HBuildKeyValue (Function)

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When to use HBuildKeyValue?
Generic search
Building a composite key used in a filter with bounds
Building a composite key without using HBuildKeyValue

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HBuildKeyValue (Function)

In french: HConstruitValClé

Not available with this kind of connection

Builds the value of a composite key to implement a filter (HFilter) or to perform a search (HReadSeekFirst, HReadSeekLast, etc.).

This function can be replaced with an array of values, easier to use. For example:

HReadSeekFirst(FileName, LINKEDCOMPKEY, ["Last name", "First name"])

Are equal to:

HReadSeekFirst(FileName, LINKEDCOMPKEY, ...
	HBuildKeyValue(FileName, LINKEDCOMPKEY, "Last name", "First name"))

Tip To browse a data file using a compound key, use FOR EACH on compound key (syntax 5).

For more details on composite keys in WINDEV, see Composite keys.

Reminder: Compound keys are binary strings whose contents cannot be displayed directly.

Example

See additional examples

bufSoughtVal is Buffer

// Build the composite key
bufSoughtVal = HBuildKeyValue(Customer, LASTNAME_FIRSTNAME, "MOORE", "Vince")

// Build a String/Integer composite key
bufSoughtVal = HBuildKeyValue(Customer, LASTNAME_CUSTNUM, "MOORE", 12128)

// Build an Integer/Integer composite key
bufSoughtVal = HBuildKeyValue(Order, ORDERID_ORDERID, 12119,593)

Syntax

<Result> = HBuildKeyValue(<Data file> , <Composite key> , <Value of components>)

<Result>: Buffer

Value of the composite key.

<Data file>: Character string

Name of the HFSQL data file used.

<Composite key>: Character string

Name of the item corresponding to the composite key

<Value of components>: Character string

Value that will be assigned to each component of the composite key. This parameter has the following format:
<Component 1>, <Component 2>, ..., <Component N>
For example: "MOULIN", "Françoise"..

Remarks

When to use HBuildKeyValue?

HBuildKeyValue can be used to perform searches on binary string keys linked to composite keys.

For example:

FileA file:
COMPKEY is a composite key of FileA. Composition: FileA.Last name+FileA.First name
FileB file:
LINKEDCOMPKEY is a binary string key linked to FileA.COMPKEY

Performing a search on the value of the composite key:

HReadSeekFirst(FileB, LINKEDCOMPKEY, HBuildKeyValue(FileA, COMPKEY, ...
		"Last name", "First name"))

bufKey is Buffer
bufKey = HBuildKeyValue(FileA, COMPKEY, "Last name", "First name")
HReadSeekFirst(FileB, LINKEDCOMPKEY, bufKey)

HReadSeekFirst(FileB, LINKEDCOMPKEY, FileA.COMPKEY)

if FileA is positioned on the record to search for in FileB.

You can also use an array of values instead of HBuildKeyValue:

HReadSeekFirst(FileB, LINKEDCOMPKEY, ["Last name", "First name"])

Generic search

When a generic search is performed, there is no need to define the values of all the components. Only the first n values are required (n being included between 1 and the number of key components, including bounds).

Building a composite key used in a filter with bounds

To build the value of a composite key used in a filter, call HBuildKeyValue.

If the lower bound and the upper bound of the filter must be identical, the hMinVal and hMaxVal constants must be used to fill the bounds.
The following example is used to find all the records of Customer file corresponding to "Vince Moore":
```
HFilter(Customer, ...
	HBuildKeyValue(Customer, LastNameFirstName, "Moore", "Vince") + hMinVal, ...
	HBuildKeyValue(Customer, LastNameFirstName, "Moore", "Vince") + hMaxVal)
```
If the lower bound and the upper bound must be identical and if some key components are not specified, the hMinVal and hMaxVal constants must be used to fill the bounds.
The following example is used to find all the records of Customer file corresponding to "Moore":
```
HFilter(Customer, LastNameFirstName, ...
	HBuildKeyValue(Customer, LastNameFirstName, "Moore" + hMinVal), ...
	HBuildKeyValue(Customer, LastNameFirstName, "Moore" + hMaxVal))
```

Remarks:

hMinVal is equivalent to Charact(0)
hMaxVal is equivalent to Charact(255)

Building a composite key without using HBuildKeyValue

You can use an array of values to build the value of a composite key without using HBuildKeyValue.
For example:

HReadSeekFirst(FileB, LINKEDCOMPKEY, ["Last name", "First name"])

Component: wd300hf.dll