> ## Documentation Index
> Fetch the complete documentation index at: https://www.integrate.io/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# ETL: MapToQueryString

> Convert a key-value map into a URL query string format (key1=value1&key2=value2). Use for building URL parameters in Integrate.io ETL pipelines.

## Description

Converts a map to a URL query string (key1=value1\&key2=value2)

## Syntax

`MapToQueryString(map_expression)`

## Arguments

*map\_expression* (map) - The map to convert to a query string.

## Examples

`MapToQueryString(TOMAP('k1','v1','k2','v2'))`returns k1=v1\&k2=v2

## Return value datatype

The function returns a string

## Impact of null value

If the map\_expression is null, null is returned.