Using Caché Objects - InterSystems Documentation

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Objects and SQL SELECT ID,Name,Title,TheCompany->Name FROM Employee ORDER BY Name The multi-valued side is not projected as a field (Multi-valued relationships are state-less on disk and SQL does not deal with in-memory objects). Instead, you must perform a simple join based on the multi-valued side's ID value and the single-valued side's reference field: SELECT c.Name, e.Name FROM Company c, Employee e WHERE e.TheCompany = c.ID ORDER By 1,2 A single-valued relationship with cardinality of ONE is projected to SQL as a FOREIGNKEY with NOACTION specified for UPDATE and DELETE. If the cardinality of the single-valued relationship is PARENT then the table projected from the class containing the relationship is “adopted” as a child table by the table projected from the type class of the single-valued relationship. 124 Using Caché Objects
14 Relationships A relationship is an association between two objects, each of a specific type; to create a relationship between two objects, each must have a relationship property, which defines its half of the relationship. For example, a Company class may define a one-to-many relationship with an Employee class. In this case, there may be zero or more Employee objects associated with each Company object. Caché relationships have the following characteristics: • Relationships are binary, that is a relationship is defined either between two, and only two, classes or between a class and itself). • Relationships can only be defined for persistent classes. • Relationships must be bi-directional, that is both sides of a relationship must be defined. • Currently, Caché supports two types of relationship: one-to-many (independent) and parent-to-children (dependent). One-to-one and many-to-many relationships are not supported at this time. • Relationships automatically provide referential integrity; unlike a reference (or objectvalued) property, the value of the relationship is constrained to be correct (that is, there are no dangling references). • Relationships automatically manage their in-memory and on-disk behavior. • Relationships provide superior scaling and concurrency over object collections. • Relationships are visible to SQL as foreign keys. See the Object-SQL Projection for more information on this topic. Using Caché Objects 125
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Using Caché Objects Version 5.2 01
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Table of Contents 1 Introduction to
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7 Properties ......................
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13.1 Inheritance and SQL ..........
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20.8 %OnNew .......................
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List of Figures Embeddable Objects
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1 Introduction to Caché Objects Th
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1.2 Class Definitions and the Class
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Development Tools Caché Class Libr
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• The Caché EJB Binding—a vers
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2 Object-Oriented Database Developm
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Encapsulation Caché exploits inher
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3 The Caché Object Model The Cach
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Referring to an Object — OREF, OI
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Types of Classes 3.2.1 Transient Ob
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Types of Classes Embeddable Objects
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A class inherits all of the specifi
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2. It resolves inheritance—it det
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Caché Classes • Class Parameters
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Caché Classes ClientDataType Descr
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Caché Classes Internally, this wor
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Packages Class Packages Any of thes
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Packages Letting the compiler resol
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Packages • “%Library” —any
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Methods where count and state are d
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Methods 6.4 Method Language You hav
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Methods 6.6 Instance and Class Meth
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Methods Write dog.Speak() Which cou
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Properties 7.1 Property Keywords Yo
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Properties Property Behavior The pr
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Properties 7.5 Attribute Properties
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Properties You can manipulate a col
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8 Class Queries Class queries provi
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Query Basics Final Specifies that s
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Caché ObjectScript. These queries
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The data in Row is the result of ex
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9 Indices Indexes provide a mechani
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Index Collation 9.2 Index Collation
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10 Using Objects with Caché Object
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Executing Methods 10.1.3 Executing
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Opening Objects 10.3 Opening Object
Page 85 and 86: where oref is the OREF of the speci
Page 87 and 88: For example, to populate the Home p
Page 89 and 90: change the second vaccination recor
Page 91 and 92: There are two types of array proper
Page 93 and 94: Saving Objects 10.5 Saving Objects
Page 95 and 96: mation. Again, this method deletes
Page 97 and 98: Set rset = ##class(%ResultSet).%New
Page 99: Executing Queries // Create a Resul
Page 102 and 103: Data Types 11.1 Available Types Cac
Page 104 and 105: Data Types • INDEXSUBSCRIPTS —
Page 106 and 107: Data Types CLIENTDATATYPE Values Va
Page 108 and 109: Data Types SQLCATEGORY Values Value
Page 110 and 111: Data Types The property is restrict
Page 112 and 113: Object Persistence 1. Its primary (
Page 114 and 115: Object Persistence Note: In a multi
Page 116 and 117: Object Persistence // Open person "
Page 118 and 119: Object Persistence For example: //
Page 120 and 121: Object Persistence If a persistent
Page 122 and 123: Object Persistence The storage clas
Page 125 and 126: 13 Objects and SQL A key aspect of
Page 127 and 128: The Object-SQL Projection 13.2 The
Page 129 and 130: The Object-SQL Projection 13.2.2.1
Page 131 and 132: The Object-SQL Projection • The p
Page 133 and 134: If the list for a particular instan
Page 135: Triggers are, however, fired by the
Page 139 and 140: Relationship Basics the relationshi
Page 141 and 142: An Invoice class class MyApp.Invoic
Page 143: 14.4 Persistent Behavior of Relatio
Page 146 and 147: Streams Stream data may be stored i
Page 148 and 149: Streams 15.2.2 Copying Data between
Page 150 and 151: Streams Set stream=##class(%Stream.
Page 153 and 154: 16 Class Projections Class projecti
Page 155 and 156: RemoveProjection The RemoveProjecti
Page 157 and 158: 17 Object Synchronization Object sy
Page 159 and 160: About Updates • If two changes re
Page 161 and 162: About Updates Two Synchronized Data
Page 163 and 164: • classname is a quoted string th
Page 165 and 166: Set Status = TargetSyncSet.Import(f
Page 167 and 168: 18 Method Generators A powerful fea
Page 169 and 170: Method Generator Context 6. It copi
Page 171: Implementing Method Generators 3. A
Page 174 and 175: The Caché Data Population Utility
Page 182 and 183: Using Callback Methods Since differ
Page 184 and 185: Using Callback Methods ReturnValue
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Using Callback Methods 20.6 %OnDele
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Using Callback Methods 20.10 %OnRol
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21 Object-Specific ObjectScript Fea
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##this Syntax >Do ##class(Package.C
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##super Syntax 21.4 ##super Syntax
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You can override a property's defau
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Dynamic Dispatch 22.2 Content of Me
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Dynamic Dispatch %DispatchMethod ca
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23 Class Definition Classes The Cac
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You can get detailed information ab
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Internet Classes addressed to , its
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Internet Classes For more informati
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Object Concurrency Setting 1 2 3 4
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Object Concurrency Note: You can us
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