OK, I’ve talked about Primary Keys and Foreign Keys. Now let’s talk about Referential Integrity. Basically this just means that any Foreign Key value in one table has to have that same value defined in the table where that Foreign Key is the Primary Key. Let’s look at two tables, and try to explain this…
Month: March 2009
SET TRANSACTION ISOLATION LEVEL
Like I’ve mentioned before, unless you use SET TRANSACTION ISOLATION LEVEL, the server will default to READ COMMITTED. What this means is by default, your queries will only be able to interact with records that have been committed. If another query is affecting those records, you’re not able to see them in any way. I…
SQL Session – DTS to SSIS
If you’re not already a member of the Charlotte SQL Server User Group, go now and sign up. This group is a great resource of knowledge and connections to the SQL Server community in Charlotte, NC. Their plan is to get together once a month and discuss a new and interesting topic on SQL Server….
SQL 102 – Indexes With Included Columns
I’ve shown you how to create indexes, CLUSTERED versus NONCLUSTERED indexes, today I want to build on that. Let’s say you have a lookup query that takes names, and returns an ID for that name, you can actually build your query in a way where it would look up that data using just an index. …