从mysql中的不同表中获取2个主键

Question

I'm doing my final year project and planning to do comment feature on my system. The customer that have purchased the meal only can comment or give feedback about that particular meal. So, I need to get the Meal_ID and Cust_ID from table 1 and table 2 in order to keep track who's comment on what meal. I just want to ask is it possible to select multiple primary keys from different tables in one sql query? Thanks in advance!

I have 3 table as shown below.

Answer 1

Foreign Key:

Example:

CREATE TABLE Orders
(
O_Id int NOT NULL,
OrderNo int NOT NULL,
P_Id int,
PRIMARY KEY (O_Id),
FOREIGN KEY (P_Id) REFERENCES Persons(P_Id)
)

Description: The following SQL creates a FOREIGN KEY on the "P_Id" column when the "Orders" table is created:

Fetching Data:

Ya it it possible to select two Primary keys from a single select statement with the help of JOIN Query so that you can combine both the tables and you can get the result with the help of single query.

There are different types of Join available and you can use any such method:

1. JOIN
2. Left JOIN
3. Right JOIN