Friday, October 17, 2025

Making a Textual content to SQL App with OpenAI + FastAPI + SQLite


Making a Textual content to SQL App with OpenAI + FastAPI + SQLitePicture by Writer

 

Introduction

 
Information has turn out to be an indispensable useful resource for any profitable enterprise, because it supplies priceless insights for knowledgeable decision-making. Given the significance of knowledge, many firms are constructing techniques to retailer and analyze it. Nevertheless, there are numerous instances when it’s exhausting to amass and analyze the required information, particularly with the growing complexity of the information system.

With the appearance of generative AI, information work has turn out to be considerably simpler, as we will now use easy pure language to obtain largely correct output that carefully follows the enter we offer. It’s additionally relevant to information processing and evaluation with SQL, the place we will ask for question growth.

On this article, we’ll develop a easy API software that interprets pure language into SQL queries that our database understands. We’ll use three major instruments: OpenAI, FastAPI, and SQLite.

Right here’s the plan.

 

Textual content-to-SQL App Growth

 
First, we’ll put together the whole lot wanted for our venture. All you have to present is the OpenAI API key, which we’ll use to entry the generative mannequin. To containerize the appliance, we’ll use Docker, which you’ll purchase for the native implementation utilizing Docker Desktop.

Different elements, resembling SQLite, will already be out there once you set up Python, and FastAPI shall be put in later.

For the general venture construction, we’ll use the next:

text_to_sql_app/
├── app/
│   ├── __init__.py          
│   ├── database.py           
│   ├── openai_utils.py       
│   └── major.py               
├── demo.db                   
├── init_db.sql               
├── necessities.txt          
├── Dockerfile                
├── docker-compose.yml        
├── .env

 

Create the construction like above, or you should utilize the next repository to make issues simpler. We’ll nonetheless undergo every file to realize an understanding of the right way to develop the appliance.

Let’s begin by populating the .env file with the OpenAI API key we beforehand acquired. You are able to do that with the next code:

OPENAI_API_KEY=YOUR-API-KEY

 

Then, go to the necessities.txt to fill within the vital libraries we’ll use for

fastapi
uvicorn
sqlalchemy
openai
pydantic
python-dotenv

 

Subsequent, we transfer on to the __init__.py file, and we’ll put the next code inside:

from pathlib import Path
from dotenv import load_dotenv

load_dotenv(dotenv_path=Path(__file__).resolve().father or mother.father or mother / ".env", override=False)

 

The code above ensures that the atmosphere comprises all the required keys we’d like.

Then, we’ll develop Python code within the database.py file to hook up with the SQLite database we’ll create later (known asdemo.db) and supply a method to run SQL queries.

from sqlalchemy import create_engine, textual content
from sqlalchemy.orm import Session

ENGINE = create_engine("sqlite:///demo.db", future=True, echo=False)

def run_query(sql: str) -> listing[dict]:
    with Session(ENGINE) as session:
        rows = session.execute(textual content(sql)).mappings().all()
    return [dict(r) for r in rows]

 

After that, we’ll put together the openai_utils.py file that may settle for the database schema and the enter questions. The output shall be JSON containing the SQL question (with a guard to stop any write operations).

import os
import json
from openai import OpenAI        

shopper = OpenAI(api_key=os.getenv("OPENAI_API_KEY"))

_SYSTEM_PROMPT = """
You change natural-language questions into read-only SQLite SQL.
By no means output INSERT / UPDATE / DELETE.
Return JSON: { "sql": "..." }.
"""

def text_to_sql(query: str, schema: str) -> str:
    response = shopper.chat.completions.create(
        mannequin="gpt-4o-mini",        
        temperature=0.1,
        response_format={"sort": "json_object"},
        messages=[
            {"role": "system", "content": _SYSTEM_PROMPT},
            {"role": "user",
             "content": f"schema:n{schema}nnquestion: {question}"}
        ]
    )
    payload = json.masses(response.selections[0].message.content material)
    return payload["sql"]

 

With each the code and the connection prepared, we’ll put together the appliance utilizing FastAPI. The applying will settle for pure language questions and the database schema, convert them into SQL SELECT queries, run them by way of the SQLite database, and return the outcomes as JSON. The applying shall be an API we will entry by way of the CLI.

from fastapi import FastAPI, HTTPException
from pydantic import BaseModel
from sqlalchemy import examine
from .database import ENGINE, run_query
from .openai_utils import text_to_sql

app = FastAPI(title="Textual content-to-SQL Demo")

class NLRequest(BaseModel):
    query: str

@app.on_event("startup")
def capture_schema() -> None:
    insp = examine(ENGINE)
    international SCHEMA_STR
    SCHEMA_STR = "n".be a part of(
        f"CREATE TABLE {t} ({', '.be a part of(c['name'] for c in insp.get_columns(t))});"
        for t in insp.get_table_names()
    )

@app.put up("/question")
def question(req: NLRequest):
    attempt:
        sql = text_to_sql(req.query, SCHEMA_STR)
        if not sql.lstrip().decrease().startswith("choose"):
            elevate ValueError("Solely SELECT statements are allowed")
        return {"sql": sql, "end result": run_query(sql)}
    besides Exception as e:
        elevate HTTPException(status_code=400, element=str(e))

 

That’s the whole lot we’d like for the primary software. The subsequent factor we’ll put together is the database. Use the database under within the init_db.sql for instance functions, however you’ll be able to at all times change it if you need.


