gh-djankies-claude-configs-prisma-6/skills/optimizing-query-performance/references/field-selection.md

Field Selection Guide

Select vs Include

select: Choose specific fields (excludes all others)

const user = await prisma.user.findUnique({
  where: { id: 1 },
  select: {
    id: true,
    email: true
  }
})

include: Add relations to default fields

const user = await prisma.user.findUnique({
  where: { id: 1 },
  include: {
    orders: true
  }
})

Cannot use both select and include in same query.

Nested Selection

const users = await prisma.user.findMany({
  select: {
    id: true,
    email: true,
    orders: {
      select: {
        id: true,
        total: true,
        createdAt: true
      },
      where: { status: 'completed' },
      orderBy: { createdAt: 'desc' },
      take: 5
    }
  }
})

Only fetches recent completed orders, not all orders.

Counting Relations Without Loading

const users = await prisma.user.findMany({
  select: {
    id: true,
    email: true,
    _count: {
      select: {
        orders: true,
        posts: true
      }
    }
  }
})

Returns counts without loading actual relation records.