Towering Queries

A co-worker today couldn't figure out how a column, ostensibly being set to null held a value of 0 instead of null. I looked at the populating code and couldn't find anywhere a null was being replaced with a value of zero, so the most likely candidate was a default constraint on the column. Turned out he wasn't sure how to find default constraints on columns. The easiest way is to use the sp_help function on the table name, or highlight the table name and hit alt-f1. exec sp_help myTable At the bottom, you'll find all the constraints on the table, including default constraints. If however your table is not part of the dbo schema (as the Aventureworks sample database is fond of doing) you won't be able to use those methods on the table as it assumes the object exists in the 'dbo' schema. Instead, you can access the data via the Dynamic Management Views (DMVs) like this: select TableName = object_name(c.object_id), DefaultConstraintName = d

Several times a year I get asked something like "Can SQL do regular expressions"? The answer is essentially no (I know, I know, CLRs). But while SQL statements can't make sure of regular expressions to search through table data, you CAN use them in the course of creating and editing SQL scripts. SQL Server Management Studio as well as Visual Studio, which the later versions of SQL Server use as their IDE support regular expressions in find-and-replace operations. If you're wholly unfamiliar with regular expressions, there are tons of resources out there to help you learn. Some good info can be found at www.regular-expressions.info . I personally bought a book called Introducing Regular Expressions which I found quite useful. It's not my intent to teach regular expression here, but to show you how to find a regex character you need and give you some find-and-replace regular expressions I use almost daily. First things first, SQL Server uses some funky notation

For those of you who may not have known, there’s a cool trick you can do in Visual Studio or SSMS; the alt-drag marquee. Many of these functions can be handled with fine and replace with or without regular expressions, but sometimes those are more trouble than it’s worth. The basics of alt-drag are this . Say I have a block of text, such as a comment block of a procedure which I want to replace all at once. Hold alt and drag to the bottom right, and you get a marquee area which respects x/y coordinates rather than just lines and indentation. Now the cool part. If you’ve ever used copy-paste with these marquees, you’ll find they work… oddly. However like any good Jedi, you can turn your enemies weakness into your strength. Say for example, I forgot to type select statements for a derived table like this: You could use find replace to replace “all” with “all select’, you could use a series of copy/paste commands and down arrow keys, or this: Create a zero-wid