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Stored procedures
HDescribeKey (Function)
In French: HDécritClé
HDescribeKey is kept for backward compatibility (this function will still be supported in the forthcoming version).
From version 8, to describe a key, you must:
  1. Declare an item object.
  2. Define all the properties of the item with the HFSQL properties.
  3. Use HDescribeItem to validate the item creation.
The documentation about HDescribeKey available in WINDEV 5.5 is as follows.
Note: From version 19, HFSQL is the new name of HyperFileSQL.
 
Purpose
Describe a simple or composite key in a temporary data file in Hyper File format
Syntax
HDescribeKey(<LogicalNameHFFile>,<KeyItemName> [,<KeyItemList> [,<Duplicate>]])
  • <LogicalNameHFFile> is a character string containing the name of the logical data file
  • <NameKeyItem> is a character string containing the name of the key (up to 100 characters)
  • <KeyItemList> is an optional character string containing the list of items found in the key.
    • For a composite key, the items are separated by a comma in <ListKeyItem>: <NameItem1>, <NameItem2>, ...
    • For a simple key, <Item List> contains the name of the key.
  • <Duplicates> is an optional boolean used to find out whether the key is unique or multiple:
    • set to True for multiple key (with duplicates)
    • set to False for a unique key
    By default, <Duplicate> is set to True.
Details
The key is built according to the parameters passed to HDescribeKey.
If <ListKeyItem> is not specified, <NameKeyItem> must be a file item
If several keys are specified, the simple keys must be defined before the composite keys. The error HF 508 occurs if a composite key is described before a simple key.
<Duplicates> is set to True by default. Therefore, if <Duplicate> is not specified, the key is a multiple key.
Notes
  • The data file must have been described by HDescribeFile.
  • The items included in the key must have been described beforehand by HDescribeItem.
  • To describe a unique simple key, the syntax is as follows:
    HDescribeKey(<FileName>,<Key_Name>, <Key Name>, False)
  • HDescribeKey cannot be used to describe the key of a data file that was created with the description editor
  • HDescribeKey does not exist in external language.
  • HDescribeKey must not be called after one of the following functions used on the same data file: HOpen, HCreation or HCreationIfNotFound.
Minimum required version
  • Version 9
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