Supabase JS SDK and RLS SQL Cheat Sheet

This quick reference guide summarizes the most common patterns and configurations in Supabase.

1. JS SDK Database Queries Cheat Sheet

// 1. Fetching rows with filtering
const { data } = await supabase
  .from("items")
  .select("id, name")
  .eq("status", "active")
  .gt("price", 50);

// 2. Inserting record rows
await supabase
  .from("items")
  .insert([{ name: "New Item", price: 99.99 }]);

// 3. Updating record rows
await supabase
  .from("items")
  .update({ price: 79.99 })
  .eq("id", 12);

// 4. Deleting record rows
await supabase
  .from("items")
  .delete()
  .eq("id", 12);

2. Authentication SDK Helpers

// A. Registering with email
await supabase.auth.signUp({
  email: "user@example.com",
  password: "securepassword",
});

// B. Logging in with email
await supabase.auth.signInWithPassword({
  email: "user@example.com",
  password: "securepassword",
});

// C. Fetching active user session
const { data: { user } } = await supabase.auth.getUser();

// D. Logging out
await supabase.auth.signOut();

3. PostgreSQL RLS Policies Templates

-- Enable RLS on a table
ALTER TABLE posts ENABLE ROW LEVEL SECURITY;

-- Policy 1: Grant public read-only access (SELECT)
CREATE POLICY "Allow public read"
ON posts FOR SELECT
USING (true);

-- Policy 2: Restrict modifications to record owners (INSERT/UPDATE/DELETE)
CREATE POLICY "Allow owners write access"
ON posts FOR ALL
TO authenticated
USING (auth.uid() = author_id)
WITH CHECK (auth.uid() = author_id);