SQL Server error in c# string or binary data will be truncated. insert statement conflict with foreign key

Question

create table [User]
(
    userId int IDENTITY(1,1) primary key ,
    UserName nvarchar(30) unique,
    gender nvarchar(2),
    check( gender in ('M','F')),
    email nvarchar(40),
    DOB date
)

create table User_Auth
(
    uName nvarchar(30),
        foreign key (uName) references [User](UserName),
    pass nvarchar(30)
)

ALTER PROCEDURE [dbo].[CHECKREGISTERCREDENTIALSFORUSER]
    @USRNAME NVARCHAR(30),
    @DATE_OF_BIRTH DATE,
    @EMAIL NVARCHAR(50),
    @PASSWORD NVARCHAR(50),
    @GENDER NVARCHAR(5),
    @enterflag int output
AS
BEGIN
    SET @enterflag = 0;

    IF NOT EXISTS (SELECT UserName FROM [User] u WHERE u.UserName = @USRNAME)
    BEGIN
        IF (@DATE_OF_BIRTH <= GETDATE())
        BEGIN
            INSERT INTO [User] (UserName, gender, email, DOB) 
            VALUES (@USRNAME, @GENDER, @EMAIL, @DATE_OF_BIRTH)

            INSERT INTO [User_Auth] (uName, pass) 
            VALUES (@USRNAME, @PASSWORD)

            SET @enterflag = 1;
        END
        ELSE
        BEGIN
            PRINT 'invalid birth date entered';
        END
    END
    ELSE
    BEGIN
        PRINT 'username is taken';
    END
END

---

public static int Signup(string uname, string password, DateTime DOB, string email, string genders)
{
    SqlConnection con = new SqlConnection(connectionString);
    con.Open();

    SqlCommand cmd;
    int result = 0;

    try
    {
        if (con != null && con.State == ConnectionState.Open)
        {
            cmd = new SqlCommand("CHECKREGISTERCREDENTIALSFORUSER", con);
            cmd.CommandType = System.Data.CommandType.StoredProcedure;

            cmd.Parameters.Add("@USRNAME", SqlDbType.NVarChar, 30).Value = uname;
            cmd.Parameters.Add("@PASSWORD", SqlDbType.NVarChar, 50).Value = password;
            cmd.Parameters.Add("@DATE_OF_BIRTH", SqlDbType.Date).Value = DOB;
            cmd.Parameters.Add("@GENDER", SqlDbType.NVarChar, 5).Value = email;
            cmd.Parameters.Add("@EMAIL", SqlDbType.NVarChar, 50).Value = genders;
            cmd.Parameters.Add("@enterflag", SqlDbType.Int).Direction = ParameterDirection.Output;

            cmd.ExecuteNonQuery();

            result = Convert.ToInt32(cmd.Parameters["@enterflag"].Value);
        }
    }
    catch (SqlException ex)
    {
        Console.WriteLine("SQL Error" + ex.Message.ToString());
        result = -1; //-1 will be interpreted as "error while connecting with the database."
    }
    finally
    {
        con.Close();
    }

    return result;
}

Here is the C# code - I can't figure out what is wrong - I get an error. There is not out of bound input in procedure parameters. Size of parameters in stored procedure is same as written in code. It is supposed to return 1 if sign up is successful. Moreover in my procedure I am adding into parent table and then to child table, still I get an error of

Insert statement conflict with foreign key constraint

Answer 1

The values for email and gender are mixed around when you set the parameters, so you're actually setting the email value to the gender in the database and vice versa.

cmd.Parameters.Add("@GENDER", SqlDbType.NVarChar, 5).Value = email;
cmd.Parameters.Add("@EMAIL", SqlDbType.NVarChar, 50).Value = genders;

should be

cmd.Parameters.Add("@GENDER", SqlDbType.NVarChar, 5).Value = genders;
cmd.Parameters.Add("@EMAIL", SqlDbType.NVarChar, 50).Value = email;

Additionally, in the User table gender is defined with length 2, but in the stored procedure it is declared length 5. Yet, you use check (gender in ('M', 'F')) which is a single char.

If you're only accepting a single character for gender , you could update both the User table definition and stored proc to accept a single char for gender .