Sql 如何连接显示表A不在表B中的所有记录的两个表

我有一个电子邮件营销网络应用程序。我想显示（表B）中的哪些电子邮件联系人没有出现在EmailContacts_活动（表A）中。此外，我还希望通过“活动ID”字段筛选表A。当我运行下面的代码时，我得到0条记录，但我知道那里有几千条记录。谁能告诉我我把事情搞砸了吗

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

我想在

EmailContact

表中显示所有未在

EmailContactCampaign

表中显示的电子邮件联系人。以下是实际代码：

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);
            }
        }

public List getnotassignedcontactsforcompaign（int-activitid）
{
string sqlCommand=“选择*来自EmailContactCampaign LEFT加入EmailContact”；
sqlCommand+=“ON-EmailContactCampaign.EmailContact\u EmailContactId=EmailContact.EmailContactId”；
sqlCommand+=“其中EmailContactCampaign.EmailContact_EmailContactId=“+campaignId.ToString（）和EmailContact.EmailContactId为空；
sqlCommand+=“按EmailContact.EmailContactId描述订购”；
var emailContacts=新列表（）；
字符串CS=db.Database.Connection.ConnectionString；
使用（SqlConnection con=newsqlconnection（CS））
{
con.Open（）；
SqlCommand cmd=新的SqlCommand（SqlCommand，con）；
//创建sql数据读取器
使用（SqlDataReader SqlDataReader=cmd.ExecuteReader（））
{
while（sqlDataReader.Read（））
{
var emailContact=新的emailContact（）；
emailContact.Assigned=（（bool）sqlDataReader[“Assigned”]）；
emailContact.Cell1=\u crypto.DecryptAndSanitize（sqlDataReader[“Cell1”]作为字符串）；
emailContact.Cell2=\u crypto.DecryptAndSanitize（sqlDataReader[“Cell2”]作为字符串）；
emailContact.City=_crypto.decryptandsonize（sqlDataReader[“City”]作为字符串）；
emailContact.Company=_crypto.decryptandsonize（sqlDataReader[“Company”]作为字符串）；
emailContact.EmailAddress=\u crypto.DecryptAndSanitize（sqlDataReader[“EmailAddress”]作为字符串）；
emailContact.EmailContactId=（int）sqlDataReader[“EmailContactId”]；
emailContact.FullName=\u crypto.DecryptAndSanitize（sqlDataReader[“FullName”]作为字符串）；
emailContact.Hold=（bool）sqlDataReader[“Hold”]；
emailContact.Phone1=\u crypto.DecryptAndSanitize（sqlDataReader[“Phone1”]作为字符串）；
emailContact.Phone2=\u crypto.DecryptAndSanitize（sqlDataReader[“Phone2”]作为字符串）；
emailContact.State=_crypto.decryptandsonize（sqlDataReader[“State”]作为字符串）；
emailContact.Status=（Status）sqlDataReader[“Status”]；
emailContact.Zip=_crypto.decryptandsonize（sqlDataReader[“Zip”]作为字符串）；
emailContacts.Add（emailContact）；
}
}
返回（电子邮件联系人）；
}
}

您试过这个吗

SELECT * FROM tableB WHERE EmailContactId NOT IN (SELECT EmailContactId FROM tableA)

---

我认为您得到0可能是因为这

和TableB.EmailContactId为NULL

请试试这个

SELECT * FROM TableA
LEFT JOIN TableB 
ON TableA.EmailContactId = TableB.EmailContactId
WHERE TableA.CampaignId = 1
ORDER BY TableB.EmailContactId DESC

---

对不起，我的问题不够清楚。做了一些挖掘，在另一篇帖子上找到了答案。对不起，我不小心把它关了，再也找不到了。无论如何，这是我的实现

SELECT * FROM EmailContact
WHERE NOT EXISTS
(SELECT * FROM EmailContactCampaign WHERE EmailContactCampaign.EmailContact_EmailContactId = EmailContact.EmailContactId AND EmailContactCampaign.Campaign_CampaignId = 1)

---

如果我正确理解了您的问题，您正在查找不在A中的B。但您的查询将返回不在B中的A。将其转过来（

tableB left join tableA，其中A…为NULL

）您的问题在于您的查询方式错误：您的查询将返回

EmailContactCampaign

中不在

EmailContact

中的所有联系人

您的问题的正确解决方案如下所示：

SELECT * FROM EmailContact
WHERE EmailContactId NOT IN (
  SELECT EmailContact_EmailContactId FROM EmailContactCampaign
  WHERE Campaign_CampaignId = ?
)
ORDER BY EmailContact.EmailContactId DESC

---

你的问题中是否有关于

SELECT*FROM TableA

的引文，或者这是打字错误？