Voice of the DBA

Tag: SQLNewBlogger

Creating a User Without a Login

Another post for me that is simple and hopefully serves as an example for people trying to get blogging as #SQLNewBloggers.

This is one of those simple things that many people should be able to do in order to build in better security for their database code. However I’m sure many people haven’t ever built one. I ran into this recently, and thought it would be a great SQLNewBlogger post.

Creating the User

It’s a bit anticlimactic, but creating a user in a database without a login is simple:

CREATE USER UpdateStatsUser
WITHOUT LOGIN WITH DEFAULT_SCHEMA = [dbo];
GO

This creates a new user in my database,

that is not associated wtih a login.

I can assign this user permissions, like any other user.

GRANT CONTROL ON dbo.Authors TO UpdateStatsUser;

I could then use these permissions any other way.

Why would you do this?

A short summary from Pinal Dave, which is pretty good. Essentially you want to give different permissions to a user, without using something like an Application Role, which has a name and password that must be managed. Here, you can allow a user to execute a routine as another, more privileged user, without giving the original user additional permissions.

SQLNewBlogger

This is a really simple post that took my longer to write than create the user. About 10 minutes. I wouldn’t expect most of you to stop here. I’d want a post that shows you understand something about how this user can be used, show me an example of reading or writing a table as a user with this impersonation in action.

References

CREATE USER – https://msdn.microsoft.com/en-us/library/ms173463.aspx

February 8, 2016
Loading a Text File from T-SQL

Another post for me that is simple and hopefully serves as an example for people trying to get blogging as #SQLNewBloggers.

One of the interesting things I’ve had to work on with the Advent of Code puzzles is loading files into SQL Server. Some of the inputs are large strings, but many are files with lines of code that need to be loaded into SQL Server.

I thought this might be a nice, simple SQLNewBlogger post. Do you know how to load a text file? Certainly the Import/Export wizard can work, but can you quickly load a file from T-SQL itself?

If you can’t, go work that out. If you get stuck, come back or search for help.

Loading a Text File

Obviously you need a place to load the file. I created a table for each puzzle, and here is the table for Day 2.

create table Day2_WrappingPresents
( dimensions varchar(12)
)
go

Now ordering doesn’t matter for this puzzle, so I have a very simple table. If ordering mattered, I’d have to do this differently.

To load this file, I’ll use the BULK INSERT command. This takes a table as a target, and optionally has a number of parameters. Since this is a simple load of a simple file with one column of data to a table with one column of data, I can use the defaults.

bulk insert Day2_WrappingPresents
from ‘C:\Users\Steve\Documents\GitHub\AdventofCode\Day 2 – Wrapping\input.txt’

In this case, the insert will load all 1000 rows into the table. A simple query shows this works:

Now I can get on with the rest of my puzzle solution.

SQLNewBlogger

This is a great example of a simple thing that we might not need to do often, but we may need to do at times. Knowing how to do this, a simple operation, showcases that you are improving your SQL Server skills. This post took me about 5 minutes to write.

February 1, 2016
Creating a Database Snapshot
Another post for me that is simple and hopefully serves as an example for people trying to get blogging as #SQLNewBloggers.

I’ve rarely dealt with database snapshots, outside of lab experimentation. They didn’t exist when I did most of my DBA work, and since then we haven’t seen the need for them at SQLServerCentral, though, I may suggest we add them to our deployment process since we can quickly roll back if something breaks.

However, I created one recently for a test and realized that I’d forgotten the syntax. Unlike the quick "create database xx" syntax I often use, with a snapshot I need to be more specific.

The big item that I must specify is the location of the snapshot file. This is the file that gets written to with the copy-on-write process that ensures the original state of the pages when the snapshot is created are still available.

You do need to give the database a logical name as well, which can be anything, but the reference below has suggestions. I’d say that this is bad:

CREATE DATABASE sandbox_snapshot
ON (NAME = MySnap
, FILENAME = ‘h:\SQL Server\MySnap.ss’
)
AS SNAPSHOT OF Sandbox

But this is better

CREATE DATABASE sandbox_snapshot_20150122_1345
ON (NAME = SandBox_Snap_20150122
, FILENAME = ‘h:\SQL Server\MySnap.ss’
)
AS SNAPSHOT OF Sandbox

Because the snapshot is based on an existing database, at a particular point in time, it’s useful to specify the time when the snapshot was created, if possible. While you can get this from metadata, if you have people that look to multiple snapshots for information, it can be handy to know when each is from.

However if you are providing this on a schedule, like daily, for people to report from, you might need to have the same name every day. Think about this, as you cannot rename a snapshot once it’s created.

SQLNewBlogger

When I realized I had to lookup the syntax, I took a few notes and captured code, which meant I combined this writing (< 10 minutes) with other work I was doing.

You should do the same. When you tackle something new, take screenshots, save code, and drop it in a OneNote/EverNote/etc notebook for your weekly blog writing.

Reference

The references I used:
- Create a Database Snapshot – https://msdn.microsoft.com/en-us/library/ms175876.aspx
January 25, 2016
Disabling SQL Server Network Protocols

Another post for me that is simple and hopefully serves as an example for people trying to get blogging as #SQLNewBloggers.

I ran across a question on network protocols recently, which is something I rarely deal with. Often the default setup for SQL Server is fine, but there are certainly times you should add or remove network connectivity according to your environment.

Here’s a short post on turning off (or on) a network protocol for SQL Sever.

What’s Enabled?

The easiest way to verify what’s enabled is to use the SQL Server Configuration Manager. You’ll need administrative permissions on the host to run this, but it’s easy to find.

Once you open it, typically you’ll have a list of the items that can be configured.

We want the SQL Server Network Configuration, which is the server level configuration for this host. The Client configurations are for the host being used a client to connect to a SQL Server.

As you can see here, I have Shared Memory and TCP/IP enabled for this instance, but Named Pipes disabled.

Disabling a Protocol

As you might expect, this is easy. I right click on a protocol, and I can change the status. In this case, I’ll disable Shared Memory

Once I do that, the protocol is disabled. However not on the instance. I’ll get this message.

I need to restart the server. Once that’s done, no one will be able to use Shared Memory on the host.

I can fix this

Of course, I need to restart my instance again.

Checking the Log

When SQL Server starts, quite a bit of configuration information is written into the log. This is useful for troubleshooting in many cases. One of the things you’ll find is the network listeners, as shown here.

This is usually after the database startup information, so if you look, you can see I have some local pipes and some TCP/IP settings here.

SQLNewBlogger

After reading a question, this was less than 10 minutes to write, with making screenshots. However I’ve done this before. If this was your first time, then it might take you longer to research and write, but I bet most DBAs could do this in 30-45 minutes.

January 18, 2016