Free Tools for the SQL Server DBA Part 2 - SQL Server Central
http://www.sqlservercentral.com/articles/Tools/64908
Less Than Dot - Blog - The Ten Most Asked SQL Server Questions And Their Answers
http://blogs.lessthandot.com/index.php/DataMgmt/DataDesign/the-ten-most-asked-sql-server-questions--1

Getting all rows from one table and only the latest from the child table

1) Selecting all the values from a table for a particular date 2) Search all columns in all the tables in a database for a specific value 3) Splitting string values 4) Select all rows from one table that don't exist in another table 5) Getting all rows from one table and only the latest from the child table 6) Getting all characters until a specific character 7) Return all rows with NULL values in a column 8) Row values to column (PIVOT) 9) Pad or remove leading zeroes from numbers 10) Concatenate Values From Multiple Rows Into One Column

I've worked with expensive SQL Server and Oracle setups for most of my career. I've defended them viciously against all comers and contrarians. I've participated in late-night guerilla flame wars and drunken bar brawls. And I've sought out with relentless tunnel vision those pieces of propaganda which support my foregone conclusion: that SQL Server and/or Oracle are (or were) the best choices for the organization. I used to be a commercial database advocate. These databases have put food on my table for a dozen years, you see. I am (or was) what you might call an entrenched practicioner, not necessarily an expert, but a practicioner. And in the manner of entrenched practicioners around the world, I've treated you heretics with the sadistic undercutting and poisonous rancor you've deserved! "MySQL?" I would sneer. "PostgreSQL? Thanks, but this a serious project. We need a database we can depend on." Ahem.

googled "why pay for commercial database" and found this among other articles

Are Commercial Databases Worth It? http://bit.ly/Du96H (via @newsycombinator) [from http://twitter.com/tadej/statuses/1664387681]

Se cuestiona la idoneidad de escoger una BD comercial com Oracle o SQL Server frente a sus alternativas Open Source.