A client’s second clustered SQL Server instance failed to install: Specified instance via transform is already installed. Here is what I found and the fix.
How to Sort a Varchar Column Storing Integers with Order By? – Interview Question of the Week #206
How do you sort a Varchar column storing integers with Order By when you cannot change the datatype? Here are two simple solutions I shared with a developer.
SQL SERVER – Measuring the Length of VARCHAR and NVARCHAR Columns with COL_LENGTH
Does an NVARCHAR column take twice the space of VARCHAR? Yes. I measure the length of VARCHAR and NVARCHAR columns with COL_LENGTH to show it.
Count a Particular Value Across All Columns in SQL Server
To count a particular value across all columns of a table, use a CASE sum, CROSS APPLY with VALUES, UNPIVOT or UNION ALL. This post tests all four on a staff contact table, compares their reads on 200,000 rows, and builds the column list with dynamic SQL.
SQL SERVER – Cluster Install Failure – Code 0x84cf0003 – Updating Permission Setting for Folder Failed
A SQL Server cluster install failed with code 0x84cf0003: Updating permission setting for folder failed. Here is why volume mount points can cause it.
EXCEPT Operator in SQL Server: Distinct Rows and Differences
The EXCEPT operator returns the rows of one query that are missing from another, with duplicates removed. This post shows the difference between two small order tables, the old WHERE 1 = 0 trick for distinct rows, and how NULLs behave.
The Ascending Key Problem: Estimates for Today’s New Rows
Diagnose ascending key estimates with histogram boundaries, modification counts, and controlled comparisons before updating statistics.