Which function is essential for querying data in Appian?

The function that is essential for querying data in Appian is queryEntities(). This function is specifically designed to retrieve multiple records from a data source by allowing users to specify query filters and controls, making it highly versatile for obtaining sets of related data.

Using queryEntities(), developers can leverage various parameters to shape their queries, including selecting specific fields, applying filters, sorting results, and paginating through large data sets. It provides a powerful mechanism to interact with the underlying data models in Appian while ensuring that only relevant data is retrieved based on the defined criteria.

While the other options relate to data retrieval, they are more specialized. For instance, getData() primarily fetches single records or specific data points, while getRecord() is often related to accessing individual records based on a defined type. FetchData() does not exist as a standard function in Appian's query language, highlighting that queryEntities() remains the fundamental choice for querying data effectively across various contexts.