sqlplus子查询的使用

我有3张表格，必须找出每个申请者的申请人数、姓名和职位总数

CREATE TABLE    APP (
appNum      varchar2(10)    not null,
appName     varchar2(70),
constraint applicant_Pkey primary key (appNum)
);

CREATE TABLE    POS (
posNum          varchar2(10)    not null,
posStartOfferDt     date        not null,
constraint pos_Pkey primary key (posNum, posStartOfferDt)
);



CREATE TABLE    APPLICATION (
appcnPosNum     varchar2(10)    not null,
appcnPosStOffrDt    date        not null,
appcnAppNum     varchar2(10)    not null,
appcnDt         date,
constraint application_Pkey primary key (appcnPosNum, appcnPosStOffrDt, appcnAppNum),
constraint application_Fkey1 foreign key (appcnPosNum, appcnPosStOffrDt) references     POSITION(posNum, posStartOfferDt),
constraint application_Fkey2 foreign key (appcnAppNum) references APPLICANT(appNum)
);

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我尝试过使用子查询、自然连接，但都不适合我。

您使用的是哪个sql版本？mySql、MSSQL/T-SQL、Oracle等？从应用程序a中选择a.appNum、a.appName、COUNT（ap.appcnAppNum）通过a.appNum、a.appName在a.appNum=ap.appcnAppNum组上左加入应用程序ap

SELECT   appNum, appName, COUNT(*)
FROM     applicant
JOIN     application ON applicant.appNum = application.appcnAppNum
GROUP BY appNum, appName