DROP TABLE IF EXISTS order_items;
DROP TABLE IF EXISTS orders;
DROP TABLE IF EXISTS funds;
DROP TABLE IF EXISTS merchandise;
DROP TABLE IF EXISTS prospects;

CREATE TABLE prospects (
    id INTEGER PRIMARY KEY,
    title TEXT NOT NULL,
    nation TEXT,
    signup_date DATE
);

CREATE TABLE merchandise (
    id INTEGER PRIMARY KEY,
    title TEXT NOT NULL,
    class TEXT,
    worth REAL
);

CREATE TABLE orders (
    id INTEGER PRIMARY KEY,
    customer_id INTEGER,
    order_date DATE,
    whole REAL,
    FOREIGN KEY (customer_id) REFERENCES prospects(id)
);

CREATE TABLE order_items (
    order_id INTEGER,
    product_id INTEGER,
    amount INTEGER,
    unit_price REAL,
    PRIMARY KEY (order_id, product_id),
    FOREIGN KEY (order_id) REFERENCES orders(id),
    FOREIGN KEY (product_id) REFERENCES merchandise(id)
);

CREATE TABLE funds (
    id INTEGER PRIMARY KEY,
    order_id INTEGER,
    payment_date DATE,
    quantity REAL,
    technique TEXT,
    FOREIGN KEY (order_id) REFERENCES orders(id)
);

INSERT INTO prospects (id, title, nation, signup_date) VALUES
 (1,'Alice','USA','2024-01-05'),
 (2,'Bob','UK','2024-03-10'),
 (3,'Choi','KR','2024-06-22'),
 (4,'Dara','ID','2025-01-15');

INSERT INTO merchandise (id, title, class, worth) VALUES
 (1,'Laptop computer Professional','Electronics',1500.00),
 (2,'Noise-Canceling Headphones','Electronics',300.00),
 (3,'Standing Desk','Furnishings',450.00),
 (4,'Ergonomic Chair','Furnishings',250.00),
 (5,'Monitor 27"','Electronics',350.00);

INSERT INTO orders (id, customer_id, order_date, whole) VALUES
 (1,1,'2025-02-01',1850.00),
 (2,2,'2025-02-03',600.00),
 (3,3,'2025-02-05',350.00),
 (4,1,'2025-02-07',450.00);

INSERT INTO order_items (order_id, product_id, amount, unit_price) VALUES
 (1,1,1,1500.00),
 (1,2,1,300.00),
 (1,5,1,350.00),
 (2,3,1,450.00),
 (2,4,1,250.00),
 (3,5,1,350.00),
 (4,3,1,450.00);

INSERT INTO funds (id, order_id, payment_date, quantity, technique) VALUES
 (1,1,'2025-02-01',1850.00,'Credit score Card'),
 (2,2,'2025-02-03',600.00,'PayPal'),
 (3,3,'2025-02-05',350.00,'Credit score Card'),
 (4,4,'2025-02-07',450.00,'Financial institution Switch');

 

Then, run the next code in your CLI to create a SQLite database for our venture.

sqlite3 demo.db < init_db.sql  

 

With the database prepared, we’ll create a Dockerfile to containerize our software.

FROM python:3.12-slim
WORKDIR /code

COPY necessities.txt .
RUN pip set up --no-cache-dir -r necessities.txt

COPY . .

CMD ["uvicorn", "app.main:app", "--host", "0.0.0.0", "--port", "8000"]

 

We may also create a docker-compose.yml file for operating the appliance extra easily.

providers:
  text2sql:
    construct: .
    env_file: .env    
    ports:
      - "8000:8000"    
    restart: unless-stopped
    volumes:
      - ./demo.db:/code/demo.db

 

With the whole lot prepared, begin your Docker Desktop and run the next code to construct the appliance.

docker compose construct --no-cache   
docker compose up -d 

 

If the whole lot is finished properly, you’ll be able to check the appliance by utilizing the next code. We’ll ask what number of prospects we now have within the information.

curl -X POST "http://localhost:8000/question" -H "Content material-Sort: software/json" -d "{"query":"What number of prospects?"}"

 

The output will appear to be this.

{"sql":"SELECT COUNT(*) AS customer_count FROM prospects;","end result":[{"customer_count":4}]}

 

We will attempt one thing extra advanced, just like the variety of orders for every buyer:

curl -X POST "http://localhost:8000/question" -H "Content material-Sort: software/json" -d "{"query":"What's the variety of orders positioned by every buyer"}"

 

With output like under.

{"sql":"SELECT customer_id, COUNT(*) AS number_of_orders FROM orders GROUP BY customer_id;","end result":[{"customer_id":1,"number_of_orders":2},{"customer_id":2,"number_of_orders":1},{"customer_id":3,"number_of_orders":1}]}

 

That’s all you have to construct a fundamental Textual content-to-SQL software. You possibly can improve it additional with a front-end interface and a extra advanced system tailor-made to your wants.

 

Wrapping Up

 
Information is the guts of any information work, and corporations use it to make selections. Many instances, the system we now have is just too advanced, and we have to depend on generative AI to assist us navigate it.

On this article, we now have realized the right way to develop a easy Textual content-to-SQL software utilizing the OpenAI mannequin, FastAPI, and SQLite.

I hope this has helped!
 
 

Cornellius Yudha Wijaya is an information science assistant supervisor and information author. Whereas working full-time at Allianz Indonesia, he likes to share Python and information suggestions by way of social media and writing media. Cornellius writes on a wide range of AI and machine studying matters.

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