lookupValue

Lookupvalue, often written as two words lookup value, refers to the operation of retrieving the data associated with a given key from a data collection. It is a common task in databases, spreadsheets, and programming, enabling rapid access to related information without scanning the entire dataset. A lookup usually relies on a lookup structure such as a table, a dictionary, or a map that stores key–value pairs and supports efficient retrieval by the key. When a key is missing, the lookup can return a default value, raise an error, or indicate a missing result.

In spreadsheets, lookup functions implement this behavior. Common examples include VLOOKUP and HLOOKUP, which search a table for a key and return a value from a specified column or row. Most modern spreadsheet tools offer exact-match and approximate-match options, and newer functions may allow array results or multiple criteria.

In databases and programming languages, lookups are performed via joins, foreign keys, or maps. A lookup translated as a query or a map.get operation retrieves the value associated with the key. Performance depends on indexing, data structure, and size. Duplicate keys can complicate lookups and may require rules for choosing a single result or returning multiple matches.

Related concepts include lookup tables, index structures, and reference integrity. Best practices emphasize clear handling of missing keys, consistent data types, and predictable return values to minimize errors in downstream processing.