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i have store login_time and logout_time in i have to store difference of logout_time-login_time intable.what i can do.i have try following but i can't do...

SqlCommand cmd3 = new SqlCommand("update logininfo set totaltime=logouttime-logintime where log_id=" + logid, cnn);
Updated 7-Jan-13 9:26am

1 solution

Why store something that you have already, in the sense that you can calculate it whenever you need to? Storing it as separate information just increases your database size and provides a route for error to creep in - as it does - when somehow the difference between the In and Out times, and the stores value do not match.

SELECT DATEDIFF(second, logintime, logouttime) as loggedInSeconds FROM logininfo

If you really must store it, then you can use the same command:

UPDATE logininfo SET totaltime=DATEDIFF(second, logintime, logouttime)

But I wouldn't do it myself.
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__TR__ 7-Jan-13 14:10pm    
Was about to post the same solution.
I guess you read my mind and posted it :laugh:
OriginalGriff 7-Jan-13 14:14pm    
Damn! There must be a hole in my tin-foil helmet...:laugh:
Sergey Alexandrovich Kryukov 7-Jan-13 15:44pm    
No, you just miscalculated the skin layer thickness, for such a high-frequency radiation. You just need to use thicker foil for your helmet. Upgrade it as soon as possible, as I'm already sensing what you are up to... (don't worry, I won't tell anyone). My 5, by the way.
fjdiewornncalwe 7-Jan-13 14:11pm    
+5. Same thing I was going to say.

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