Using the Caché Managed Provider for .NET - InterSystems ...

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Using Caché Proxy Classesstring personExists = Sample.Person.ExistsId(CacheConnect, ID).ToString()Display.WriteLine("person " + ID + " exists: " + personExists)For a working example, see the Proxy_2_SaveDelete() method in the bookdemos sample program(see The Caché .NET Sample Programs).5.3.3 Closing and Deleting ObjectsThe Close() method disconnects a proxy object from the database without destroying it:person.Close();The Dispose() method destroys the proxy object:person.Dispose();The methods are identical except that Close() does not destroy the object. Neither method changes thepersistent instance in the database.Important:Always use Close() or Dispose() to close a proxy object.Object reference counts are not maintained on the client. Every time the server returnsan object (either by reference or as a return value) its reference count is increased.When Close() or Dispose() are called, the reference count is decreased. The object isclosed on the server when the count reaches 0.Do not use code such as:person = nothing; //Avoid doing this!This closes the proxy object on the client side, but does not decrement the referencecount on the server. This could result in a situation where your code assumes that anobject has been closed, but it remains open on the server.The DeleteId() class method deletes the instance from the database. You can use the ExistsId() methodto make sure that it is gone:CacheStatus sc = Sample.Person.DeleteId(CacheConnect, ID);Display.WriteLine("Delete status: " + sc.IsOK.ToString());Display.WriteLine("person " + ID + " exists: "+ Sample.Person.ExistsId(CacheConnect, ID).ToString());For a working example, see the Proxy_2_SaveDelete() method in the bookdemos sample program(see The Caché .NET Sample Programs).38 Using the Caché Managed Provider for .NET
Using Caché Queries5.4 Using Caché QueriesA Caché Query is an SQL query defined as part of a Caché class. For example, the Sample.Personclass defines the ByName query as follows:Query ByName(name As %String = "") As %SQLQuery(CONTAINID = 1, SELECTMODE ="RUNTIME")[ SqlName = SP_Sample_By_Name, SqlProc ]{SELECT ID, Name, DOB, SSNFROM Sample.PersonWHERE (Name %STARTSWITH :name)ORDER BY Name}In the Sample.Person proxy class, ByName is a class method. It accepts a connection object, andreturns an ADO Provider CacheCommand object that can be used to execute the predefined SQL query:CacheCommand Command = Sample.Person.ByName(CacheConnect);In this example, the Command.Connection property has been set to CacheConnect, andCommand.CommandText contains the predefined ByName query string. To set the Command.Parametersproperty, we create and add a CacheParameter object with a value of A (which will get all recordswhere the Name field starts with A):CacheParameter Name_param = new CacheParameter("name", CacheDbType.NVarChar);Name_param.Value = "A";Command.Parameters.Add(Name_param);The CacheParameter and CacheDataReader ADO Provider classes must be used to define parametersand execute the query, just as they are in an ADO SQL query (see Using SQL Queries with CacheParameter).However, this example will use the query results to access a set of proxy objects.A CacheDataReader object is used to get the ID of each row in the result set. Each ID is used toinstantiate the corresponding Sample.Person proxy object, which is then used to access the data:Sample.Person person;string ID;CacheDataReader reader = Command.ExecuteReader();while (reader.Read()) {ID = reader[reader.GetOrdinal("ID")].ToString();person = Sample.Person.OpenId(CacheConnect, ID);Display.WriteLine(person.Id() + "\t"+ person.Name + "\n\t"+ person.SSN + "\t"+ person.DOB.ToString().Split(' ')[0].ToString());};Using the Caché Managed Provider for .NET 39
Page 1 and 2: Using the Caché ManagedProvider fo
Page 3 and 4: Table of Contents1 The Caché Manag
Page 5 and 6: List of FiguresCaché .NET Binding
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Page 9 and 10: Caché .NET Binding Client/Server A
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