SQL更新查詢填充從第一行只有第一個值

Question

我有三個不同的表：人，person_pet和PET

create table person ( 
    id integer primary key, 
    name text 
); 

create table person_pet (
    person_id integer, 
    pet_id integer primary key 
); 

create table pet (
    id integer primary key, 
    breed text, 
    owner integer 
); 

在那之後，我插入一些值：

insert into person (id, name) 
    values (0, "Name1"), (1, "Name2"), (2, "Name3"); 

insert into person_pet (person_id, pet_id) 
    values (0,1), (1,0), (2,3), (1,2); 

insert into pet (id, breed, owner) 
    values (0, "PetA", null), (1, "PetB", null), (2, "PetC", null), (3, "PetD", null); 

我想將表pet中owner列的數據更新爲person_pet表中顯示的所有者的實際id。也就是說，我希望得到以下結果：

PET表

id breed owner 
0  PetA  1 
1  PetB  0 
2  PetC  1 
3  PetD  2 

我試圖用一個選擇的子查詢這個SQL查詢：

update pet set owner = (
    select person.id 
    from person, person_pet, pet 
    where person.id = person_pet.person_id and 
    person_pet.pet_id = pet.id 
); 

這產生這個輸出（在只有ID填充一個所有者）：

PET表

id breed owner 
0  PetA  1 
1  PetB  1 
2  PetC  1 
3  PetD  1 

如果我運行它自己的子查詢，

select person.id 
    from person, person_pet, pet 
    where person.id = person_pet.person_id and 
    person_pet.pet_id = pet.id; 

，我希望出現的結果：

PET表

id breed owner 
0  PetA  1 
1  PetB  0 
2  PetC  1 
3  PetD  2 

但我不使用時，設法讓這更新命令。

Answer 1

我做這個測試的SQL Server解決方案， 可以幫助你：

update pet set owner = person.id 
from pet inner join person_pet on pet.id = person_pet.pet_id 
inner join person on person.id = person_pet.person_id 

與此輸出：

id breed owner 
0 PetA 1 
1 PetB 0 
2 PetC 1 
3 PetD 2 

Answer 2

SQLite的，請嘗試以下格式：

UPDATE pet 
SET owner = (
     SELECT PER.id 
     FROM person PER 
     INNER JOIN person_pet PPE ON PPE.person_id = PER.id 
     INNER JOIN pet PET ON PET.id = PPE.pet_id) 
WHERE id IN (SELECT id FROM pet);