# Mapping functions

This section describes functions for handling mapping tables. A mapping table can be used to replace field values or field names during script execution.

Mapping functions can only be used in the data load script

Use the drop-down on each function to see a brief description and the syntax of each function. Click the function name in the syntax description for further details.

[](https://help.qlik.com/en-US/sense/Subsystems/Hub/Content/Sense_Hub/Scripting/MappingFunctions/mapping-functions.htm)

#### ApplyMap

The ApplyMap script function is used for mapping the output of an expression to a previously loaded mapping table.

[**ApplyMap**](https://help.qlik.com/en-US/sense/May2026/Subsystems/Hub/Content/Sense_Hub/Scripting/MappingFunctions/ApplyMap.htm)('mapname', expr [ , defaultexpr ] )

[](https://help.qlik.com/en-US/sense/Subsystems/Hub/Content/Sense_Hub/Scripting/MappingFunctions/mapping-functions.htm)

#### MapSubstring

The MapSubstring script function is used to map parts of any expression to a previously loaded mapping table. The mapping is case sensitive and non-iterative, and substrings are mapped from left to right.

[**MapSubstring**](https://help.qlik.com/en-US/sense/May2026/Subsystems/Hub/Content/Sense_Hub/Scripting/MappingFunctions/MapSubstring.htm)('mapname', expr)