小编And*_*y M的帖子

我想从多个具有多个外键的表中选择sqlite中的结果,我试过JOIN但是效果不好; 例如 :

一张桌子STUDENT:

 CREATE TABLE STUDENT (
 STUDENT_NAME    TEXT        NOT NULL,
 STUDENT_NUMBER  INTEGER  PRIMARY KEY  NOT NULL,
 STUDENT_ADDRESS TEXT        NOT NULL
 );

和一张桌子EXAMS:

 CREATE TABLE EXAMS(
 EXAM_CODE      INTEGER   PRIMARY KEY  NOT NULL,
 EXAM_SUBJECT   TEXT        NOT NULL,
 EXAM_LOCATION  TEXT        NOT NULL
 );

还有一张表格WROTE_EXAM,用于为编写特定考试的学生提供信息

 CREATE TABLE WROTE_EXAM (
 STUDENT_NUMBER  INTEGER     NOT NULL,
 EXAM_CODE       INTEGER     NOT NULL,
 DATE            DATE        NOT NULL,
 FOREIGN KEY(STUDENT_NUMBER) REFERENCES STUDENT(STUDENT_NUMBER),
 FOREIGN KEY(EXAM_CODE) REFERENCES EXAMS(EXAM_CODE));

这是插入表格的示例数据:

STUDENT_NAME : John
STUDENT_NUMBER: …