Programming Guide - Actian

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System-defined FunctionsCount Function and NullsThe count function can take as an argument the wildcard character “*”. Thischaracter is used to count the number of rows in a result table, including rowsthat contain nulls. For example, the following statement counts the number ofemployees in department 23:select count(*)from employeewhere dept = 23;You cannot qualify the asterisk (*) argument with all or distinct.Because count(*) counts rows rather than columns, count(*) does not ignorenulls. Consider the following table:NameExemptionsAllen 0Curtiz 2Fleming 4WellmanHitchcocknullnullThe statement:count(exemptions)returns the value “3”, whereas the statementcount(*)returns “5”.With the exception of count, if the argument to an aggregate functionevaluates to an empty set, then the function returns a null. The count functionreturns a zero.How You Can Use the Group By Clause with Aggregate FunctionsThe group by clause allows aggregate functions to be performed on subsets ofthe rows in the table. The subsets are defined by the group by clause.62 <strong>Programming</strong> <strong>Guide</strong>
System-defined FunctionsFor example, the following statement selects rows from a table of politicalcandidates, groups the rows by party, and returns each party's name and theaverage funding for the candidates in that party.select party, avg(funding)from candidatesgroup by party;Restrictions on the Use of Aggregate FunctionsThe following restrictions apply to the use of aggregate functions:• You cannot nest aggregate functions.• You can use aggregate functions only in select or having clauses.• If a select or having clause contains an aggregate function, columns notspecified in the aggregate must be specified in the group by clause, forexample:select dept, avg(emp_age)from employeegroup by dept;This select statement specifies two columns, dept and emp_age, but onlyemp_age is referenced by the avg aggregate function. The dept column isspecified in the group by clause.The Ifnull FunctionThe ifnull function enables you to specify a value, other than a null, that isreturned to your application when a null is encountered. The ifnull function isspecified as follows:ifnull(v1,v2)If the value of the first argument is not null, then ifnull returns the value of thefirst argument. If the first argument evaluates to a null, then ifnull returns thesecond argument.For example, the sum, avg, max, and min aggregate functions return a null ifthe argument to the function evaluates to an empty set. To receive a valueinstead of a null when the function evaluates to an empty set, you can use theifnull function, as in this example:ifnull(sum(employee.salary)/25, -1)Ifnull returns the value of the expression “sum(employee.salary)/25” unlessthat expression is null. If that expression is null, the ifnull function returns -1.Language Elements 63
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Ingres OpenROAD ® 2006Programming
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ContentsChapter 1: Introduction 13I
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Using an Object-oriented Approach t
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How You Can Retrieve Array Informat
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Chapter 12: Managing Event Queues 3
Page 11 and 12: Chapter 17: Preprocessing Your 4GL
Page 13 and 14: Chapter 1: IntroductionThis section
Page 15 and 16: ConventionsConventionsThe following
Page 17: Your Support OptionsYour Support Op
Page 20 and 21: OpenROAD NamesThe rules for these n
Page 22 and 23: OpenROAD Names3. Enclosing field sc
Page 24 and 25: OpenROAD NamesThe following code ex
Page 26 and 27: VariablesThe following illustrates
Page 28 and 29: VariablesIn the first example, film
Page 30 and 31: VariablesOpenROAD checks references
Page 32 and 33: VariablesHow You Can Declare Dynami
Page 34 and 35: VariablesFor example, assume that y
Page 36 and 37: ExpressionsHowever, you cannot use
Page 38 and 39: ExpressionsThe general syntax for h
Page 40 and 41: ExpressionsCurSessionSpecifies, for
Page 42 and 43: ExpressionsString OperatorThe conca
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Page 64 and 65: System-defined FunctionsResult Data
Page 67 and 68: Chapter 3: Writing Scripts and Proc
Page 69 and 70: ScriptsDeclare local variables that
Page 71 and 72: ScriptsUserEventSpecifies a user ev
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Page 75 and 76: ProceduresOpenROAD lets you create
Page 77 and 78: ProceduresReturning from a Procedur
Page 79 and 80: ProceduresExample—Local Procedure
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Page 83 and 84: Calling Procedures• In this call
Page 85 and 86: Calling ProceduresparameterAssigns
Page 87 and 88: How Procedure Handles Work (ProcHan
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Page 96 and 97: How You Can Invoke FramesHow the Cu
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Page 110 and 111: How You Can Invoke FramesThe syntax
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How You Can Run Non-interactive App
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How You Can Reference ObjectsHow Yo
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How You Can Reference ObjectsHow Yo
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How You Can Reference ObjectsUse an
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Using an Object-oriented Approach t
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InheritanceClass RelationshipsYou c
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InheritanceYou can specify a user c
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InheritanceThe Terminate method is
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How You Can Create a User ClassWhen
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How You Can Create a User ClassHow
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How You Can Create a User Class3. G
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How You Can Create a User ClassTo e
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External ClassesHow You Can Use Ext
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External ClassesExample—ActiveX C
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How You Can Manipulate Objects Gene
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Overview of the OpenROAD System Cla
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How You Can Access a Database with
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How You Can Manage TransactionsHow
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How You Can Manage TransactionsDivi
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How You Can Manage TransactionsTo c
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How Programming for Multiple Sessio
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Handling Database ErrorsIn OpenROAD
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Handling Database ErrorsIf a databa
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Handling Database ErrorsFor example
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Handling Database Errorsbeginerr_no
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Arrays and Table Fields—Conceptua
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ArraysBecause an individual attribu
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ArraysDeclaring an array variable d
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ArraysThe following statement puts
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Arraysfor i = custtable.FirstRow to
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ArraysHow You Can Add Rows to an Ar
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ArraysThe inserted row is blank bec
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ArraysThe following code fragment i
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ArraysThese attributes are:AllRowsR
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ArraysAttributes used in a sort can
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ArraysThe format parameter can be a
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Table FieldsTable Fields and Associ
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Table FieldsThe following applicati
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Table FieldsThis syntax references
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Table FieldsFor example, the follow
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Table Field OperationsTable Field C
