Insert statement conflicted with foreign key - sql

Question

I'm new to SQL and I'm trying to insert values into my table. I'm currently using SQL Server Management Studio.
CREATE TABLE Materials
(
materials_ID int NOT NULL PRIMARY KEY,
floor_boards int NOT NULL,
power_Points int NOT NULL,
electrical_Wiring int NOT NULL,
stairs_Pack int NOT NULL,
);
SELECT * FROM materials;
-- Creation of the JobCards Table
CREATE TABLE jobCards
(
customer_id VARCHAR(50)
FOREIGN KEY REFERENCES Customers(customer_id),
jobCardID int NOT NULL PRIMARY KEY,
materials_ID int
FOREIGN KEY REFERENCES Materials(materials_ID),
jobType VARCHAR(150) NOT NULL,
rate decimal NOT NULL,
no_of_days int NOT NULL,
city VARCHAR(150) NOT NULL,
);
-- Selectin statement output values in Jobcards
SELECT * FROM jobCards;
-- Insert statement allows data to be inputed to table
INSERT INTO jobCards (customer_id, jobCardID, materials_ID, jobType, rate, no_of_days, city)
VALUES
('0001', 11000, 1, 'Full Conversion', 120000, 7, 'Pretoria'),
('0002', 10478, 2, 'Semi Conversion', 1080, 2, 'Pretoria'),
('0003', 14253, 3, 'Floor Boarding', 900, 2, 'Pretoria'),
('0004', 11258, 4, 'Full Conversion', 120000, 8, 'Pretoria'),
('0005', 12058, 5, 'Semi Conversion', 1080, 3, 'Pretoria'),
('0006', 13697, 6, 'Full Conversion', 120000, 7, 'Pretoria'),
('0007', 10211, 7, 'Full Conversion', 120000, 7, 'Pretoria'),
('0008', 10471, 8, 'Semi Conversion', 1080, 2, 'Pretoria'),
('0009', 13521, 9, 'Semi Conversion', 1080, 3, 'Pretoria'),
('0010', 10102, 10, 'Floor Boarding', 900, 2, 'Pretoria');
I have inserted the tables that have the issue. Whenever I run my program I get this error
The INSERT statement conflicted with the FOREIGN KEY constraint
"FK__jobCards__materi__2F10007B". The conflict occurred in database
"DomingoRoofWorks", table "dbo.Materials", column 'materials_ID'.

Answer 1

Remember that a foreign key is a field that help us to link two tables together. We can use a foreign key to refer to the primary key in another table.
You can try to insert some rows in the Materials table before inserting into the jobCards table.
Here is an example:
-- After creating the tables:
INSERT INTO Materials (materials_ID, floor_boards, power_Points, electrical_Wiring, stairs_Pack)
VALUES (1, --someIntValue, --someIntValue, --someIntValue, --someIntValue)
After inserting all the rows needed you can use those Ids as a foreign key in the jobCards table. At this point, this query could be performed wothout problem.
INSERT INTO jobCards (customer_id, jobCardID, materials_ID, jobType, rate, no_of_days, city)
VALUES
('0001', 11000, 1, 'Full Conversion', 120000, 7, 'Pretoria'),
('0002', 10478, 2, 'Semi Conversion', 1080, 2, 'Pretoria'),
('0003', 14253, 3, 'Floor Boarding', 900, 2, 'Pretoria'),
('0004', 11258, 4, 'Full Conversion', 120000, 8, 'Pretoria'),
('0005', 12058, 5, 'Semi Conversion', 1080, 3, 'Pretoria'),
('0006', 13697, 6, 'Full Conversion', 120000, 7, 'Pretoria'),
('0007', 10211, 7, 'Full Conversion', 120000, 7, 'Pretoria'),
('0008', 10471, 8, 'Semi Conversion', 1080, 2, 'Pretoria'),
('0009', 13521, 9, 'Semi Conversion', 1080, 3, 'Pretoria'),
('0010', 10102, 10, 'Floor Boarding', 900, 2, 'Pretoria');