I have two tables with a lot of data. I have to compare them and find out if there are data in table 1 that does not exist in table 2.

Well. I could use this script:

SELECT
name
FROM
table1
WHERE
name NOT IN (SELECT name FROM table2) 

 But since it´s a lot of data in those tables, it will take a while. This script will do it faster: 

SELECT
tbl2.name
FROM
table1 tbl1
RIGTH OUTER JOIN table2 tbl2 ON tbl1.name = tbl2.name
WHERE
tbl1.name IS NULL

Have you ever had problems when logging on to an database with SQL Server Manager. The manager is slow. Almost frozen. There is a little bit strange solution to this problem. 

Open Internet Explorer. Go to Internet Options -> Security and uncheck 'Check for publishers certificate revocation'. Viola...That´s it :) 

Recently I needed to find out if one of my tables contained
duplicates. It resulted in this script:
SELECT Name, COUNT(Name) AS NoOfDuplicates
FROM tblCustomers
GROUP BY Name
HAVING (COUNT(Name) > 1)
I select the name and no of occurrences in my table.
I only select those who have more than one occurrence