Error 130 says you cannot perform an aggregate function on an expression containing an aggregate, like AVG(COUNT()). A derived table gets around it.
SQL Server emergency? Email pinal@sqlauthority.com with URGENT in the subject line.
SQL SERVER – Binary Sequence Generator – Truth Table Generator
A script that builds a 512 row truth table with its decimal value and binary sequence, using CROSS JOINs on a bit table. Add or remove joins to resize it.
SQL SERVER – DBCC commands List – documented and undocumented
The full list of documented and undocumented DBCC commands with their syntax, plus how DBCC TRACEON(2520) and DBCC HELP show all of them in Query Analyzer.
Last Line of a SQL Script: The Joke Every DBA Has Lived
The last line of a SQL script decides whether your work is saved, rolled back, or still holding locks. Here are the classic endings and how to check them.
SQUARE: Expect a float Result From Numeric Inputs
SQUARE accepts numeric inputs convertible to float and returns float. Explicit decimal display keeps this small example readable without claiming exact decimal multiplication.
SQL SERVER – Query to Find First and Last Day of Current Month – Date Function
One query to find the First and Last Day of Current Month in SQL Server, plus the last day of the previous month and the first day of the next.
SQL SERVER – UDF – Function to Parse AlphaNumeric Characters from String
UDF_ParseAlphaChars keeps only the alphanumeric characters in a string and strips everything else using PATINDEX and STUFF. A handy function, with a test.
SQL Server slow? Let's fix it together in about four hours.
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Who We Are
Pinal Dave is an SQL Server Performance Tuning Expert and independent consultant with over 24 years of hands-on experience. He holds a Masters of Science degree and numerous database certifications.
Pinal has authored 19 books and 125 Pluralsight courses. To freely share his knowledge and help others build their expertise, Pinal has also written more than 5,800 database tech articles on his blog at https://blog.sqlauthority.com.
Pinal is also a CrossFit Level 1 Trainer (CF-L1) and CrossFit Level 2 Trainer (CF-L2).
Nupur Dave is a social media enthusiast and an independent consultant. She primarily focuses on the database domain, helping clients build short and long-term multi-channel campaigns to drive leads for their sales pipeline.
Shaivi Pinalkumar Dave is a book author and a women’s artistic gymnast.

