SQL查詢...我需要從表1的同一列中插入2個值到表2的2個不同列中

Question

insert into friends (user_id1,user_id2) select user_id from user where UserName='summer'or UserName='winter'這將導致錯誤。 我想將'summer'的user_id插入到user_id1中，並將'winter'的user_id插入到user_id2中。 請幫忙？

Answer 1

insert into friends (user_id1,user_id2) 
select user_id, -1 from user where UserName='summer'

update friends 
set user_id2 = (select user_id from user where UserName='winter')
where user_id2 = -1

Answer 2

Select必須具有與插入相同的列數，因此：

INSERT INTO friends (user_id1,user_id2)
SELECT (SELECT user_id FROM user where UserName='Summer') AS user_id1, (SELECT user_id FROM user WHERE UserName='Winter') AS user_id2

應該做的把戲

Answer 3

INSERT INTO table2 (user_id1,user_id2)
SELECT
  (SELECT UserName
   FROM table1
   WHERE UserName='Summer') AS user_id1,

  (SELECT UserName
   FROM table1
   WHERE UserName='Winter') AS user_id2

SQL字段