TRIGGER AFTER INSERT SELECT MIN(COUNT) insert ID - sql-server

Question

I'm trying to create a trigger after an insert on the eventss table. The trigger should select the Bcoordinator_ID from the bookingCoordinator table where they have the minimum number of occurrences in the eventss table.
Here's my table data followed by the trigger. It doesn't like the minCount in the values, I think it's looking for and int.
DROP TABLE eventsBooking
CREATE TABLE eventsBooking
(
EBK INT NOT NULL IDENTITY(100, 1),
booking_ID AS 'EBK'+CAST( ebk as varchar(10)) PERSISTED PRIMARY KEY,
bookingDate DATE,
Bcoordinator_ID VARCHAR (20),
eventss_ID VARCHAR (20) NOT NULL
)
INSERT INTO eventsBooking
VALUES ('2015-01-07 11:23:00', NULL, 'EVT100');
Eventss table:
EVT INT NOT NULL IDENTITY(100, 1),
eventss_ID AS 'EVT' + CAST(evt as varchar(10)) PERSISTED PRIMARY KEY,
eventsName varchar(50),
noOfStages SMALLINT,
noOfRounds SMALLINT,
eventsDate DATE,
entryFee DECIMAL (7,2),
venue_ID VARCHAR (20) NOT NULL,
judges_ID VARCHAR (20)
INSERT INTO eventss
VALUES ('Swimming Gala 2015', '3', '7', '2015-01-07 09:00:00', '35.00', 'VEN101', 'JUD100');
CREATE TABLE bookingCoordinator
(
BCO INT NOT NULL IDENTITY(100, 1),
Bcoordinator_ID AS 'BCO'+CAST( bco as varchar(10)) PERSISTED PRIMARY KEY,
forename varchar(20) NOT NULL,
familyName varchar(50)
)
INSERT INTO bookingCoordinator VALUES ('Steve', 'Wills');
Trigger:
CREATE TRIGGER TRGinsertJudge
ON [dbo].[eventss]
AFTER INSERT
AS
BEGIN
SET NOCOUNT ON;
INSERT INTO dbo.eventsBooking (Bcoordinator_ID, bookingDate, Eventss_ID)
VALUES(minCount, getdate(), 100)
SELECT MIN(COUNT(Bcoordinator_ID)) AS minCount
FROM eventsBooking
END

Answer 1

You can't do an aggregation of an aggregation i.e. MIN(COUNT(1))
If you just want the Bcoordinatior_ID with the least counts in eventsBooking, do this
select top 1 bcoordinator_id
from eventsBooking
group by bcoordinator_id
order by count(1) asc
And you don't use VALUES() in an INSERT INTO ... SELECT statement
Also, in your current code, since eventsBooking.bcoordinator_id is always null, you need to join to the actual table of bookingCoordinators to return booking coordinators without any events booked.
So your complete trigger statement should be
INSERT INTO dbo.eventsBooking (Bcoordinator_ID, bookingDate, Eventss_ID)
select
top 1
bookingcoordinator.bcoordinator_id, getdate(), 100
from bookingCoordinator left join eventsBooking
on bookingCoordinator.Bcoordinator_ID = eventsBooking.Bcoordinator_ID
group by bookingcoordinator.bcoordinator_id
order by count(1) asc