Multiple "COUNT" checks prior to Data Insert - asp.net

Question

Having a total blonde moment here so apologies in advance...!
I want to carry out two COUNT conditions prior to entering a new customer recorded into a DB. The below code checks to see if the Username is already in use and rejects the registration if this is applicable. I would like to add an additional COUNT to check if the "CustomerEmail", taken from txtEmail already exists in the DB as well.

Answer 1

I would use a stored procedure to do this something like....
And obviously use appropriate data types for the params
CREATE PROCEDURE usp_InsertUser
#FirstName VARCHAR(100)
, #Surname VARCHAR(100)
, #Email VARCHAR(100)
, #Address VARCHAR(100)
, #Town VARCHAR(100)
, #City VARCHAR(100)
, #Postcode VARCHAR(100)
, #ContactNumber VARCHAR(100)
, #Username VARCHAR(100)
, #Password VARCHAR(100)
, #UserAdded INT OUTPUT
AS
BEGIN
SET NOCOUNT ON;
IF NOT EXISTS (SELECT *
FROM [Customer] WITH (UPDLOCK)
WHERE CustomerUserName = #Username)
BEGIN
INSERT INTO [Customer] (CustomerFirstName,CustomerSurname,CustomerEmailAddress,CustomerAddress,CustomerAddressTown,CustomerAddressCity,CustomerAddressPostcode,CustomerContactNumber,CustomerUserName,CustomerPassword)
VALUES (#FirstName, #Surname,#Email, #Address, #Town, #City, #Postcode,#ContactNumber,#Username,#Password)
SET #UserAdded = 1;
END
ELSE
BEGIN
SET #UserAdded = 0;
END
END
Application code would look something like.....
// define connection and command, in using blocks to ensure disposal
using(SqlConnection conn = new SqlConnection(pvConnectionString ))
using(SqlCommand cmd = new SqlCommand("dbo.usp_InsertUser", conn))
{
cmd.CommandType = CommandType.StoredProcedure;
// set up the parameters
cmd.Parameters.Add("#UserAdded", SqlDbType.Int).Direction = ParameterDirection.Output;
cmd.Parameters.Add("#FirstName", SqlDbType.VarChar, 100);
cmd.Parameters.Add("#Surname", SqlDbType.VarChar, 100);
cmd.Parameters.Add("#Email", SqlDbType.VarChar, 100);
// and so on.....
// set parameter values
cmd.Parameters["#FirstName"].Value = txtFirstName.Text;
cmd.Parameters["#Surname"].Value = txtSurname.Text;
cmd.Parameters["#Email"].Value = txtEmail.Text;
// and so on.....
// open connection and execute stored procedure
conn.Open();
cmd.ExecuteNonQuery();
// read output value from #NewId
int UserAdded = Convert.ToInt32(cmd.Parameters["#UserAdded"].Value);
if (UserAdded == 1)
{
Response.Write("User already exists.");
}
conn.Close();
}

Answer 2

Instead of counting all users and adding 2 check just do one exists statement with 2 conditions.
IF NOT EXISTS(select count(*) from [Customer] where CustomerUserName= #name AND CustomerEmail = #email)
BEGIN
INSERT INTO [Customer] (CustomerFirstName,CustomerSurname,CustomerEmailAddress,CustomerAddress,CustomerAddressTown,CustomerAddressCity,CustomerAddressPostcode,CustomerContactNumber,CustomerUserName,CustomerPassword) VALUES (#FirstName, #Surname,#Email, #Address, #Town, #City, #Postcode,#ContactNumber,#Username,#Password)
END