Solved

# Write a trigger which, when the salary of any employee(s) is updated, inserts a single record into this audit table with the total amount of the change across all employees.

Posted on 2010-08-22
754 Views
I had to revise my question since people think it's different.

Table TBL_EMP_AUDIT is defined as follows:

create table TBL_EMP_AUDIT
(auditid int primary key identity(1,1),
notes varchar(200),
delta money)

I need to write a trigger which, when the salary of any employee(s) is updated, inserts a single record into this audit table with the total amount of the change across all employees.

e.g. if five employees were given \$1000 pay cut in a single update statement, the audit table should contain one row with values delta = -5000, notes = ‘Salaries updated’

I found a similar question about it on EE but they had set amounts that the salary will be reduced or added. It has to be variable.

0
Question by:flyguy80
• 5
• 4

LVL 58

Expert Comment

ID: 33497449
From http:Q_26421124.html.
You noted that this was an assignment question.  That is now removed from the question text.

There has been several discussions among the experts about doing homework assignments.  The general conclusion among the experts is to give guidance but not to actually do the homework for the person.  The purpose of homework is for them to learn how to program and if an experts does it for them, they are not learning how to do it for themselves.

Hope these give you general guidelines.  If you are stuck somewhere, shout on that specific issue.

In a trigger, you have the virtual table INSERTED that you can use a select statement on.
SUM() function can be used to get a total from a column across all rows of a table.
See Books Online for the syntax of INSERT statements, to add a record into the audit table.

To put something like £–5000, a mixture of string and numeric, you will need to concatenate two strings using the + operator.  The number needs to be converted to string using CAST(<number expression> AS varchar(10)).  But if it is just numeric, then -5000 from the SUM would be fine.

Table columns can be set up with DEFAULT constraints, which can be an expression like (getdate()) to automatically put the current date when no data is provided.
0

LVL 58

Expert Comment

ID: 33497467
There is also a DELETED table in triggers, that you can compare against the INSERTED table. I would take a SUM from DELETED, and another SUM from INSERTED, the difference of which would be your delta.
0

Author Comment

ID: 33497536
Is the syntax below correct?

CREATE TRIGGER [ddltrg_AUDIT_EMP] ON dbo.TBL_EMP
FOR UPDATE
AS
BEGIN
DECLARE @affected_rows INT;
SELECT @affected_rows =COUNT(*) FROM deleted
DECLARE @pay_cut FLOAT;
SET @pay_cut = salary
DECLARE @delta FLOAT;
SET @delta = @affected_rows * @pay_cut

INSERT INTO  dbo.TBL_EMP_AUDIT
(
InsertDate,
notes,
delta
)
VALUES
(
GETDATE(), -- this is catch the insert time of the your update
'Salaries updated',
@delta
)
END

ENABLE TRIGGER [ddltrg_AUDIT_EMP] ON dbo.TBL_EMP
0

Author Comment

ID: 33497542
or this?

CREATE TRIGGER [ddltrg_AUDIT_EMP] ON dbo.TBL_EMP
FOR UPDATE
AS
BEGIN
DECLARE @affected_rows INT;
SELECT @affected_rows =COUNT(*) FROM deleted
DECLARE @pay_cut FLOAT;
SET @pay_cut = deleted.salary - inserted.salary
DECLARE @delta FLOAT;
SET @delta = @affected_rows * @pay_cut

INSERT INTO  dbo.TBL_EMP_AUDIT
(
InsertDate,
notes,
delta
)
VALUES
(
GETDATE(), -- this is catch the insert time of the your update
'Salaries updated',
@delta
)
END

ENABLE TRIGGER [ddltrg_AUDIT_EMP] ON dbo.TBL_EMP
0

LVL 58

Expert Comment

ID: 33497558
For the 2nd, the insert is fine (syntax), but

sample SUM statement

select SUM(moneycol) from sometable
``````DECLARE @affected_rows INT;

SELECT @affected_rows =COUNT(*) FROM deleted  ---- this

DECLARE @pay_cut FLOAT;

--- you cannot reference deleted.salary outside of select statements

SET @pay_cut = deleted.salary - inserted.salary

DECLARE @delta FLOAT;

--- this logic assumes the pay cuts are all equal

SET @delta = @affected_rows * @pay_cut
``````
0

Author Comment

ID: 33497662
I'm not understanding. Basically if I run this query:

UPDATE TBL_EMP
SET salary = salary -1000

It'll run the trigger that I wrote above which needs to sum the amount that I reduced from salary pay. If the syntax is wrong, then how do I reference the sum of all inserted - the sum of all deleted?

Like this?

CREATE TRIGGER [ddltrg_AUDIT_EMP] ON dbo.TBL_EMP
FOR UPDATE
AS
BEGIN
DECLARE @affected_rows INT;
SELECT @affected_rows =COUNT(*) FROM deleted
DECLARE @delta FLOAT;
SET @delta = SUM(deleted.salary) - SUM(inserted.salary)

INSERT INTO  dbo.TBL_EMP_AUDIT
(
InsertDate,
notes,
delta
)
VALUES
(
GETDATE(), -- this is catch the insert time of the your update
'Salaries updated',
@delta
)
END
0

LVL 58

Expert Comment

ID: 33497690
select sum(salary) from deleted

This query gives you the sum of salary column across all records in the deleted table.

Also, the UPDATE statement could be complex, e.g.

UPDATE TBL_EMP SET salary = salary * 1.04

So individual records may be updated by different \$ amounts, so taking the amount of 1 x number of records - that approach wouldn't work.
0

Author Comment

ID: 33497747
So would this work?

CREATE TRIGGER [ddltrg_AUDIT_EMP] ON dbo.TBL_EMP
FOR UPDATE
AS
BEGIN
DECLARE @affected_rows INT;
SELECT @affected_rows =COUNT(*) FROM deleted
DECLARE @delta FLOAT;
SET @delta = (SELECT SUM(salary) FROM DELETED) - (SELECT SUM(salary) FROM INSERTED)

INSERT INTO  dbo.TBL_EMP_AUDIT
(
notes,
delta
)
VALUES
(
'Salaries updated',
@delta
)
END

ENABLE TRIGGER [ddltrg_AUDIT_EMP] ON dbo.TBL_EMP

UPDATE TBL_EMP
SET salary = salary -1000.00
0

LVL 58

Accepted Solution

cyberkiwi earned 500 total points
ID: 33497764
Depends on your definition of delta.
Normally is is current - previous, so inserted - deleted.
It looks ok otherwise.

You may want to remove @affected_rows, since it is redundant.
0

## Featured Post

### Suggested Solutions

There are some very powerful Data Management Views (DMV's) introduced with SQL 2005. The two in particular that we are going to discuss are sys.dm_db_index_usage_stats and sys.dm_db_index_operational_stats.   Recently, I was involved in a discu…
So every once in a while at work I am asked to export data from one table and insert it into another on a different server.  I hate doing this.  There's so many different tables and data types.  Some column data needs quoted and some doesn't.  What …
Excel styles will make formatting consistent and let you apply and change formatting faster. In this tutorial, you'll learn how to use Excel's built-in styles, how to modify styles, and how to create your own. You'll also learn how to use your custo…
This video gives you a great overview about bandwidth monitoring with SNMP and WMI with our network monitoring solution PRTG Network Monitor (https://www.paessler.com/prtg). If you're looking for how to monitor bandwidth using netflow or packet s…