Failed Constraint - 如何在sqlite3表中正確插入某些內容？

Question

我們被要求創建一個數據庫，然後創建一個表格，然後填充它。 這裏是我想出迄今：

sqlite3 me5.db; 

create table petID(pet_id int(3) PRIMARY KEY, pet_name varchar(10), pet_type varchar(10), pet_age int(3)); 

INSERT INTO petID(pet_id, pet_name, pet_type, pet_age) VALUES(246, 'ROVER', 'DOG', 12); 
INSERT INTO petID(pet_id, pet_name, pet_type, pet_age) VALUES(298, 'SPOT', 'DOG', 2); 
INSERT INTO petID(pet_id, pet_name, pet_type, pet_age) VALUES(341, 'MORRIS', 'CAT', 4); 
INSERT INTO petID(pet_id, pet_name, pet_type, pet_age) VALUES(519, 'TWEEDY', 'BIRD', 2); 

create table petowner(pet_id int(3), owner varchar(100) PRIMARY KEY, FOREIGN KEY(pet_id) REFERENCES petID(pet_id) ON DELETE CASCADE); 

INSERT INTO petowner(pet_id, owner) VALUES(246, 'SAM COOK'); 
INSERT INTO petowner(pet_id, owner) VALUES(298, 'TERRY KIM'); 

然而，當我插入下面這兩個：

INSERT INTO petowner(pet_id, owner) VALUES(341, 'SAM COOK'); 
INSERT INTO petowner(pet_id, owner) VALUES(519, 'TERRY KIM'); 

我得到一個「約束失敗」的錯誤。任何想法如何解決這一問題？謝謝

Answer 1

您違反的約束是petowner的主鍵;它可以防止'SAM COOK'出現兩次。

如果寵物可以有多個業主，那麼petowner表的主鍵必須包含兩列：

CREATE TABLE petowner(
    pet_id int(3), 
    owner varchar(100), 
    PRIMARY KEY(pet_id, owner), 
    FOREIGN KEY(pet_id) REFERENCES petID(pet_id) ON DELETE CASCADE 
);