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First of all you should have a Telerik.DataAccess.Core nuget package. When you add it in your project, visual studio intellisense should recognize his usages and show you option to add the new using. However, the namespace is Telerik.OpenAccess.Data.Common.OAParameter and it is in Telerik.OpenAccess assembly.
You can read more for the parameterized queries here
I hope the provided information is helpful.
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