SQL Server nested triggers - sql

Question

I have three tables:
CREATE TABLE Rents
(
RentID INT IDENTITY NOT NULL PRIMARY KEY,
StartDate SMALLDATETIME,
EndDate SMALLDATETIME,
Price MONEY,
RealEstateID INT UNIQUE NOT NULL,
DealMadeByEmployeeID INT NOT NULL,
CONSTRAINT CHK_Rents CHECK (Price > 0 AND EndDate > StartDate),
CONSTRAINT FK_Rents_EstatesBasicInfo
FOREIGN KEY (RealEstateID) REFERENCES EstatesBasicInfo(RealEstateID),
CONSTRAINT FK_Rents_Employees
FOREIGN KEY (DealMadeByEmployeeID) REFERENCES Employees(EmployeeID)
);
CREATE TABLE Purchases
(
PurchaseID INT IDENTITY NOT NULL PRIMARY KEY,
DateBought SMALLDATETIME,
Price MONEY CHECK (Price>0),
RealEstateID INT UNIQUE NOT NULL,
DealMadeByEmployeeID INT NOT NULL,
CONSTRAINT FK_Purchases_EstatesBasicInfo
FOREIGN KEY (RealEstateID) REFERENCES EstatesBasicInfo(RealEstateID),
CONSTRAINT FK_Purchases_Employees
FOREIGN KEY (DealMadeByEmployeeID) REFERENCES Employees(EmployeeID)
);
CREATE TABLE EmployeesSalary
(
EmployeeID INT NOT NULL PRIMARY KEY,
CurrentSalary MONEY DEFAULT 0,-- на процент
MonthlySalesMade INT DEFAULT 0,
MonthlyRentsMade INT DEFAULT 0,
CONSTRAINT FK_EmployeesSalary_Employees
FOREIGN KEY (EmployeeID) REFERENCES Employees(EmployeeID),
CONSTRAINT CHK_EmployeesSalary
CHECK (CurrentSalary >= 0 AND MonthlySalesMade >= 0 AND MonthlyRentsMade >= 0)
);
Each of them has a trigger
CREATE TRIGGER tr_EmployeesSalaryPurchasesUpdate --при INSERT в Purchases таблицата
ON Purchases
AFTER INSERT
AS
BEGIN
UPDATE EmployeesSalary
SET EmployeesSalary.MonthlySalesMade = EmployeesSalary.MonthlySalesMade + 1
WHERE EmployeesSalary.EmployeeID IN (SELECT inserted.DealMadeByEmployeeID
FROM inserted
WHERE DateBought IS NOT NULL)
END
--Update на MonthlyRentsMade
GO
CREATE TRIGGER tr_EmployeesSalaryRentsUpdate --при INSERT в Rents таблицата
ON Rents
AFTER INSERT
AS
BEGIN
UPDATE EmployeesSalary
SET MonthlyRentsMade = MonthlyRentsMade + 1
WHERE EmployeesSalary.EmployeeID IN (SELECT inserted.DealMadeByEmployeeID
FROM inserted
WHERE StartDate IS NOT NULL)
END
The problem comes when I want to add a trigger to EmployeesSalary:
CREATE TRIGGER tr_EmployeesSalaryCurrentSalary
ON EmployeesSalary
AFTER INSERT
AS
BEGIN
UPDATE EmployeesSalary
SET CurrentSalary = CurrentSalary + ((MonthlySalesMade + MonthlyRentsMade) * 200)
WHERE EmployeeID IN (SELECT i.EmployeeID
FROM inserted AS i);
END
I want when I get an insert in the EmployeesSalary (by the other two triggers), the CurrentSalary to be updated (depending on the EmployeeID). The trigger cause any errors but it doesn't work. (I think this is called nested triggers not sure...) Where is my mistake?

Answer 1

I would prefer to use a computed column instead of a trigger for something like this. Here is an example. I also added ISNULL around the two columns in case you have a NULL. Otherwise the computation will always be NULL.
alter table EmployeesSalary
add ComputedSalary as CurrentSalary + ((isnull(MonthlySalesMade, 0) + isnull(MonthlyRentsMade, 0)) * 200) persisted

Answer 2

Since this is an after-insert trigger (recursion won't occur on update table). I think where you are making a mistake is using NULL values in calculations so I would try this:
CREATE TRIGGER tr_EmployeesSalaryCurrentSalary
ON EmployeesSalary
AFTER INSERT
AS
BEGIN
UPDATE es
SET CurrentSalary = coalesce(i.CurrentSalary, 0) + ((coalesce(i.MonthlySalesMade, 0) + coalesce(i.MonthlyRentsMade, 0)) * 200)
from EmployeesSalary as es
inner join inserted AS i
on i.EmployeeID = es.EmployeeID
END
Also, I don't like IN statements so I'm joining instead.