I've tried putting the COMMIT TRAN in a if else loop, and I'm still getting this error.
I have to enroll a student in a class. If the number of seats after enrollment falls in negative, I have to reverse it and print a message saying can't enroll. I have put other error messages just to see how transactions work.
CREATE PROCEDURE dbo.EnrollStudent ( @CourseID AS INTEGER,
@StudentID AS VARCHAR(20) ) AS
BEGIN
DECLARE @StatusID INTEGER
DECLARE @Status VARCHAR(50)
DECLARE @CurrentSeats INTEGER
DECLARE @ErrorCode INTEGER
SET @StatusID=0
IF EXISTS (SELECT 1
FROM dbo.CourseEnrollment
WHERE dbo.CourseEnrollment.CourseId=@CourseID AND dbo.CourseEnrollment.StudentId=@StudentID )
BEGIN
BEGIN TRAN Tr1
SET @StatusID = 1
SELECT @ErrorCode=@@ERROR
IF (@ErrorCode<>0) GOTO OTHERPROBLEM
ELSE
COMMIT TRAN Tr1
END
IF EXISTS ( SELECT 1
FROM dbo.CourseEnrollment
FULL OUTER JOIN dbo.Courses
ON dbo.Courses.CourseId=@CourseID
WHERE dbo.CourseEnrollment.StudentId<>@StudentID AND dbo.Courses.Faculty IS NULL )
BEGIN
BEGIN TRAN Tr2
SET @StatusID=2
SELECT @ErrorCode=@@ERROR
IF (@ErrorCode<>0) GOTO OTHERPROBLEM2
ELSE
COMMIT TRAN Tr2
END
IF @StatusID=0
BEGIN
IF EXISTS ( SELECT 1
FROM dbo.Courses
WHERE dbo.Courses.CourseId=@CourseID AND dbo.Courses.Faculty IS NOT NULL )
BEGIN
BEGIN TRAN Tr3
SET @StatusID=3
BEGIN TRAN InsertingValues
INSERT INTO dbo.CourseEnrollment (dbo.CourseEnrollment.StudentId,dbo.CourseEnrollment.CourseId)
VALUES (@StudentID,@CourseID);
SELECT @ErrorCode=@@ERROR
IF (@ErrorCode<>0) GOTO InsertProblem
ELSE
COMMIT TRAN InsertingValues
BEGIN TRAN UpdateCourses
UPDATE dbo.Courses
SET OpenSeats = OpenSeats-1
WHERE dbo.Courses.CourseId = @CourseID
SELECT @ErrorCode=@@ERROR
IF (@ErrorCode<>0) GOTO UpdateProblem
ELSE
COMMIT TRAN UpdateCourses
SELECT @CurrentSeats=OpenSeats
FROM dbo.Courses
WHERE dbo.Courses.CourseId = @CourseID
IF (@CurrentSeats<0) GOTO PROBLEM
ELSE
COMMIT TRAN Tr3
END
END
OTHERPROBLEM:
BEGIN
PRINT 'Unable to set status'
ROLLBACK TRAN
END
OTHERPROBLEM2:
BEGIN
PRINT 'Unable to set status'
ROLLBACK TRAN
END
UpdateProblem:
BEGIN
PRINT 'Not able to update values'
ROLLBACK TRAN InsertingValues
END
InsertProblem:
BEGIN
PRINT 'Not able to insert'
ROLLBACK TRAN InsertingValues
END
PROBLEM:
BEGIN
PRINT 'Seats Full!'
ROLLBACK TRAN
END
IF @StatusID = 1
BEGIN
SET @Status = 'The Student is already enrolled'
END;
ELSE IF @StatusID = 2
BEGIN
SET @Status = 'Cannot enroll until faculty is selected'
END
ELSE IF @StatusID = 3
BEGIN
SET @Status = 'Student Enrolled'
END
SELECT @Status
END;
This correctly updated the tables, but is giving the following errors:
(1 row(s) affected)
(1 row(s) affected)
Unable to set status
Msg 3903, Level 16, State 1, Procedure EnrollStudent, Line 101
The ROLLBACK TRANSACTION request has no corresponding BEGIN TRANSACTION.
Unable to set status
Msg 3903, Level 16, State 1, Procedure EnrollStudent, Line 108
The ROLLBACK TRANSACTION request has no corresponding BEGIN TRANSACTION.
Not able to update values
Msg 3903, Level 16, State 1, Procedure EnrollStudent, Line 115
The ROLLBACK TRANSACTION request has no corresponding BEGIN TRANSACTION.
Not able to insert
Msg 3903, Level 16, State 1, Procedure EnrollStudent, Line 123
The ROLLBACK TRANSACTION request has no corresponding BEGIN TRANSACTION.
Seats Full!
Msg 3903, Level 16, State 1, Procedure EnrollStudent, Line 131
The ROLLBACK TRANSACTION request has no corresponding BEGIN TRANSACTION.
(1 row(s) affected)
FULL OUTER JOIN
) isn't telling you useful information. I'm at least not able to understand what you expect it to tell you, or why that would be relevant. Also, unless you wrap the entire thing in a single serialized transaction, you can't trust your results; it's possible to add too many students, get negative seats, simply not report (future) negative seats... This isn't actually safe for a concurrent system. Personally, I'd probably start byINSERT
ing into a table with a high-resolution timestamp, with no transaction. – Responser