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Functions and Expressions
Use HCL Link functions and expressions to create component rules and map rules.
Lookup and reference functions
These function search operates by scanning the appropriate set of items in sequence, attempting to match the logical condition.
LOOKDOWN
The LOOKDOWN function sequentially searches a series beginning at the end of the series, returning the last member of the series that meets a specified condition.

Functions and Expressions
Use HCL Link functions and expressions to create component rules and map rules.
- Expressions and evaluations
  The documentation provided here describes HCL Link functions and expressions. Functions and expressions are used to create component rules and map rules.
- Using functions
  A function is an expression that generates an output by performing a certain operation on one or more inputs.
- Syntax of a function
  The following is an example of a function:
- Function argument syntax
  Arguments typically have some restrictions on the expression used for that argument.
- Character-set encoding functions
  Functions that use the HCL Link EXIT architecture convert data to the native character set of the platform as part of the function call.
- General functions
  There are several general functions you can call from map rule to process input.
- Bidirectional functions
  Bidirectional languages such as Arabic and Hebrew are languages in which the text is presented to the user ordered from right to left, but numbers and Latin alphabetic strings within the text are presented left to right.
- Bit manipulation and testing functions
  You can use this function to manipulate and to test a bit in a binary number.
- Cache functions
  Use cache functions to specify a value for each of the cache variables defined for a flow, and additionally, to alter an already specified value for a cache variable.
- Conversion functions
  You can use this function to convert an expression from one datatype to another datatype.
- Date/time functions
  You can use this function to perform various operations on date and time.
- Error handling functions
  You can use this function in evaluating the type of error during map execution.
- External interface functions
  You can use this function to retrieve data from a database from within in a map rule.
- Flow functions
  Use Flow functions to specify a value for each of the flow variables defined for a flow, and additionally, to alter an already specified value for a flow variable.
- Inspection functions
  You can use this function to test and inspect the object.
- Logical functions
  Logical functions provide a way to use logical conditions to display one of several values.
- Lookup and reference functions
  These function search operates by scanning the appropriate set of items in sequence, attempting to match the logical condition.
  - CHOOSE
    The CHOOSE function returns the object within a series whose position in the series corresponds to a specified number.
  - DBLOOKUP
    The DBLOOKUP function executes an SQL statement against a database.
  - DBQUERY
    The DBQUERY function executes an SQL statement against a database.
  - DDEQUERY
    The DDEQUERY function allows you to interface to other Windows applications such as Trading Partner PC, Excel, and so forth, provided that certain criteria are met.
  - EXTRACT
    Use EXTRACT whenever you need only particular members of a series returned-those that meet a certain condition. An example might be only POs that contain back-ordered items.
  - GETANDSET
    You can use GETANDSET when you have an input file that keeps track of control information that serves as an input to your map and the control information in the file needs to be updated based on processing that occurs in your map.
  - GETDIRECTORY
    The GETDIRECTORY function returns the full path (directory) for the compiled map file or the source or destination associated with a specified card object.
  - GETITXUID
    The GETITXUID function returns a universally unique identifier (UUID).
  - GETLOCALE
    The GETLOCALE function returns the locale setting of the computer.
  - GETFILENAME
    The GETFILENAME function returns the file name for a file adapter source or target of a specified card object. Without an argument, it returns the adapter command associated with the active source or destination.
  - GETPARTITIONNAME
    You can use GETPARTITIONNAME when you need to know the name of the partition to which the data for the given object belongs.
  - GETRESOURCEALIAS
    The GETRESOURCEALIAS function returns the resource alias value specified in a Resource Registry resource name file (.mrn).
  - GETRESOURCENAME
    The GETRESOURCENAME function returns the adapter source or target command of a specified card object. Without an argument, it returns the adapter command associated with the active source or destination.
  - GETTXINSTALLDIRECTORY
    The GETTXINSTALLDIRECTORY function returns the HCL Link product installation directory.
  - INDEX
    You can use the INDEX function when you need to select or test particular objects based on their occurrence, or to add a sequence number to output objects.
  - INDEXABS
    You can use INDEXABS when you need the absolute occurrence of a particular object across all occurrences, rather than across only valid occurrences.
  - LASTERRORCODE
    The LASTERRORCODE function returns a text item whose value is the last error code returned by one of a specified set of functions during map execution.
  - LASTERRORMSG
    The LASTERRORMSG function returns a text item whose value is the message corresponding to the last error code returned by one of a specified set of functions during map execution.
  - LOOKDOWN
    The LOOKDOWN function sequentially searches a series beginning at the end of the series, returning the last member of the series that meets a specified condition.
  - LOOKUP
    The LOOKUP function sequentially searches a series, returning the first member of the series that meets a specified condition.
  - MEMBER
    Use MEMBER when you need to know whether an object occurs within a series.
  - SEARCHDOWN
    Use the SEARCHDOWN function to look up data within a series of data that is sorted in descending code-page byte-order.
  - SEARCHUP
    Use the SEARCHUP function to look up data within a series of data that is sorted in ascending code-page byte-order.
  - SORTDOWN
    Use the SORTDOWN function to sort objects in a series in descending sequence.
  - SORTDOWNBY
    Use SORTDOWNBY to sort the objects of a series based on a component that the objects contain.
  - SORTUP
    Use SORTUP to sort the objects of a series in ascending sequence.
  - SORTUPBY
    Use SORTUPBY to sort the objects of a series based on a component that the objects contain.
  - UNIQUE
    The UNIQUE function returns a series containing all "unique" members of a series.
  - GETENV
    The GETENV function returns the value of the environment variable. If no variable exists, an empty string is returned.
  - GETOSNAME
    The GETOSNAME function returns the name of the operating system.
- Math and statistics functions
  Precede all MATHLIB functions with mathlib->
- Text functions
  These functions are used to convert the text item in a map rule.
- XML functions
  There are several XML functions that you can call from component rules and map rules to process input XML data.
- Custom functions
  From the Type Designer or Map Designer, you can create custom functions to call external libraries.
- Date and time format strings
  You can use the listed format strings for numbers, dates and times in functions such as the CURRENTDATETIME, FROMNUMBER, TONUMBER, FROMDATETIME, and TODATETIME.
- Number format strings
  You can create custom number formats by using the given format strings.
- RUN function return codes
  The RUN function return codes and messages might result when using the RUN function.
- Character set codes for CPACKAGE, CSERIESTOTEXT, and CTEXT
  The second argument of the CPACKAGE, CSERIESTOTEXT, and CTEXT functions specifies the character set of the output of the function. The value of the second argument (the character set of the object content), must be a valid character set code.

