Andy Warren

I started my SQL journey here at SQLServerCentral as one of the founders, helping to build a place to share and learn that continues to thrive under the editorial guidance of my friend Steve Jones. I've done a lot of volunteer work over the years ranging from our local SQL group (oPASS, SQLOrlando) to serving on the Board of Directors of PASS to designing and building the framework of SQLSaturday (which has gone on to produce more than 1000 locally managed events since we started in 2007). These days I manage a DBA team, but over the years I've been a trainer, consultant, contractor, and DBA. I'm rarely present on social media, the best way to contact me is here, LinkedIn, or via email.

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Blog Post

PASS Update #16

A one topic post this time. As a candidate for Vice President of Marketing for PASS this year I asked...

2009-10-18

628 reads

Technical Article

Sparse Columns – ConvertSVtoXML & XMLToResv

Not very often I run across something with zero matches in a search engine, but had it happen recently. I had set up a simple demo of a sparse column set and happened to look at the execution plan, was interested to see that the Compute Scalar was backed by ConvertSVtoXML. This was on a select from a table with one row, and then, being a little more curious, updated it with an xml fragment I saw a call to ConvertXMLtoResv. I’d venture that those serve to convert back/forth from XML storage.

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2009-10-15

1,219 reads

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Adding new column with DEFAULT II

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Question of the Day

Adding new column with DEFAULT II

Which number did the two COUNT(*) return: 

DROP TABLE IF EXISTS #tmp
CREATE TABLE #tmp (id INT NOT NULL)

INSERT INTO #tmp (id) 
SELECT gs.value
  FROM GENERATE_SERIES(1, 5) AS gs

ALTER TABLE #tmp ADD my_value INT NOT NULL CONSTRAINT df_tmp_my_value DEFAULT 1

SELECT COUNT(*)  FROM #tmp AS t WHERE my_value = 1

ALTER TABLE #tmp DROP CONSTRAINT df_tmp_my_value

ALTER TABLE #tmp ADD CONSTRAINT df_tmp_my_value DEFAULT 2 FOR my_value

SELECT COUNT(*)  FROM #tmp AS t WHERE my_value = 1

See possible answers