Question

我在使用MySQL并且无法计算总数。我正在尝试找出一个SQL查询，它将使用以下数据和查询返回正确的结果。我想得到总案件的数量。在我的查询结果中，F和I计数是正确的M案例计数关闭。如果案件有一个F那么它应该算作F案件而不是我的查询正在进行的M案件。

数据：

BKNUM      CG             Charge Description            Severity
123456      1       POSS CONT SUB W/I MAN/DEL/SELL          F
123456      1       POSS LEGEND DRUG W/O PRESCRIPTION       M
654321      1       VIOLATION OF PROBATION     M            I
987654      1       AGGRAVATED ASSAULT                      F
987654      1       POSS OF HANDGUN WHILE INTOXICATED       M
987654      1       POSSESSION OF PROHIBITED WEAPON         M
876543      1       VIOLATION OF PROBATION     M            I
765432      1       CRIM ATT-BURGLARY BUILDING              F
765432      1       POSSESSION OF BURGLARY TOOLS            M
234567      1       POSS MARIJUANA W/I MAN/DEL/SELL         F
234567      1       DRIVING WHILE LICENSE S/R/C             M
234567      1       IMPROPER DISPLAY OF REGISTRATION        M
345678      1       DRIVING WHILE LICENSE S/R/C             M
345678      1       EVADING ARREST                          M
345678      1       RESISTING OFFICIAL DETENTION            M
345678      1       UNLAWFUL POSS WEAPON                    M
345678      1       POSS OF CONT SUBSTANCE                  M
345678      1       CRIM ATT-POSS OF CONT SUB-MARIJUANA     M

查询：

Select Severity as 'Charge CLass',
Count(Distinct BKNUM, CG) as 'Total Cases',
Count(BKNUM) as 'Toatl Charges'
From test
group by severity

结果我得到：

Charge Class        Total Cases     Total Charges
    F                     4             4
    I                     2             2
    M                     5            12

结果应该是：

Charge Class        Total Cases     Total Charges
    F                     4             4
    I                     2             2
    M                     1             12

非常感谢任何帮助。

Answer 1

您需要在BKNUM上使用GROUP BY，在CG列上使用DISTINCT。请参阅Distinct on multiple columns in MySQL以供参考 - 它应该引导您找到您正在寻找的解决方案。

Answer 2

SELECT CASE WHEN S = 1 THEN 'I' WHEN S = 2 THEN 'M' ELSE 'F' END
,    Qty
,    BKNUM
,    CG
FROM (
SELECT MAX(CASE WHEN Severity = 'I' THEN 1 WHEN Severity = 'M' THEN 2 ELSE 3 END) AS S
,    COUNT(*) AS Qty
,    BKNUM
,    CG
FROM Test
GROUP BY BKNUM, CG ) AS t

Answer 3

不是最漂亮的查询，但我认为它应该有效：

select t.severity, count(distinct bknum) "Total Cases", a.c "Total Charges" 
from test t 
join (select severity, count(*) c from test group by severity) a on t.severity = a.severity
where t.severity in ('i','f') 
   or (t.severity = 'm' and bknum not in (select bknum from test where severity = 'f'))
group by t.severity, a.c

或许这个：

select t.severity, count(distinct bknum, cg) "Total Cases", a.c "Total Charges" 
from test t 
join (select severity, count(*) c from test group by severity) a on t.severity = a.severity
where t.severity in ('i','f') 
   or (t.severity = 'm' and (bknum, cg) not in (select bknum, cg from test where severity = 'f'))
group by t.severity, a.c

MySQL选择Count Distinct

3 个答案: