Standard Deviation

Showplan Operator of the Week - Merge Interval

When Fabiano agreed to undertake the epic task of describing each showplan operator, none of us quite predicted the interesting ways that the series helps to understand how the query optimizer works. With the Merge Interval, Fabiano comes up with some insights about the way that the Query optimizer handles overlapping ranges efficiently.

Display More Than 8000 Characters (SQL Spackle)

SQL Server MVP Jeff Moden shows us a quick and dirty bit of SQL Spackle to display the content of VARCHAR(MAX) and NVARCHAR(MAX).

RowCount

Get the rowcount in all tables

BIT of a Problem

The BIT data type is an awkward fit for a SQL database. It doesn't have just two values, and it can do unexpected things in expressions. What is worse, it is a flag rather than a predicate, and so its overuse, along with bit masks, is a prime candidate for being listed as a 'SQL Code Smell'. Joe Celko makes the case.

Count Distinct

CONVERT function

Issues with IsDate()

IsDate function returns 1 for a numeric value

Contiguous Time Periods

It is always more efficient to maintain referential integrity by using constraints rather than triggers. Sometimes it isn't obvious how to do this. Until a recent idea by Alex Kuznetsov, the history table presented problems for checking data that were difficult to solve with constraints. Joe Celko explains.

Before Insert or Update Trigger