Mirror of <https://developer.salesforce.com/docs/data/data-cloud-query-guide/references/dc-sql-reference/lambda-expressions.html> (Salesforce, Data 360 Query Guide), read 2026-10-23. Salesforce's own page is the authority; this copy exists because that site refuses non-browser readers.

Lambda Expressions

Applies to: ✅ Data 360 SQL ✅ Tableau Hyper API

Lambda expressions are anonymous functions you pass as arguments to higher-order functions such as ARRAY_TRANSFORM and ARRAY_FILTER. They enable element-wise operations on arrays without writing separate function definitions.

<param1>, <param2>, ...: One or more parameter names that represent the elements from the input arrays. The number of parameters must match the number of array arguments passed to the function.
<expression>: Any valid SQL expression that uses the parameters. The expression is evaluated once for each element (or tuple of elements) in the input arrays.

Lambda expressions can only be used as arguments to functions that accept them, such as ARRAY_TRANSFORM and ARRAY_FILTER.
The parameter names are local to the lambda and don’t conflict with column names in the outer query.
Lambda expressions can’t reference columns or variables from the outer query scope.
The return type of the lambda expression is inferred from the expression. If the expression returns only NULL, you must cast it to a specific type.
Data 360 uses the Python / DuckDB-style lambda syntax (lambda x: expr), not the Spark / Snowflake-style arrow syntax (x -> expr).

Use a single parameter when operating on one array.

Returns [2, 4, 6].

Use multiple parameters when operating on multiple arrays in parallel.

Returns [11, 22, 33].

Use CASE expressions within lambdas for conditional transformations.

Returns [4, 5, 6].

Return a boolean expression to filter array elements.

Returns [2, 4, 6].

Lambdas work with any data type.

Returns ["HELLO!", "WORLD?"].