Question on the Data Type Conversion chart

Question

Post reply

Question on the Data Type Conversion chart

dfalso

SSC-Addicted

Points: 491
More actions
October 12, 2016 at 3:07 pm

#400862

found here: https://msdn.microsoft.com/en-us/library/ms191530.aspx
I had assumed that, when the grid cell is Explicit (blue filled-in square), that meant that any comparison between those two data types needed to involve explicitly CASTing/CONVERTing one to the other. Then I started testing.
My first test was XML to nvarchar. The chart indicates an explicit conversion type. I tested it, and indeed, my test example fails:
declare @lhvar xml = '<root><element>4</element></root>';
declare @rhvar nvarchar(100) = '<root><element>4</element></root>';
print
case
when @lhvar = @rhvar then 1
else 0
end
Msg 402, Level 16, State 1, Line 29
The data types xml and nvarchar are incompatible in the equal to operator.
Then I started trying some other combinations listed as Explicit:
declare @lhvar datetime = datefromparts(1900,1,1);
declare @rhvar money = 0;
print
case
when @lhvar = @rhvar then 1
else 0
end
1
declare @lhvar hierarchyid = '/1/10/';
declare @rhvar varchar(10) = '/1/10/';
print
case
when @lhvar = @rhvar then 1
else 0
end
1
This grid has been up since forever, so I feel like I must be understanding it wrong. Can someone help clarify?
Thanks very much.
Forum Etiquette: How to post Reporting Services problems

[/url]

Forum Etiquette: How to post data/code on a forum to get the best help - by Jeff Moden
[/url]

How to Post Performance Problems - by Gail Shaw
[/url]

mister.magoo SSC-Forever Points: 47068 More actions · Answer 1

~~datetime to money and hierarchyid to varchar are listed as implicit...~~

sorry, got those round the wrong way...

money to datetime and varchar to hierarchyid are both implicit, so that is what is happening...

MM

select geometry::STGeomFromWKB(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