query GetUser($id: ID!) {
  user(id: $id) {
    id
    name
    email
  }
}

mutation CreatePost($input: CreatePostInput!) {
  createPost(input: $input) {
    id
    title
    createdAt
  }
}

subscription OnMessageReceived($channelId: ID!) {
  messageReceived(channelId: $channelId) {
    id
    content
    sender {
      id
      name
    }
  }
}

# Required variable
query GetUser($id: ID!) { ... }

# Optional variable with default
query ListPosts($first: Int = 20) { ... }

# Multiple variables
query SearchPosts($query: String!, $status: PostStatus, $first: Int = 10) { ... }

# Define fragment
fragment UserBasicInfo on User {
  id
  name
  avatarUrl
}

# Use fragment
query GetUser($id: ID!) {
  user(id: $id) {
    ...UserBasicInfo
    email
  }
}

query GetUser($id: ID!, $includeEmail: Boolean!) {
  user(id: $id) {
    id
    name
    email @include(if: $includeEmail)
  }
}

query GetPosts($skipDrafts: Boolean!) {
  posts {
    id
    title
    draft @skip(if: $skipDrafts)
  }
}

# Good: Specific fields
query GetUserName($id: ID!) {
  user(id: $id) {
    id
    name
  }
}

# Avoid: Over-fetching
query GetUser($id: ID!) {
  user(id: $id) {
    id
    name
    email
    bio
    posts {
      id
      title
      content
      comments {
        id
      }
    }
    followers {
      id
      name
    }
    # ... many unused fields
  }
}

# Good: Named operation
query GetUserPosts($userId: ID!) {
  user(id: $userId) {
    posts {
      id
      title
    }
  }
}

# Avoid: Anonymous operation
query {
  user(id: "123") {
    posts {
      id
      title
    }
  }
}

# Good: Variables
query GetUser($id: ID!) {
  user(id: $id) {
    id
    name
  }
}

# Avoid: Hardcoded values
query {
  user(id: "123") {
    id
    name
  }
}

// UserAvatar.tsx
export const USER_AVATAR_FRAGMENT = gql`
  fragment UserAvatar on User {
    id
    name
    avatarUrl
  }
`;

function UserAvatar({ user }) {
  return <img src={user.avatarUrl} alt={user.name} />;
}