SQL Server After Update Trigger - Single Table - 2 Columns - sql

Question

I have a table (dbo.membersdatatable) that has multiple columns. I would like this trigger to update a column called "memberstatus" when "memberdesignation" is updated to a value of "10" from a value of "9".
-------SQL STATEMENT BELOW---------------
IF UPDATE([MemberDesignation])
--need to make it so it will recognize when memberdesignation = 10
UPDATE dbo.MembersDataTable
SET MemStatus = '0'
FROM dbo.MembersDataTable AS mdtbl
INNER JOIN inserted AS i ON i.StudentID = mdtbl.StudentID

Answer 1

Use triggers SPARINGLY. For example, my system has 138 tables, 550 stored procedures and only 28 triggers. I wish I had less.
But if you decide a trigger is required, it will look something like this:
CREATE TRIGGER [t_MemberDesignationSideEffect] ON [dbo].MembersDataTable
FOR UPDATE
AS
SET NOCOUNT ON
IF NOT ( UPDATE([MemberDesignation]) ) RETURN
-- REMINDER: All triggers can and will fire for a set of rows...not just one
UPDATE mdtbl
SET MemStatus = '0'
FROM inserted i
JOIN dbo.MembersDataTable mdtbl on i.StudentID = mdtbl.StudentID
JOIN deleted d on d.StudentID = mdtbl.StudentID
WHERE i.memberdesignation = '10'
and d.memberdesignation = '9'
GO

Answer 2

You are writing an update trigger on table. Here you can use deleted and inserted magic tables. In case of update trigger:
Deleted table contains the row as it was before the UPDATE statement.
Inserted table contains the row as it is after the UPDATE statement.
create trigger update_member_status
on membersdatatable
for update
as
begin
declare #old_designation int
declare #new_designation int
set #old_designation = (select memberdesignation from deleted)
set #new_designation = (select memberdesignation from inserted)
if (#old_designation = 9 and #new_designation = 10)
begin
update membersdatatable
set memstatus = '0'
from membersdatatable as mdtbl
inner join inserted as i on i.StudentID = mdtbl.StudentID
end
end

Answer 3

You are going to update member status of all rows with a
memberdesignation = 10
you can probably add conditions to this query in order to update only the ones you want by using a date field or another
Simply call this procedure after updating your table
CREATE PROCEDURE USP_MemberStatusRules()
AS
UPDATE dbo.MembersDataTable
SET MemStatus = '0'
WHERE memberdesignation = 10
AND .....
AND .....
GO