druid/docs/querying/sql-multivalue-string-functions.md

---
id: sql-multivalue-string-functions
title: "SQL multi-value string functions"
sidebar_label: "Multi-value string functions"
---

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> Apache Druid supports two query languages: Druid SQL and [native queries](querying.md).
> This document describes the SQL language.

Druid supports string dimensions containing multiple values.
This page describes the operations you can perform on multi-value string dimensions using [Druid SQL](./sql.md).
See [Multi-value dimensions](multi-value-dimensions.md) for more information.

All "array" references in the multi-value string function documentation can refer to multi-value string columns or
`ARRAY` literals.

|Function|Notes|
|--------|-----|
|`ARRAY[expr1, expr2, ...]`|Constructs a SQL ARRAY literal from the expression arguments, using the type of the first argument as the output array type.|
|`MV_FILTER_ONLY(expr, arr)`|Filters multi-value `expr` to include only values contained in array `arr`.|
|`MV_FILTER_NONE(expr, arr)`|Filters multi-value `expr` to include no values contained in array `arr`.|
|`MV_LENGTH(arr)`|Returns length of array expression.|
|`MV_OFFSET(arr, long)`|Returns the array element at the 0 based index supplied, or null for an out of range index.|
|`MV_ORDINAL(arr, long)`|Returns the array element at the 1 based index supplied, or null for an out of range index.|
|`MV_CONTAINS(arr, expr)`|Returns 1 if the array contains the element specified by `expr`, or contains all elements specified by `expr` if `expr` is an array, else 0.|
|`MV_OVERLAP(arr1, arr2)`|Returns 1 if arr1 and arr2 have any elements in common, else 0.|
|`MV_OFFSET_OF(arr, expr)`|Returns the 0 based index of the first occurrence of `expr` in the array, or `-1` or `null` if `druid.generic.useDefaultValueForNull=false` if no matching elements exist in the array.|
|`MV_ORDINAL_OF(arr, expr)`|Returns the 1 based index of the first occurrence of `expr` in the array, or `-1` or `null` if `druid.generic.useDefaultValueForNull=false` if no matching elements exist in the array.|
|`MV_PREPEND(expr, arr)`|Adds `expr` to `arr` at the beginning, the resulting array type determined by the type of the array.|
|`MV_APPEND(arr1, expr)`|Appends `expr` to `arr`, the resulting array type determined by the type of the first array.|
|`MV_CONCAT(arr1, arr2)`|Concatenates 2 arrays, the resulting array type determined by the type of the first array.|
|`MV_SLICE(arr, start, end)`|Returns the subarray of `arr` from the 0 based index start(inclusive) to end(exclusive), or `null`, if start is less than 0, greater than length of arr or less than end.|
|`MV_TO_STRING(arr, str)`|Joins all elements of `arr` by the delimiter specified by `str`.|
|`STRING_TO_MV(str1, str2)`|Splits `str1` into an array on the delimiter specified by `str2`.|