---
title: "Query CSV"
url: "https://help.flows.world/en/article/query-csv"
language: "en"
last_updated: "2025-12-16T19:17:54.718Z"
---

# Query CSV

AWS S3 Only: This flow uses S3 Select and only works with AWS S3 (or S3-compatible storage that supports S3 Select). It will NOT work with DigitalOcean Spaces or other providers that do not support S3 Select.

Query CSV allows you to run SQL-like queries directly on CSV files stored in S3. Instead of downloading the entire file, S3 filters the data and returns only matching rows.

**Parameters**

| **Parameter** | **Required** | **Description** |
| --- | --- | --- |
| key | Yes | The path/filename of the CSV file to query (e.g., "reports/sales.csv") |
| query | Yes | SQL query to execute (e.g., "SELECT \* FROM s3object WHERE status='active'") |

**Example Payload**

{  
    "key": "reports/users.csv",  
    "query": "SELECT \* FROM s3object WHERE status='active'"  
}

**SQL Query Examples**

| **Query** | **Description** |
| --- | --- |
| SELECT \* FROM s3object | Returns all rows |
| SELECT \* FROM s3object WHERE status='active' | Returns only rows where status is "active" |
| SELECT name, email FROM s3object | Returns only the name and email columns |
| SELECT \* FROM s3object WHERE id='2' | Returns the row with id 2 |
| SELECT \* FROM s3object LIMIT 10 | Returns only the first 10 rows |

**Response**

On success, returns:

-   data - The filtered CSV content (only matching rows)
-   data.responseCode - HTTP status code (200 for success)

On error, returns:

-   error - Error details from S3
-   error.responseCode - HTTP error code
-   error.Message - Error description

**How It Works**

Query CSV uses S3 Select, a feature that allows you to retrieve a subset of data from an object using SQL expressions. This is more efficient than downloading entire files when you only need specific data.

-   The flow sends a POST request to S3 with your SQL query in an XML payload
-   S3 parses the CSV file and executes the query server-side
-   Only matching rows are returned, reducing data transfer and processing time
-   The first row of your CSV must contain column headers (these become field names in queries)

**Supported SQL Syntax**

-   SELECT - Specify columns (\* for all, or comma-separated column names)
-   FROM s3object - Always use "s3object" as the table name
-   WHERE - Filter rows using conditions (=, <>, <, >, <=, >=, AND, OR, NOT)
-   LIMIT - Restrict the number of returned rows