检查已提交的事务，如果是，则返回一个值

Question

I want to insert a new user (Email address) into a table of users. If successful (no duplicate), insert basic configurations for new user to other tables, and return some data to client. If not successful, receive relevant notification in dataset in C# project.

Here is sample code so you can easily comment on it

ALTER PROCEDURE [dbo].[CreateUser] 
  @Email nvarchar(256),   
  @Password nvarchar(256)   
AS
BEGIN
  declare @UserID uniqueidentifier;
  declare @ConfigID uniqueidentifier;
  declare @TopMostNode uniqueidentifier;

  BEGIN TRANSACTION;
    select @UserID = NEWID();
    select @ConfigID = newid();

    insert into Users (UserID,Email,Password,CurrentConfig) 
      values(@UserID, @Email, @Password, @ConfigID);

    INSERT INTO Configs (ConfigID, OwnerID, DisplayName, LastPrintID)
      VALUES (@ConfigID,@UserID, 'Default Config', 1);

  COMMIT TRANSACTION 
END

Answer 1

Here is one possibility where you return a recordset with the data you require and a flag to indicate whether the user already existed or not.

alter procedure [dbo].[CreateUser]
(
  @Email nvarchar(256)  
  , @Password nvarchar(256)
)
as
begin
  declare @UserID uniqueidentifier, @ConfigID uniqueidentifier, @TopMostNode uniqueidentifier, @UserExists bit = 0;

  select @UserID = UserID, @UserExists = 1 from Users where Email = @Email;

  if @UserExists = 0 begin
    begin transaction;
      set @UserID = newid();
      set @ConfigID = newid();

      insert into Users (UserID, Email, [Password], CurrentConfig) 
        values (@UserID, @Email, @Password, @ConfigID);

      insert into Configs (ConfigID, OwnerID, DisplayName, LastPrintID)
        values (@ConfigID, @UserID, 'Default Config', 1);

    commit transaction 
  end

  -- Return whether the user already exists or not and the user id
  select @UserExists, @UserId

  return 0;
end

Another way to return data to the app is using output parameters eg

alter procedure [dbo].[CreateUser]
(
  @Email nvarchar(256)  
  , @Password nvarchar(256)
  , @UserId uniqueidentifier out
  , @UserExists bit out
)
as
begin
  declare @ConfigID uniqueidentifier, @TopMostNode uniqueidentifier;

  set @UserExists = 0;

  select @UserID = UserID, @UserExists = 1 from Users where Email = @Email;

  if @UserExists = 0 begin
    begin transaction;
      set @UserID = newid();
      set @ConfigID = newid();

      insert into Users (UserID, Email, [Password], CurrentConfig) 
        values (@UserID, @Email, @Password, @ConfigID);

      insert into Configs (ConfigID, OwnerID, DisplayName, LastPrintID)
        values (@ConfigID, @UserID, 'Default Config', 1);

    commit transaction 
  end

  return 0;
end

Answer 2

That code is almost complete. Just need to add a SELECT to return the new keys. In case of an error, you will get an exception. EG:

ALTER PROCEDURE [dbo].[CreateUser] 
  @Email nvarchar(256),   
  @Password nvarchar(256)   
AS
BEGIN
  declare @UserID uniqueidentifier;
  declare @ConfigID uniqueidentifier;
  declare @TopMostNode uniqueidentifier;

  BEGIN TRANSACTION;
    select @UserID = NEWID();
    select @ConfigID = newid();

    insert into Users (UserID,Email,Password,CurrentConfig) 
      values(@UserID, @Email, @Password, @ConfigID);

    INSERT INTO Configs (ConfigID, OwnerID, DisplayName, LastPrintID)
      VALUES (@ConfigID,@UserID, 'Default Config', 1);

  COMMIT TRANSACTION 
  select @UserID UserID, @ConfigID ConfigID;
END