Question

我在SQL Server数据库中有4个表，其中包含以下模式：

考勤

CREATE TABLE [dbo].[Attendance] (
[AttendanceId] UNIQUEIDENTIFIER DEFAULT (newid()) NOT NULL,
[CourseId]     UNIQUEIDENTIFIER NOT NULL,
[StudentId]    UNIQUEIDENTIFIER NOT NULL,
[SubjectId]    UNIQUEIDENTIFIER NOT NULL,
[Semester]     INT              NOT NULL,
[Month]        NVARCHAR (50)    NOT NULL,
[Count]        INT              NOT NULL,
CONSTRAINT [PK_Attendance] PRIMARY KEY NONCLUSTERED ([AttendanceId] ASC),
CONSTRAINT [FK_Attendance_Student] FOREIGN KEY ([StudentId]) REFERENCES [dbo].[Student] ([StudentId]) );

课程

CREATE TABLE [dbo].[Course] (
[CourseId] UNIQUEIDENTIFIER DEFAULT (newid()) NOT NULL,
[Name]     NVARCHAR (50)    NOT NULL,
CONSTRAINT [PK_Course] PRIMARY KEY NONCLUSTERED ([CourseId] ASC)
);

学生

CREATE TABLE [dbo].[Student] (
[StudentId] UNIQUEIDENTIFIER DEFAULT (newid()) NOT NULL,
[CourseId]  UNIQUEIDENTIFIER NOT NULL,
[Name]      NVARCHAR (100)   NOT NULL,
[RollNo]    INT              NOT NULL,
[Semester]  INT              NOT NULL,
CONSTRAINT [PK_Student] PRIMARY KEY NONCLUSTERED ([StudentId] ASC),
CONSTRAINT [FK_Student_Course] FOREIGN KEY ([CourseId]) REFERENCES [dbo].[Course] ([CourseId])
);

主题

CREATE TABLE [dbo].[Subject] (
[SubjectId] UNIQUEIDENTIFIER DEFAULT (newid()) NOT NULL,
[CourseId]  UNIQUEIDENTIFIER NOT NULL,
[Name]      NVARCHAR (100)   NOT NULL,
[Semester]  INT              NOT NULL,
CONSTRAINT [PK_Subject] PRIMARY KEY NONCLUSTERED ([SubjectId] ASC),
CONSTRAINT [FK_Subject_Course] FOREIGN KEY ([CourseId]) REFERENCES [dbo].[Course] ([CourseId])
);

我需要按以下格式创建出勤报告：

课程名称 | 学生姓名 | 主题名称 | 学期 | 月 | 计数

请告诉我我需要使用哪种SQL查询，如果需要对架构进行任何更改，请提出相同的建议。

我期待着您的回复。

谢谢，

Answer 1

您需要在查询中使用JOIN，以便它只返回与出勤表中的[StudentId]匹配的行。

e.g。

SELECT c.CourseName, s.StudentName, u.SubjectName, u.Semester, a.Month, a.Count
FROM Student s 
    JOIN Attendance a ON s.StudentId = a.StudentId
    JOIN Course c ON a.CourseId = c.CourseId
    JOIN Subject u ON c.CourseId = u.CourseId

沿着这些行的某些内容只会返回与

特别匹配的行

从不同表中检索数据（SQL Server）

1 个答案: