id = 1

What I want

I don’t want to run 4 different INSERT INTO() SELECT queries because number of users can increase beyond that. I want one query selecting user_id dynamically rather than hard coding.

Answer 1

I have tried that and it seems to work. I get the insurance data from child table for the first user and join it with all other users in the parent table in order to insert the result. You may have to fix the column names if they are not the same as your database.

INSERT INTO child(insurance_id, user_id, year)
SELECT a.insurance_id, b.id, a.year
FROM
child a, parent b
WHERE a.user_id = 1 AND b.id > 1
ORDER BY b.id, a.year

This will always insert insurance data for all users except the one with id = 1. No matter how many of them you have. Hope that helps 🙂