# Class: ColumnReferenceCollector

Defined in: packages/core/src/transformers/ColumnReferenceCollector.ts:78

A comprehensive collector for all ColumnReference instances in SQL query structures.

This collector extends beyond the capabilities of SelectableColumnCollector by traversing CTE internal queries, subqueries, and all nested SQL components to collect every column reference instance in the query tree. It's specifically designed for transformation scenarios where all column references need to be identified and potentially modified.

Key Differences from SelectableColumnCollector

Feature	SelectableColumnCollector	ColumnReferenceCollector
CTE Internal Scanning	❌ Skipped	✅ Included
Subquery Traversal	❌ Limited	✅ Comprehensive
Deduplication	✅ Yes	❌ No (preserves all instances)
Use Case	Column selection analysis	Column reference transformation

Supported Query Types

• SimpleSelectQuery: Standard SELECT statements with all clauses
• BinarySelectQuery: UNION, INTERSECT, EXCEPT operations
• Nested CTEs: WITH clauses and their internal queries
• Subqueries: All subquery types in FROM, WHERE, SELECT clauses
• Complex Expressions: CASE, functions, binary operations, etc.

Examples

import { ColumnReferenceCollector, SelectQueryParser } from 'rawsql-ts';

const sql = `
  WITH user_data AS (
    SELECT id, name FROM users WHERE status = 'active'
  ),
  order_summary AS (
    SELECT user_data.id, COUNT(*) as order_count
    FROM user_data
    JOIN orders ON user_data.id = orders.user_id
    GROUP BY user_data.id
  )
  SELECT * FROM order_summary
`;

const query = SelectQueryParser.parse(sql);
const collector = new ColumnReferenceCollector();
const columnRefs = collector.collect(query);

console.log(`Found ${columnRefs.length} column references:`);
columnRefs.forEach(ref => {
  const tableName = ref.namespaces?.[0]?.name || 'NO_TABLE';
  console.log(`- ${tableName}.${ref.column.name}`);
});

// Output includes references from:
// - CTE definitions: users.id, users.name, users.status
// - Main query: user_data.id, orders.user_id, etc.

// Use for column reference transformation
const columnRefs = collector.collect(query);

// Update all references to 'old_table' to 'new_table'
columnRefs.forEach(ref => {
  if (ref.namespaces?.[0]?.name === 'old_table') {
    ref.namespaces[0].name = 'new_table';
  }
});

Since

0.11.16

Implements

• SqlComponentVisitor<void&gt;

Constructors

Constructor

new ColumnReferenceCollector(): ColumnReferenceCollector

Defined in: packages/core/src/transformers/ColumnReferenceCollector.ts:83

Returns

ColumnReferenceCollector

Methods

collect()

collect(query): ColumnReference[]

Defined in: packages/core/src/transformers/ColumnReferenceCollector.ts:171

Collects all ColumnReference instances from the given SQL query component.

This method performs a comprehensive traversal of the entire query structure, including CTE definitions, subqueries, and all expression types to collect every ColumnReference instance. The returned references are actual instances from the query tree, allowing for direct modification.

Parameters

query

SqlComponent

The SQL query component to analyze. Can be SimpleSelectQuery, BinarySelectQuery, or any SqlComponent.

Returns

ColumnReference[]

An array of all ColumnReference instances found in the query. Each reference maintains its original object identity for modification purposes.

Examples

const collector = new ColumnReferenceCollector();
const columnRefs = collector.collect(query);

// Analyze collected references
`const tableReferences = new Map<string, number>();`
columnRefs.forEach(ref => {
  const tableName = ref.namespaces?.[0]?.name || 'unqualified';
  tableReferences.set(tableName, (tableReferences.get(tableName) || 0) + 1);
});

console.log('Table reference counts:', tableReferences);

// Transform references during collection
const columnRefs = collector.collect(query);

// Replace all references to 'old_schema.table' with 'new_schema.table'
columnRefs.forEach(ref => {
  if (ref.namespaces?.length === 2 && 
      ref.namespaces[0].name === 'old_schema' && 
      ref.namespaces[1].name === 'table') {
    ref.namespaces[0].name = 'new_schema';
  }
});

Since

0.11.16

---

visit()

visit(component): void

Defined in: packages/core/src/transformers/ColumnReferenceCollector.ts:275

Parameters

component

SqlComponent

Returns

void

Implementation of

SqlComponentVisitor.visit