How to know the email address is available in the database

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Hi all,

How to know the email address is available in the database while doing registration

Thanks

Posted 3-Sep-11 9:39am

3796068

Updated 3-Sep-11 9:44am

Simon Bang Terkildsen

v2

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Simon Bang Terkildsen · Answer 1 · 2011-09-03T09:47:00

Run a query selecting the rows or COUNT where the email is the same as the input email.

E.g.

C#

SqlCommand command = new SqlCommand("SELECT COUNT(*) FROM users u WHERE u.email = :EMAIL", myConnection);
command.Parameters.Add(":EMAIL", SqlDbType.VarChar).Value = inputEmail;
int count = (int) command.ExecuteScalar();
if(count != 0)
{
    // The email is already used
}

Abhijit Jana · Answer 2 · 2011-09-03T09:50:00

Solution 2

During the registration, you can validate the database and check if the email id is exist of not. You can also take help of AJAX or JQuery to do it behind the scene.

Posted 3-Sep-11 9:50am

Abhijit Jana

Wendelius · Answer 3 · 2011-09-03T09:50:00

If I understood your question correctly, it's a quite broad question. It would include at least the following steps:

create a table for existing accounts containing the email addresses
when a new registration is going on:

create a connection
create a command
define a select statement checking for the email existence. Something like:

SQL

select count(*) from account where email = @email

check if the result is 0. If it is, the email address is already registered
complete the registration
add the new email address to new account row (remember possible case-sensitivity in the database)
commit the changes

let the user know if the operation was successful

Some of the classes needed for this (for Sql Server if that is used):

How to know the email address is available in the database

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