Unfortunately your requirements are quite difficult:
- Split string into three components based on different delimiters
- Convert various components to integers and apply arithmetic to these
- Concatenate all the different components to get one adjusted string
Based on this the following expression will work:
=CInt(Left(Fields!hrs_apprvd.Value, InStr(Fields!hrs_apprvd.Value, ".") - 1))
* 24
+ CInt(Mid(Fields!hrs_apprvd.Value
, InStr(Fields!hrs_apprvd.Value, ".") + 1
, InStr(Fields!hrs_apprvd.Value, ":") - InStr(Fields!hrs_apprvd.Value, ".") - 1))
& ":" & Right(Fields!hrs_apprvd.Value
, Len(Fields!hrs_apprvd.Value) - InStr(Fields!hrs_apprvd.Value, ":"))
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This works for your one example but you might need to adjust slightly for your larger dataset.
You could also simplify the expression by adding a set of calculated fields for smaller expressions like Left(Fields!hrs_apprvd.Value, InStr(Fields!hrs_apprvd.Value, ".") - 1)
and then reference the calculated field in the table expression.
You can see the expression gets complicated very quickly - applying the transformation out of SSRS would also be worth investigating.