How to trigger a table to change the value of another table column
<p>I've created three tables.</p>

<pre><code>CREATE TABLE Clients
(
    ClientID INT IDENTITY(1,1) PRIMARY KEY,
    First_Name VARCHAR(50) NOT NULL,
    Last_Name VARCHAR(50) NOT NULL,
)
CREATE TABLE Reservation
(
    ReservationID INT IDENTITY(1,1) PRIMARY KEY,
    ClientID INT FOREIGN KEY (ClientID) REFERENCES Clients(ClientID),
    Reservation_paid VARCHAR(3) DEFAULT 'NO',
)
CREATE TABLE Payment
(
    Payment_ID INT IDENTITY(1,1) PRIMARY KEY,
    ClientID INT FOREIGN KEY (ClientID) REFERENCES Clients(ClientID),
    ReservationID INT FOREIGN KEY (ReservationID) REFERENCES Reservation(ReservationID),
)
</code></pre>

<p>I would like to change the value of the column Reservation_paid to YES at the Reservation table whenever the Client does pay the reservation, and i want to do it automatically with trigger.</p>

<p>Example: If the <code>ClientID</code> at the Reservation table exists at the Payment table automatically the value of the Reservation_paid will set to YES.
Thank you in advance.</p>