Way back in March 2011, I attended Tech-Ed India 2011 (read my 3 part series here – Part 01, Part 02, Part 03). During Tech-Ed, I learnt about some of the cool new T-SQL debugging enhancements in the next public release of Microsoft SQL Server, SQL 11 (Code Named: “Denali”). In the next couple of posts, I will attempt to summarize these enhancements, and finally provide a ranking of which features I liked best and would tend to use more often once Denali goes into production.
Why so late?
Some of you might be thinking – “Why is this guy posting this stuff so late? We are already in CTP03!” Well, the answer is simple – I believe in using a feature in practice before writing about it. Debuggers are a very powerful set of tools, and it would not be fair to write about something if I could not provide a few helpful tips & pointers.
As a background, you may read my previous posts on T-SQL debugging:
- T-SQL Debugging: A hands-on
- Enabling the T-SQL Debugger
- T-SQL Debugger: Connection Errors & Firewall settings
- T-SQL Debugger: SSMS error – MSDBG2.dll
It is important to remember that the SQL Server Management Studio for SQL 11 “Denali” is based on the Visual Studio 2010 shell. Hence, the debugging features of VS2010 “magically” flow into SSMS.
Debugging in Denali – Breakpoints
Test Script for this session
We will debug the following script in this session on SQL 11 (“Denali”) CTP03. It is a very simple script that loops through for 20 iterations.
DECLARE @iCounter INT = 0
WHILE (@iCounter <= 20)
BEGIN
PRINT 'Hello World! The counter reads: ' + CAST(@iCounter AS VARCHAR(2))
PRINT 'Hello Nakul! The counter reads: ' + CAST(@iCounter AS VARCHAR(2))
SET @iCounter += 1
END
GO
Creating Conditional Breakpoints & Labeling them
One of the major features that was missing in the earlier versions of SSMS was the ability to have conditional breakpoints. In SSMS for Denali, conditional break-pointing is possible. To explore it’s features, let’s start debugging by pressing the F10 key as high-lighted in the Hands-On session. I would re-iterate that debugging in SSMS is not at all different than debugging in VS2010.
To demonstrate the fact, let’s place a breakpoint near the line for “Hello World!”. We will make this a conditional breakpoint, to break only if the value of the counter hits 10.
| Hit F9 to setup the breakpoint on the desired line
Note that the information in the “Breakpoint” window is non-descriptive. Let’s correct that first |
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| Right-click on the breakpoint, and choose “Edit Labels” |  |
| In the “Edit Labels” window, type in a descriptive detail and click “Add”
If pre-existing, you can choose one if you like |
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| On clicking “OK”, notice that the breakpoint can now be identified easily amongst a pile of breakpoints |  |
| Now, right-click on the breakpoint and go to “Condition” |  |
| Add the required expression as a condition and click “OK” |  |
| Notice that in both the “Breakpoints” window & editor window, the breakpoint symbol now has a little "plus (+) sign in it |  |
| Let’s create a “Hit Count” based breakpoint for the second line |  |
| For the test, let’s set this breakpoint to hit at intervals in multiples of 4 – at 4, 8, 12,16 & 20.
Hit OK once done to set the breakpoint |
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| The Breakpoints window would look like the one in the screenshot |  |
Hit “Alt + F5” to run through the sample code. The first breakpoint hit will be “Hello Nakul!” when the hit count is 4. To verify whether the hit is correct or not, you can either use the “Locals” window or the “Immediate” window (Go to Debug –> Windows –> Immediate or press Ctrl+Alt+I):
Hit Alt+F5 again. The next breakpoint to be hit will again be “Hello Nakul!”. Hit Alt + F5 again, and we will hit the “Hello World!” breakpoint and so on.
Searching for specific breakpoints – using Labels to your advantage
Go to Debug->Windows->Breakpoints or press Ctrl+Alt+B to launch the Breakpoints window.
While we only have 2 breakpoints in this session and it is quite easy to remember them, in production code, there might be tens of breakpoints and it might be difficult to remember each one. What’s more, out of all breakpoints, you might want to work with only the breakpoints that are related to a particular operation – an update to a given table, for example.
In the breakpoints window, take the time out to label each breakpoint carefully. You may want to use your labels such that each label identifies a particular group of operations in question – for example, a label can be – “Updating Production”, “Updating Sales Orders” and so on.
Notice the addition of a “Search” box in the Breakpoint window. The “Search” box allows us to search on a specific column or on all visible columns of the breakpoint window.
Choosing “All Visible” in the “In Column” drop-down, let’s type in “World” in the “Search” box and hit Enter. Notice that SSMS will take the other breakpoints off the list. Clearing the search results will bring them back.
Concluding for today…
I believe that we have just barely scratched the surface of the debugging features available in SQL 11 (“DenaIi”). In my next post, I will cover how to Export & Import Breakpoints – a boon in collaborative development environment. After that, I will cover “Data Points”, which is in itself a very exciting development to the debugger.
Until we meet next time,
Be courteous. Drive responsibly.
SQLTwins by Nakul Vachhrajani 