Connection Strings
From Scratch

# Relative path
sqlite:///relative/path/to/db.sqlite

# Absolute path (note 4 slashes on Unix)
sqlite:////home/user/mydb.sqlite

# In-memory (lost when connection closes)
sqlite:///:memory:

# Python built-in
import sqlite3
conn = sqlite3.connect("mydb.sqlite")
conn = sqlite3.connect(":memory:")

// JDBC URL
jdbc:oracle:thin:@hostname:1521:ORCL
// With service name (preferred in modern Oracle)
jdbc:oracle:thin:@//hostname:1521/service_name

# Python (cx_Oracle / python-oracledb)
DSN = "hostname:1521/service_name"
conn = cx_Oracle.connect(
    user="scott", password="tiger", dsn=DSN
)
# SQLAlchemy
"oracle+cx_oracle://user:pass@host:1521/?service_name=orcl"

# Supabase direct connection
postgresql://postgres:[password]@
db.xxxx.supabase.co:5432/postgres

# Supabase pooled (transaction mode via PgBouncer)
postgresql://postgres:[password]@
aws-0-us-east-1.pooler.supabase.com:6543/postgres

# Neon (serverless Postgres)
postgresql://user:pass@ep-xxx.us-east-2.aws.neon.tech/dbname
?sslmode=require

# PlanetScale (MySQL-compatible)
mysql://user:pass@xxx.connect.psdb.cloud/mydb
?ssl={"rejectUnauthorized":true}

# NoSQL API (native SDK)
from azure.cosmos import CosmosClient
client = CosmosClient(
    url="https://myaccount.documents.azure.com:443/",
    credential="PRIMARY_KEY_HERE"
)

# MongoDB API (use mongo URI with SSL)
mongodb://account:PRIMARY_KEY@
account.mongo.cosmos.azure.com:10255/mydb
?ssl=true&retrywrites=false

# Connection string from portal
AccountEndpoint=https://account.documents.azure.com:443/;
AccountKey=BASE64KEY==;

// Client SDK (browser/React Native)
import { initializeApp } from "firebase/app";
const firebaseConfig = {
  apiKey: "AIzaSy...",
  authDomain: "myapp.firebaseapp.com",
  projectId: "myapp-12345",
  storageBucket: "myapp.appspot.com",
  messagingSenderId: "123456789",
  appId: "1:123:web:abc..."
};
const app = initializeApp(firebaseConfig);

# Python Admin SDK (server-side)
import firebase_admin
cred = firebase_admin.credentials.Certificate(
    "serviceAccountKey.json"
)
firebase_admin.initialize_app(cred)

# Python (boto3)
import boto3
dynamodb = boto3.resource(
    "dynamodb",
    region_name="us-east-1",
    aws_access_key_id="AKIAIOSFODNN7",
    aws_secret_access_key="wJalrXUtnFEMI"
)
# Or use environment variables (preferred)
# AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY, AWS_DEFAULT_REGION

# Local DynamoDB for dev
dynamodb = boto3.resource(
    "dynamodb",
    endpoint_url="http://localhost:8000"
)

import chromadb

# In-memory (ephemeral — for testing)
client = chromadb.EphemeralClient()

# Persistent local (file-backed)
client = chromadb.PersistentClient(
    path="/path/to/chroma_data"
)

# Remote HTTP client (ChromaDB server running)
client = chromadb.HttpClient(
    host="localhost",
    port=8000
)

# Cloud (Chroma Cloud)
client = chromadb.cloud.CloudClient(
    tenant="my-tenant",
    database="my-db",
    api_key="chroma-api-key"
)

from pinecone import Pinecone

# Initialize with API key
pc = Pinecone(api_key="your-api-key")

# Connect to index
index = pc.Index("my-index")

# Or specify host directly
index = pc.Index(
    name="my-index",
    host="https://my-index-xxx.svc.pinecone.io"
)

import weaviate
from weaviate.auth import AuthApiKey

# Local instance
client = weaviate.connect_to_local(
    host="localhost",
    port=8080, grpc_port=50051
)

# Weaviate Cloud Services (WCS)
client = weaviate.connect_to_wcs(
    cluster_url="https://cluster.weaviate.network",
    auth_credentials=AuthApiKey("wcs-api-key")
)

from neo4j import GraphDatabase

# Bolt protocol (default, binary, fast)
driver = GraphDatabase.driver(
    "bolt://localhost:7687",
    auth=("neo4j", "password")
)

# Neo4j Aura (cloud, TLS)
driver = GraphDatabase.driver(
    "neo4j+s://xxxxx.databases.neo4j.io",
    auth=("neo4j", "password")
)
# neo4j:// — bolt, no TLS
# neo4j+s:// — bolt with TLS
# neo4j+ssc:// — bolt with TLS, no cert validation