One-to-many Query in MySQL - mysql

Question

What's the best way to query one-to-many in MySQL? This is a simplified version of the database I am working on (if anything doesn't look right tell me):
CREATE TABLE Tenant(
tenant_id int NOT NULL,
first_name varchar(20),
last_name varchar(20),
PRIMARY KEY (tenant_id)
);
CREATE TABLE Rent(
tenant_id int NOT NULL,
month enum('JAN', 'FEB', ...),
date_paid date NOT NULL,
amount_paid int NOT NULL,
FOREIGN KEY (tenant_id) REFERENCES Tenant(tenant_id)
);
(The reason that there is month and date_paid in the Rent table is because the tenant does not necessarily pay the rent all at once). What I want the tenant's name to appear once which would just be a Left Join, but I want all the amount paid in a particular month listed as columns for each tenant, I am not sure how to go about that. I am not really sure how to do that since your are dealing with an unknown amount of columns, haven't touched that yet in MySQL. Or is there a better strategy? Also, how would I go about creating my own variable like MONTH-YEAR (I don't think that exists as a native variable in MySQL). Thank you!
Edit:
Just to simplify it further I am using this format:
create table rent(
tenant_id int not null,
year year,
amount_paid int,
foreign key (tenant_id) references tenant(tenant_id)
);
If I understand what duffymo said below I should use group by (I know I am misunderstanding somewhere because it only shows the first example for each year):
SELECT Tenant.first_name, Rent.year, Rent.amount_paid
FROM Tenant
LEFT JOIN Rent
ON Tenant.tenant_id = Rent.tenant_id
GROUP BY year;
This is what I want the query to look like, the number under each year is the amount paid (I actually just realized it's a little bit more complex than what I how explained):
first_name 2009 2008 2007
John 500 500 NULL
Ann 1000 NULL NULL
Bob NULL 700 700

Answer 1

If you have MONTH and YEAR columns, you can do a GROUP BY to select amount paid broken out as you'd wish. If you have a PAID_DATE column, one way to do this would be to have a BEFORE INSERT trigger that runs when the PAID_DATE is set. That way users don't have to enter values, and data integrity can be guaranteed.