子查询语句中缺少表达式？

Question

我正在使用臭名昭著的“CityJail”模式来回答“列出所有犯罪次数超过平均水平且未被列为暴力罪犯的罪犯的姓名”的问题。

这是我的代码：

SELECT first, last 
FROM criminals NATURAL JOIN
crimes
GROUP BY first, last
HAVING COUNT(*) > (SELECT AVG(COUNT(DISTINCT crime_id))
FROM crimes)
AND (SELECT v_status = 'N' FROM crimes)
GROUP BY first, last
);

但是我得到一个错误：

ORA-00936: missing expression 00936. 00000 - "missing expression" *Cause:
*Action: Error at Line: 7 Column: 22

当我将代码更改为：

SELECT first, last 
FROM criminals NATURAL JOIN
crimes
GROUP BY first, last
HAVING COUNT(*) > (SELECT AVG(COUNT(DISTINCT crime_id))
FROM crimes)
AND v_status = 'N'
GROUP BY first, last
);

我得到一个错误：

ORA-01787: only one clause allowed per query block 01787. 00000 - "only one clause allowed per query block" *Cause:
*Action: Error at Line: 8 Column: 1

我做错了什么？

罪犯：

Name        Null?    Type         
----------- -------- ------------ 
CRIMINAL_ID NOT NULL NUMBER(6)    
LAST                 VARCHAR2(15) 
FIRST                VARCHAR2(10) 
STREET               VARCHAR2(30) 
CITY                 VARCHAR2(20) 
STATE                CHAR(2)      
ZIP                  CHAR(5)      
PHONE                CHAR(10)     
V_STATUS             CHAR(1)      
P_STATUS             CHAR(1)

罪行：

Name            Null?    Type      
--------------- -------- --------- 
CRIME_ID        NOT NULL NUMBER(9) 
CRIMINAL_ID     NOT NULL NUMBER(6) 
CLASSIFICATION           CHAR(1)   
DATE_CHARGED             DATE      
STATUS                   CHAR(2)   
HEARING_DATE             DATE      
APPEAL_CUT_DATE          DATE      
DATE_RECORDED            DATE

Answer 1

修复 Having 子句中的标量子查询

  SELECT first
      , last
   FROM criminals cls
NATURAL
   JOIN crimes 
  WHERE v_status = 'N'
  GROUP BY first
      , last
 HAVING COUNT(1) >(
         SELECT AVG(COUNT(DISTINCT crime_id))
   FROM crimes
   GROUP BY criminal_id);

标量查询在您的两次尝试中都是错误的。

我将条件 WHERE v_status = 'N' 移到了主查询中（您只关心 non-violent 的罪犯）。

子查询语句中缺少表达式？

Missing expression inside sub-query statement?

sql

oracle

subquery