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Bill Karwin's user avatar
Bill Karwin's user avatar
Bill Karwin's user avatar
Bill Karwin
  • Member for 15 years, 10 months
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About

I've been a software engineer since 1987, and my specialty is as an SQL maven. I also have experience programming in Java, Ruby, Python, Go, PHP, Perl, C, JavaScript, and I have many other coding skills.

I've written a book, SQL Antipatterns Volume 1: Avoiding the Pitfalls of Database Programming from Pragmatic Bookshelf, based on the most common SQL problems I've answered on Stack Overflow and other forums, mailing lists, and newsgroups.

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1410
Retrieving the last record in each group - MySQL
Aug 21, 2009
1160
What's the difference between identifying and non-identifying relationships?
Apr 18, 2009
1126
"INSERT IGNORE" vs "INSERT ... ON DUPLICATE KEY UPDATE"
Feb 14, 2009
800
Should I use != or <> for not equal in T-SQL?
Apr 6, 2009
742
How do the Proxy, Decorator, Adapter, and Bridge Patterns differ?
Dec 8, 2008
723
Reason for Column is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause
Dec 22, 2012
679
SQL join: selecting the last records in a one-to-many relationship
Jan 21, 2010
659
Types in MySQL: BigInt(20) vs Int(20)
Jun 28, 2010
656
Is storing a delimited list in a database column really that bad?
Sep 6, 2010
525
Fetch the rows which have the Max value for a column for each distinct value of another column
Sep 23, 2008
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What is [sql-match-all]?
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76
Am I allowed to make a Stack Overflow clone?
45
Why don't relational databases support returning information in a nested format?
30
How to dive into an ugly database?
27
MySQL - How to check for a value in all columns
23
Is the concept of a clustered index in a DB design sensical when using SSDs?