Using Caché Objects - InterSystems Documentation

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Objects and SQL The identity column has the name “ID” , unless the object has a property named “ID” ; in that case, the identity column has “ID1” as its name. (If there are ID and ID1 properties, the identity column has “ID2” as its name, and so on.) 13.2.1.1 ID Column Constraints Though the ID appears as a column in the projection, there is no need to create an index based on it, as it is already the IDKEY for the table; further, it has no equivalent property, so an index created specifically for a class' SQL projection is not meaningful for the class itself. Additionally, you cannot perform UPDATE or INSERT operations on it, since Caché generates ID values automatically. For instance, here is the syntax to add a new instance of a class through its projection (where the ID column is created from the class OID): INSERT INTO PERSON (FNAME, LNAME)VALUES (:fname, :lname) and not: INSERT INTO PERSON (ID, FNAME, LNAME)VALUES (:id, :fname, :lname) Because the ID field is handled automatically, you do not need to refer to it explicitly. 13.2.2 Properties When projected, most properties appear in a relational table as columns (fields), where the column takes its name from the property; the exception is arrays, which are projected as child tables by default. All a class' properties are projected, aside from the following exceptions: • Transient properties • Calculated properties • Private properties • Multidimensional properties For information on managing the projection of transient or calculated properties, see Transient and Calculated Properties. 116 Using Caché Objects
The Object-SQL Projection 13.2.2.1 Property Names and Column Names If you want to give a property's projected column a different name, use the property keyword SQLFIELDNAME. For instance, if there is a %String property called “select,” you would define its projected name with the following syntax: Property select As %String [ SqlFieldName = selectfield ]; If a property's name is an SQL reserved word, you need to specify a different name for its projection. 13.2.2.2 Column Numbers for Properties Caché automatically assigns a unique column number for each property. If you wish to control column number assignments, you can specify the column for a property's projection. To do this, use the property keyword SQLCOLUMNNUMBER, as in the following example: Property RGBValue As %String [ SqlColumnNumber = 3 ]; The value you specify for SQLCOLUMNNUMBER must be an integer greater than 1 (one) and specifies the property's column number in the projected table. If you use the SQLCOLUMNNUMBER keyword without an argument, Caché assigns a column number that is not preserved and that has no permanent position in the table's columns. If any property has an SQL column number specified, then Caché assigns column numbers for the other properties. The starting value for the assigned column numbers is the number following the highest SQL column number specified. The value of the SQLCOLUMNNUMBER keyword is inherited. 13.2.2.3 Data Type Properties Data type properties are projected as fields using the property's SQL category (defined with the SQLCATEGORY keyword) and any of its parameters. Both relational and object access use the same data type classes, invoke the same data type methods to perform data validation and conversions, and use data type parameter values in the same way. This is true for both system-provided and user-written data type classes. For example, the following property definition: Property Name As %String(MAXLEN = 30);} is projected as a field in a relational table containing a string with a maximum length of 30 characters. Using Caché Objects 117
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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
Page 77 and 78: Index Collation 9.2 Index Collation
Page 79 and 80: 10 Using Objects with Caché Object
Page 81 and 82: Executing Methods 10.1.3 Executing
Page 83 and 84: 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: The Object-SQL Projection 13.2 The
Page 131 and 132: The Object-SQL Projection • The p
Page 133 and 134: If the list for a particular instan
Page 135 and 136: Triggers are, however, fired by the
Page 137 and 138: 14 Relationships A relationship is
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 176 and 177: The Caché Data Population Utility
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The Caché Data Population Utility
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The Caché Data Population Utility
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Using Callback Methods Since differ
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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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