Problem with trigger

[asafe]

Let's say I have a table called TBPedido wich has foreigns keys of other tables:TBPratoPrincipal,TBBebida and TBAperitivo. Each of three tables have a codPreco field that stores the price of a product.
In TBPedido I want to calculate the final price by adding the codPreco. I did a trigger, but it does not work:

CREATE TRIGGER triggerTriste On dbo.TBPedido 
after INSERT,UPDATE As    
 Declare @total Decimal(7,2),@cod2 Int ,@cod3 Int,@cod4 Int
 SELECT @cod2=codPrato,@cod3=codBebida,@cod4=codAperitivo FROM inserted  
 If (@cod2 Is Not Null) 
 Begin
  SET @total= @total +(SELECT codPreco FROM TBPratoPrincipal WHERE idPrato =@cod2) 
 End
 If (@cod3 Is Not Null)
 Begin
  SET @total= @total +(SELECT codPreco FROM TBBebida WHERE idBebida = @cod3)
 End
 If (@cod4 Is Not Null)
 Begin
  SET @total= @total +(SELECT codPreco FROM TBAperitivo WHERE idAperitivo = @cod4)       
 End
 UPDATE P 
 SET precoTotal= @total
 FROM TBPedido P
 INNER JOIN inserted D On P.idNumeroPedido= D.idNumeroPedido
GO

[WingedPanther]

Is this SQL Server? It doesn't look quite right.
CREATE TRIGGER

[asafe]

It was supposed to be sql server thing.
Any ideas why is it wrong?

[WingedPanther]

Are you getting any error messages? Also, what is the structure of the tables?

[asafe]

Nope, I don't receive an error. I do:
insert into TBPedido values(1,1,1,1,0);
And where is zero was supossed to become the final price.

USE BDRestaurante;

CREATE TABLE TBPratoPrincipal(
 idPrato Int Not Null,
 codNomeItem VarChar(70) Not Null,
 codPreco Decimal(6,2) Not Null,
 quantidade Int
);

CREATE TABLE TBBebida(
 idBebida Int Not Null,
 codNomeItem VarChar(70) Not Null,
 codPreco Decimal(6,2) Not Null,
 quantidade Int,
 alcoolica Int
);

CREATE TABLE TBAperitivo(
 idAperitivo Int Not Null,
 codNomeItem VarChar(70) Not Null,
 codPreco Decimal(6,2) Not Null,
 quantidade Int
);

CREATE TABLE TBPedido(
 idNumeroPedido Int Not Null,
 codPrato Int,
 codBebida Int,
 codAperitivo Int,
 precoTotal Decimal(7,2)
);

CREATE TABLE TBCardapio (
 idNomeItem VarChar(70) Not Null,
 preco Decimal(6,2) Not Null,
 tipo VarChar(15) Not Null, 
 descricao VarChar(100),
 CONSTRAINT pkIdNomeItem Primary Key(idNomeItem,preco)
);
ALTER TABLE TBPratoPrincipal
Add CONSTRAINT pkIdPrato Primary Key(idPrato),
    CONSTRAINT fkCodNomeItem3 Foreign Key (codNomeItem,codPreco)  
     REFERENCES TBCardapio(idNomeItem,preco) On UPDATE no action On DELETE cascade
                     
ALTER TABLE TBBebida 
Add CONSTRAINT pkIdBebida Primary Key(idBebida),
 	 CONSTRAINT fkCodNomeItem Foreign Key(codNomeItem,codPreco)
 	  REFERENCES TBCardapio(idNomeItem,preco) On UPDATE no action On DELETE cascade

ALTER TABLE TBAperitivo 
Add CONSTRAINT pkIdAperitivo Primary Key(idAperitivo),
    CONSTRAINT fkCodNomeItem2 Foreign Key(codNomeItem,codPreco)  
     REFERENCES TBCardapio(idNomeItem,preco) On UPDATE no action On DELETE cascade

ALTER TABLE TBPedido
Add CONSTRAINT pkIdNumeroItem Primary Key(idNumeroPedido),
    CONSTRAINT fkCodPrato Foreign Key(codPrato)
     REFERENCES TBPratoPrincipal (idPrato) On UPDATE no action On DELETE cascade,   
    CONSTRAINT fkCodBebida Foreign Key (codBebida)
     REFERENCES TBBebida (idBebida) On UPDATE no action On DELETE no action,
    CONSTRAINT fkCodAperitivo Foreign Key(codAperitivo)
     REFERENCES TBAperitivo(idAperitivo) On UPDATE no action On DELETE no action

And then some inserts, views and the trigger I said. I'm afraid the whole design is wrong, what become this trigger very important.

[asafe]

Hahaha I did minor changes and it worked:

CREATE TRIGGER triggerTriste On dbo.TBPedido 
For INSERT,UPDATE As    
 Declare @total Decimal(7,2),@cod2 Int ,@cod3 Int,@cod4 Int 
 SET @total =0.0
 SELECT @cod2=codPrato,@cod3=codBebida,@cod4=codAperitivo FROM inserted  
 If @cod2 Is Not Null 
  SET @total= @total +(SELECT codPreco FROM TBPratoPrincipal WHERE idPrato =@cod2) 
 If @cod3 Is Not Null
  SET @total= @total +(SELECT codPreco FROM TBBebida WHERE idBebida = @cod3)
 If @cod4 Is Not Null
  SET @total= @total +(SELECT codPreco FROM TBAperitivo WHERE idAperitivo = @cod4)       
 UPDATE P 
 SET precoTotal= @total
 FROM TBPedido P
 INNER JOIN inserted D On P.idNumeroPedido= D.idNumeroPedido     
GO