mysql - 使用 EXIST 命令创建 sql View 语句

Question

我必须在sql中编写一条使用exist命令的create view语句。我尝试在网上查找，但遇到了一些困难。我尽力编写创建 View 文件，但它现在不起作用。我知道我需要在语句中使用关键字 EXIST。我试图创建的语句是

Write a query that shows returns the name and city of the university that has no people in database
that are associated with it.

到目前为止我写的代码是这样的

CREATE VIEW exist AS
SELECT a.university_name, a.city
FROM lab5.university as a
INNER JOIN lab5.person as b
ON a.uid = b.uid
WHERE b.uid  NOT EXIST

我正在使用的表是

         Table "table.university"
     Column      |         Type          |                        Modifiers     
-----------------+-----------------------+--------------------------------------
 uid             | integer               | not null default nextval('university_uid_seq'::regclass)
 university_name | character varying(50) | 
 city            | character varying(50) |

并且

            Table "table.person"
 Column |         Type          |                      Modifiers                       
--------+-----------------------+-----------------------------------------------
 pid    | integer               | not null default nextval('person_pid_seq'::reg class)
 uid    | integer               | 
 fname  | character varying(25) | not null
 lname  | character varying(25) | not null

Answer 1

您好，请使用以下代码并让我知道反馈

CREATE VIEW checkuni AS SELECT a.university_name, a.city FROM university as a WHERE NOT EXISTS (SELECT p.uid FROM person as p WHERE p.uid = a.uid)