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  • Selection condition
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Stored procedures
From version 20, SQL views and the materialized views are available.
The views handled by this function correspond to the former view mechanism. They do not correspond to SQL views or to materialized views.
Runs a view that was created beforehand (can be used to refresh the view data for example). If the view was created by HCreateView with the hViewPostponed constant, HExecuteView must be used to run the view.
Reminder: a view corresponds to the image of a data file at a given time. A view is stored in memory, which insulates it from the modifications performed in the associated data file. A view can be handled like a standard HFSQL data file.
// Runs the Customer34 view
<Result> = HExecuteView(<View> [, <Selection condition>])
<Result>: Boolean
  • True if the view was run,
  • False otherwise. HError returns more details about the problem.
<View>: Character string
Name of view to run. This name was defined with HCreateView.
<Selection condition>: Optional character string
  • New selection condition for the view records (<Selection Condition> replaces the condition specified when creating the view). This selection condition can be an Ansi or Unicode character string.
  • Empty string ("") to avoid modifying the selection condition.

Selection condition

The general syntax of a condition has the following format:
"CustName>'Smith' and ZipCode=34 or ZipCode=32"
The supported operators depend on the type of items used in the condition:
>Greater thanValid for all types
>=Greater than or equal toValid for all types
<Less thanValid for all types
<>Not equal toValid for all types
<=Less than or equal toValid for all types
]ContainsValid for string types only
]=Starts withValid for string types only
~=Almost equal toValid for string types only
=Strictly equal toValid for all types

Notes about the selection condition:
  • Constant strings must be enclosed in single quotes.
  • If an item name is used in the selection condition, it must only contain letters, numbers and underscore characters ("_"). If the item name contains other characters (apostrophe, etc.), the name of the item must be enclosed in double quotes.
    For example: "e_mail@"]'com'
  • Comparisons between strings are performed according to the ASCII value of the characters and not according to the lexicographic value ('a' > 'Z').
  • The binary memos, the composite keys and the subscripted items cannot be part of a selection condition.
  • If a <string constant> contains single quotes (or double quotes), they must be preceded by a backslash (\).
  • All the items of the main data file can be included in the condition (even the ones that are not items of the view).
  • The condition is applied to each virtual record before it is included in the view. Therefore, you cannot specify several mutually excluding conditions for the same record (join). For example:
    • "Date='1997' and Date='1996'" returns no result.
    • "Date>='1996' and Date<='1997'" returns all the records found between 1996 and 1997.
  • This selection condition can be an Ansi or Unicode character string.
Component: wd290hf.dll
Minimum version required
  • Version 9
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Last update: 10/26/2023

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