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Table Field OperationsHow You Can U
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Table Field OperationsWhen you use
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Table Field OperationsBiases can be
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Table Field OperationsThe following
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Table Field OperationsHow You Can T
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Table Field OperationsTableField Me
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Table Field OperationsFor example,
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Table Field OperationsControlling M
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CollectionsCollectionsA collection
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Collections// Open a workbook and p
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Listview_Treeview_DemoImport the De
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Listview FieldsListview FieldsA lis
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Listview FieldsextensionSpecifies a
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Listview FieldsImageIndexSpecifies
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TreeNode and Tree ClassesHeaderClic
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TreeNode and Tree ClassesMaintenanc
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Treeview FieldsHow You Can Build a
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Treeview FieldsThe second window is
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Treeview FieldsThe tree_ex2_class h
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Chapter 9: Working with Images and
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How You Can Work with ImagesThe fol
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How You Can Work with ImagesThe Col
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How You Can Work with ImagesThe Bit
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How You Can Work with Images5. Add
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How You Can Work with Text StringsD
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How You Can Work with Text StringsH
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How You Can Call 3GL ProceduresIn t
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How You Can Use Exec 4GL Statements
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How You Can Link 3GL ProceduresHow
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Sample 3GL ProceduresExec 4GL and E
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How You Can Use Data Entry Error Ha
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Chapter 12: Managing Event QueuesTh
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Event-based ProgrammingThe followin
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Event-based ProgrammingEvent TypesT
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Event-based ProgrammingField Events
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Event-based ProgrammingBecause all
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Event-based ProgrammingThe followin
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Event-based ProgrammingThe resume s
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Event-based ProgrammingNote: The da
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Communicating Between OpenROAD Fram
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How You Can Communicate with an Ext
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How You Can Communicate Between Ope
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How You Can Communicate Between Ope
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Chapter 14: Creating Dynamic Frames
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How You Can Change Field and Frame
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How You Can Create and Modify Field
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How You Can Remove Fields Dynamical
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How You Can Declare a Composite Fie
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How You Can Manipulate Data in Dyna
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How You Can Manage Operations with
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How You Can Build a Frame Dynamical
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Dynamic Statements ConsiderationsDy
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How You Can Write an AssistantNote:
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How You Can Write an AssistantFirst
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How You Can Write an AssistantBecau
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How You Can Ensure Compatibility Be
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Chapter 17: Preprocessing Your 4GL
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PreprocessorGeneral Preprocessor St
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PreprocessorThe #define StatementTh
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Error ProcessingGuidelines for Usin
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Chapter 18: Debugging Your Applicat
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How You Can Test an ApplicationHow
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How You Can Use Break ConditionsTo
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How You Can Use Break Conditions3.
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How You Can Use Break ConditionsWay
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How You Can Use Break ConditionsSet
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How You Can Use Break Conditions•
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How You Can Use Break ConditionsMet
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How You Can Log Trace InformationDa
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How You Can Monitor a Running Appli
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How You Can Monitor a Running Appli
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How You Can Debug Database QueriesT
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How Debugging an Application WorksS
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How Debugging an Application WorksH
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How Debugging an Application WorksW
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How Debugging an Application WorksH
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How Debugging an Application WorksW
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How Debugging an Application WorksL
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How Debugging an Application WorksA
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Appendix A: SQL Syntax SummaryThis
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SQL Syntax Summarygrant all [privil
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OpenSQL Syntax SummaryOpenSQL Synta
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Operating System CommandsThe follow
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BitmapObject classThe BitmapObject
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external classAn external class def
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local variableLocal variables conta
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StringObject classThe StringObject
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Index'' ' (single quotation marks)c
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Attributesdefined • 28referencing
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using to copy data • 244using wit
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application threads • 444array di
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examining values • 473hexadecimal
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Gmoney • 51numeric list • 53pad
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Namesapplication • 21dynamic •
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ReadOps attributesettings • 243Re
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concat function • 54functions •
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event chains • 323event queue •
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