How to Join two tables showing all records Where Table A is Not In Table B - sql

Question

I have a email marketing web application. I want to show which email contacts in (Table B) are not showing up in EmailContacts_Campaign (Table A). In addition, I want to filter table A by the CampaignId field. When I run the below code I get 0 records, yet I know there are a couple of thousand records there. Can anyone tell me where I am messing up?
SELECT * FROM TableA
LEFT JOIN TableB
ON TableA.EmailContactId = TableB.EmailContactId
WHERE TableA.CampaignId = 1
AND TableB.EmailContactId IS NULL
ORDER BY TableB.EmailContactId DESC
I want to show all email contacts in the EmailContact Table that are not showing up in the EmailContactCampaign table. Here is the actual code:
public List<EmailContact> GetNotAssignedContactsForCampaign(int campaignId)
{
string sqlCommand = "SELECT * FROM EmailContactCampaign LEFT JOIN EmailContact";
sqlCommand += " ON EmailContactCampaign.EmailContact_EmailContactId = EmailContact.EmailContactId";
sqlCommand += " WHERE EmailContactCampaign.EmailContact_EmailContactId = " + campaignId.ToString() AND EmailContact.EmailContactId IS NULL ;
sqlCommand += " ORDER BY EmailContact.EmailContactId DESC";
var emailContacts = new List<EmailContact>();
string CS = db.Database.Connection.ConnectionString;
using (SqlConnection con = new SqlConnection(CS))
{
con.Open();
SqlCommand cmd = new SqlCommand(sqlCommand, con);
//Create sql datareader
using (SqlDataReader sqlDataReader = cmd.ExecuteReader())
{
while (sqlDataReader.Read())
{
var emailContact = new EmailContact();
emailContact.Assigned = ((bool)sqlDataReader["Assigned"]);
emailContact.Cell1 = _crypto.DecryptAndSanitize(sqlDataReader["Cell1"] as string);
emailContact.Cell2 = _crypto.DecryptAndSanitize(sqlDataReader["Cell2"] as string);
emailContact.City = _crypto.DecryptAndSanitize(sqlDataReader["City"] as string);
emailContact.Company = _crypto.DecryptAndSanitize(sqlDataReader["Company"] as string);
emailContact.EmailAddress = _crypto.DecryptAndSanitize(sqlDataReader["EmailAddress"] as string);
emailContact.EmailContactId = (int)sqlDataReader["EmailContactId"];
emailContact.FullName = _crypto.DecryptAndSanitize(sqlDataReader["FullName"] as string);
emailContact.Hold = (bool)sqlDataReader["Hold"];
emailContact.Phone1 = _crypto.DecryptAndSanitize(sqlDataReader["Phone1"] as string);
emailContact.Phone2 = _crypto.DecryptAndSanitize(sqlDataReader["Phone2"] as string);
emailContact.State = _crypto.DecryptAndSanitize(sqlDataReader["State"] as string);
emailContact.Status = (Status)sqlDataReader["Status"];
emailContact.Zip = _crypto.DecryptAndSanitize(sqlDataReader["Zip"] as string);
emailContacts.Add(emailContact);
}
}
return (emailContacts);
}
}

Answer 1

Have you tried this?
SELECT * FROM tableB WHERE EmailContactId NOT IN (SELECT EmailContactId FROM tableA)

Answer 2

i think you got 0 probably because of this AND TableB.EmailContactId IS NULL
Please try this one
SELECT * FROM TableA
LEFT JOIN TableB
ON TableA.EmailContactId = TableB.EmailContactId
WHERE TableA.CampaignId = 1
ORDER BY TableB.EmailContactId DESC

Answer 3

I'm sorry my question was not clear enough. Did some digging and found the answer on another post. Sorry but I accidentally closed it and can't find it again. Anyway, here is my implementation of it.
SELECT * FROM EmailContact
WHERE NOT EXISTS
(SELECT * FROM EmailContactCampaign WHERE EmailContactCampaign.EmailContact_EmailContactId = EmailContact.EmailContactId AND EmailContactCampaign.Campaign_CampaignId = 1)

Answer 4

If i understood your question correctly, you are looking for B's that are not in A. But your query will return A's that are not in B. Turn it aroung (tableB left join tableA where a... is NULL)

Answer 5

Your problem was that you had it the wrong way around: your query would return all contacts from EmailContactCampaign that were not in EmailContact.
The correct solution for your problem would look like this:
SELECT * FROM EmailContact
WHERE EmailContactId NOT IN (
SELECT EmailContact_EmailContactId FROM EmailContactCampaign
WHERE Campaign_CampaignId = ?
)
ORDER BY EmailContact.EmailContactId DESC