• Multi condition UPDATE query

    January 27, 2011

    A simple question I've been asked: Is it possible to merge two UPDATE queries, each on different WHERE conditions, into a single query? For example, is it possible to merge the following two UPDATE statements into one? mysql> UPDATE film SET rental_duration=rental_duration+1 WHERE rating = 'G'; Query OK, 178 rows affected (0.01 sec) mysql> UPDATE […]

  • Another use for "top N records per group" query

    January 10, 2011

    A few days ago I published SQL: selecting top N records per group. It just dawned on me that the very same query solved another type of problem I was having a couple years ago. BTW, for reference, Baron Schwartz posted this 4 years ago. There are very interesting approaches in text and in comments. […]

  • SQL: selecting top N records per group

    January 6, 2011

    A while back I presented(*) an SQL trick to present with non-aggregated column on a GROUP BY query, without use of subquery or derived tables. Based on a similar concept, combined with string walking, I now present a query which selects top-n records for each group, ordered by some condition. It will require no subqueries. […]

  • Speaking at the O'Reilly MySQL Conference 2011

    January 3, 2011

    I'm very pleased and humbled to announce that my submission to the upcoming O'Reilly MySQL Conference, April 2011, has been accepted. I will present a 45 minute session titled openark-kit: MySQL utilities for everyday use. In this session, I will present some of the tools in the openark kit. We'll discuss some limitations of the […]

 
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