Retrieve Data from Different Tables (SQL Server) - sql

Question

I have 4 tables in a SQL Server database with following schema:
Attendance
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]) );
Course
CREATE TABLE [dbo].[Course] (
[CourseId] UNIQUEIDENTIFIER DEFAULT (newid()) NOT NULL,
[Name] NVARCHAR (50) NOT NULL,
CONSTRAINT [PK_Course] PRIMARY KEY NONCLUSTERED ([CourseId] ASC)
);
Student
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])
);
Subject
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])
);
I need to create a attendance report in the following format:
Course Name | Student Name | Subject Name | Semester | Month | Count
Please tell me what SQL Query I need to use and if there's any change in schema required then suggest the same.
I'm looking forward to have your replies.
Thanks,

Answer 1

You need to use a JOIN in your query so that it only returns rows which match a [StudentId] from the Attendance table.
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
Something along these lines will only return rows which specifically match