Explicit Column Selection

NQL requires you to explicitly list the columns you want to select. Wildcard syntax (SELECT * and COUNT(*)) is not supported.

Why explicit columns are required

Cost transparency

NQL queries can have costs associated with them based on the data accessed. By requiring explicit column lists, you know exactly what data you’re requesting and can better predict query costs. Implicit column selection through * would obscure this.

Governance compliance

Narrative’s governance engine evaluates every query to determine what data can be accessed based on permissions and access rules. Explicit column lists allow the governance engine to make precise decisions about query eligibility. With wildcard syntax, the engine couldn’t determine ahead of time which columns would be accessed.

Query plan optimization

This is especially important for Rosetta Stone queries. When you query Rosetta Stone, NQL compiles your query into SQL that pulls from multiple underlying tables. Consider this query:

SELECT
  rs.email,
  rs.phone
FROM narrative.rosetta_stone rs

NQL compiles this into something like:

SELECT email, NULL AS phone FROM email_table
UNION ALL
SELECT NULL AS email, phone FROM phone_table

With explicit columns, the query planner knows exactly which tables to include in the union. Tables that don’t contain any of the requested columns can be pruned entirely. If wildcards were allowed, a query like SELECT * FROM narrative.rosetta_stone would need to include every column from every table in the Rosetta Stone catalog. This would create massive query plans with potentially hundreds of tables in the union, even when you only need a few fields.

Migration from SQL

If you’re coming from standard SQL, here’s how to adapt your queries:

Replace SELECT *

Instead of selecting all columns, list the specific columns you need:

-- Instead of this (not supported):
SELECT * FROM company_data."123"

-- Write this:
SELECT
  user_id,
  email,
  created_at
FROM company_data."123"

Replace COUNT(*)

For counting rows, use COUNT(1):

-- Instead of this (not supported):
SELECT COUNT(*) FROM company_data."123"

-- Write this:
SELECT COUNT(1) AS row_count FROM company_data."123"

When you specifically want to count non-null values in a column, use COUNT(column_name):

-- Count rows where email is not null
SELECT COUNT(email) AS emails_present FROM company_data."123"

Replace SELECT t1., t2.

In joins, enumerate the columns from each table:

-- Instead of this (not supported):
SELECT t1.*, t2.*
FROM company_data."123" t1
JOIN company_data."456" t2 ON t1.id = t2.id

-- Write this:
SELECT
  t1.user_id,
  t1.email,
  t2.order_id,
  t2.amount
FROM company_data."123" t1
JOIN company_data."456" t2 ON t1.id = t2.id

Benefits of explicit selection

While requiring explicit columns may seem like extra work, it provides several benefits:

Clearer intent: Your query documents exactly what data you need
Faster queries: Only requested columns are processed and transferred
Easier maintenance: Changes to the underlying schema won’t unexpectedly affect your query results
Better cost control: You pay only for the data you actually use

NQL vs SQL

Other differences between NQL and standard SQL

NQL Syntax

Complete query structure and grammar

Rosetta Stone

Understanding identity resolution across datasets

Query Optimization

Tips for writing efficient queries

Overview

Data Types

SQL Commands

Operators

Functions

General Reference

Why explicit columns are required

Cost transparency

Governance compliance

Query plan optimization

Migration from SQL

Replace SELECT *

Replace COUNT(*)

Replace SELECT t1., t2.

Benefits of explicit selection

NQL vs SQL

NQL Syntax

Rosetta Stone

Query Optimization

​Why explicit columns are required

​Cost transparency

​Governance compliance

​Query plan optimization

​Migration from SQL

​Replace SELECT *

​Replace COUNT(*)

​Replace SELECT t1., t2.

​Benefits of explicit selection

​Related content

NQL vs SQL

NQL Syntax

Rosetta Stone

Query Optimization

Why explicit columns are required

Cost transparency

Governance compliance

Query plan optimization

Migration from SQL

Replace SELECT *

Replace COUNT(*)

Replace SELECT t1., t2.

Benefits of explicit selection

Related content