LOOKDOWN

The LOOKDOWN function sequentially searches a series beginning at the end of the series, returning the last member of the series that meets a specified condition.

Syntax:: LOOKDOWN (series-object-expression , single-condition-expression)
Meaning:: LOOKDOWN (series_to_search , condition_to_evaluate)
Returns:: A single object

LOOKDOWN returns the last member of series_to_search for which condition_to_evaluate evaluates to "true"; it returns "none" if no member of series_to_search meets the condition specified by condition_to_evaluate.

Examples

LOOKDOWN (Account#:Customer , Company Name:Customer = "ACME")
This example returns the Account# of Customer whose Company Name is ACME.
LOOKDOWN (Part#:Row:DBSelect , Model#:Row:DBSelect = ModelCode:Legacy & Serial#:Row:DBSelect > "123")
This example returns the Part# of DBSelect where the Model# in that row matches the ModelCode of Legacy and the Serial# is greater than 123.

Related functions

CHOOSE
EXTRACT
LOOKUP
Note: LOOKDOWN differs from LOOKUP in that LOOKDOWN returns the last member of series_to_search that meets the condition_to_evaluate, while LOOKUP returns the first member of series_to_search that meets the condition_to_evaluate.
SEARCHUP
SEARCHDOWN
The LOOKDOWN function performs a sequential search on an unsorted series, starting from the end of the series. The SEARCHUP and SEARCHDOWN functions perform a binary search on a series that is sorted in ascending or descending code-page byte-order. The SEARCHUP and SEARCHDOWN functions are efficient for performing multiple searches on a large series. The LOOKDOWN function can be more efficient for performing fewer searches. Note that LOOKDOWN returns a different instance from the one returned by SEARCHUP and SEARCHDOWN if multiple instances in the series match the condition.