Using Caché Globals - InterSystems Documentation

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Using Multidimensional Storage (Globals)// clear ^Data in case it has dataKill ^Data// fill in ^Data with sample dataFor i = 1:1:100 {// Set each node to a random person's nameSet ^Data(i) = ##class(%PopulateUtils).Name()}// loop over every node// Find first nodeSet key = $Order(^Data(""))While (key '= "") {// Write out contentsWrite "#", key, " ", ^Data(key),!}// Find next nodeSet key = $Order(^Data(key))3.5.1.2 Additional $ORDER ArgumentsThe Caché ObjectScript $ORDER function takes optional second and third arguments. The secondargument is a direction flag indicating in which direction you wish to traverse a global. The default,1, specifies forward traversal, while –1 specifies backward traversal.The third argument, if present, contains a local variable name. If the node found by $ORDER containsdata, the data found is written into this local variable. When you are looping over a global and you areinterested in node values as well as subscript values, this operates more efficiently.3.5.2 Looping Over a GlobalIf you know that a given global is organized using contiguous numeric subscripts, you can use a simpleFor loop to iterate over its values. For example, in Caché Basic:For i = 1 To 100Print ^Data(i)Nextor the equivalent in Caché ObjectScript:For i = 1:1:100 {Write ^Data(i),!}Generally, it is better to use the $ORDER function described above: it is more efficient and you donot have to worry about gaps in the data (such as a deleted node).3.5.3 The $QUERY FunctionIf you need to visit every node and subnode within a global, moving up and down over subnodes, usethe Caché ObjectScript $QUERY function. (Alternatively you can use nested $ORDER loops).22 Using Caché Globals
The $QUERY function takes a global reference and returns a string containing the global referenceof the next node in the global (or "" if there are no following nodes). To use the value returned by$QUERY, you must use the Caché ObjectScript indirection operator (@).For example, suppose you define the following global:Set ^Data(1) = ""Set ^Data(1,1) = ""Set ^Data(1,2) = ""Set ^Data(2) = ""Set ^Data(2,1) = ""Set ^Data(2,2) = ""Set ^Data(5,1,2) = ""The following call to $QUERY:SET node = $QUERY(^Data(""))sets node to the string “^Data(1)” , the address of the first node within the global. Then, to get thenext node in the global, call $QUERY again and use the indirection operator on node:SET node = $QUERY(@node)At this point, node contains the string “^Data(1,1)” .The following example defines a set of global nodes and then walks over them using $QUERY,writing the address of each node as it does:Kill ^Data // make sure ^Data is empty// place some data into ^DataSet ^Data(1) = ""Set ^Data(1,1) = ""Set ^Data(1,2) = ""Set ^Data(2) = ""Set ^Data(2,1) = ""Set ^Data(2,2) = ""Set ^Data(5,1,2) = ""// now walk over ^Data// find first nodeSet node = $Query(^Data(""))While (node '= "") {Write node,!// get next nodeSet node = $Query(@node)}Copying Data within Globals3.6 Copying Data within GlobalsTo copy the contents of a global (entire or partial) into another global (or a local array), use the CachéObjectScript MERGE command.Using Caché Globals 23
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Page 10 and 11: Introduction1.3 Use in Applications
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Page 22 and 23: Using Multidimensional Storage (Glo
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Using Caché Globals - InterSystems Documentation

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