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Query PostgreSQL Database with Natural Language using GPT-4o-mini

by Babish ShresthaUpdated: Last update a month agoSource: n8n.io
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Getting Started

This Database SQL Query Agent convert natural language into sql query to get results

Turn your PostgreSQL database into a conversational AI agent! Ask questions in plain English and get instant data results without writing SQL.

✨ What It Does

  • Natural Language Queries : "Show laptops under $500 in stock" → Automatic SQL generation
  • Smart Column Mapping : Understands your terms and maps them to actual database columns
  • Conversational Memory : Maintains context across multiple questions
  • Universal Compatibility : Works with any PostgreSQL table structure

🎯 Perfect For

  • Business analysts querying data without SQL knowledge
  • Customer support finding information quickly
  • Product managers analyzing inventory/sales data
  • Anyone who needs database insights fast

🚀 Quick Setup

Step 1: Prerequisites

  • n8n instance (cloud/self-hosted)
  • PostgreSQL database with read access
  • OpenAI API key/You can use other LLM as well

Step 2: Import & Configure

  1. Import this workflow template into n8n
  2. Add Credentials :
    • OpenAI API: Add your API key
    • PostgreSQL: Configure database connection
  3. Set Table Name : Edit "Set Table Name" node → Replace "table_name" with your actual table
  4. Test Connection : Ensure your database user has SELECT permissions

Step 3: Deploy & Use

  1. Start the workflow
  2. Open the chat interface
  3. Ask questions like:
    • "Show all active users"
    • "Find orders from last month over $100"
    • "List products with low inventory"

🔧 Configuration Details

Required Settings

  • Table Name : Update in "Set Table Name" node
  • Database Schema : Default is 'public' (modify SQL if different)
  • Result Limit : Default 50 rows (adjustable in system prompt)

Optional Customizations

  • Multi-table Support : Modify system prompt and add table selection logic
  • Custom Filters : Add business rules to restrict data access
  • Output Format : Customize response formatting in the agent prompt

💡 Example Queries

E-commerce

"Show me all electronics under $200 that are in stock"

HR Database

"List employees hired in 2024 with salary over 70k"

Customer Data

"Find VIP customers from California with recent orders"

🛡️ Security Features

  • Read-only Operations : Only SELECT queries allowed
  • SQL Injection Prevention : Parameterized queries and validation
  • Result Limits : Prevents overwhelming queries
  • Safe Schema Discovery : Uses information_schema tables

🔍 How It Works

  1. Schema Discovery : Agent fetches table structure and column info
  2. Query Planning : Maps natural language to database columns
  3. SQL Generation : Creates safe, optimized queries
  4. Result Formatting : Returns clean, user-friendly data

⚡ Quick Troubleshooting

  • No Results : Check table name and ensure data exists
  • Permission Error : Verify database user has SELECT access
  • Connection Failed : Confirm PostgreSQL credentials and network access
  • Unexpected Results : Try more specific queries with exact column names

🎨 Use Cases

  • Inventory Management : "Show low-stock items by category"
  • Sales Analysis : "Top 10 products by revenue this quarter"
  • Customer Support : "Find customer orders with status 'pending'"
  • Data Exploration : "What are the unique product categories?"

🔧 Advanced Tips

  • Performance : Add database indexes on frequently queried columns
  • Customization : Modify the system prompt for domain-specific terminology
  • Scaling : Use read replicas for high-query volumes
  • Integration : Connect to Slack/Teams for team-wide data access

Tags : AI, PostgreSQL, Natural Language, SQL, Business Intelligence, LangChain, Database Query

Difficulty : Beginner to Intermediate
Setup Time : 10-15 minutes