SQL To JSON - Complete Guide

SQL to JSON converter transforms SQL query results or CREATE TABLE statements into JSON format. Essential for API development, data migration, database documentation, and bridging relational databases with NoSQL or JavaScript applications.

How It Works

For query results: each row becomes a JSON object with column names as keys. For CREATE TABLE: extracts table name, columns, types, and constraints into structured JSON. Handles NULL values, data types, and nested structures appropriately.

Technical Details

SQL types map to JSON: VARCHAR/TEXT → string, INT/BIGINT → number, BOOLEAN → true/false, NULL → null, DATE/TIMESTAMP → ISO string. Arrays and JSON columns may need special handling. Preserves column order from SELECT or table definition.

Common Use Cases

1. API Response Generation: Convert database results to JSON for REST APIs.
2. Database Documentation: Export schema as JSON for documentation tools.
3. Data Migration: Convert relational data to document format for NoSQL.
4. Test Data Creation: Generate JSON fixtures from SQL queries.

Code Examples

SQL Results to JSON

// Database query result to JSON
function sqlResultToJSON(columns, rows) {
  return rows.map(row => {
    const obj = {};
    columns.forEach((col, i) => {
      obj[col.name] = row[i];
    });
    return obj;
  });
}

// Example usage
const columns = [{name: 'id'}, {name: 'name'}, {name: 'email'}];
const rows = [
  [1, 'John', 'john@example.com'],
  [2, 'Jane', 'jane@example.com']
];

JSON.stringify(sqlResultToJSON(columns, rows), null, 2);
// [
//   {"id": 1, "name": "John", "email": "john@example.com"},
//   {"id": 2, "name": "Jane", "email": "jane@example.com"}
// ]

Map each row to an object using column names as keys. Handle nulls and type conversion as needed.

Tips & Best Practices

• Use ISO 8601 for dates
• Handle NULL consistently
• Consider JSON Lines for large data
• Preserve column order if important
• Validate JSON output schema

Common Mistakes to Avoid

• Losing NULL vs empty string distinction
• Timezone issues with dates
• Memory issues with large datasets
• Not handling special characters in strings

When to Use This Tool

Use SQL to JSON when building APIs that query databases, migrating data to document stores, generating test fixtures, or creating database documentation.

Frequently Asked Questions

How are SQL NULL values handled?

NULL becomes JSON null. Some converters offer options: omit null fields, use empty string, or use a sentinel value. JSON null is usually the correct choice for data integrity.

What about SQL dates and times?

Typically converted to ISO 8601 strings (2024-01-15T10:30:00Z). Some tools offer Unix timestamp or custom format options. Ensure consistent timezone handling.

Can I convert JOINed results?

Yes, but flattened. For nested JSON from JOINs, you need multiple queries or database-specific JSON functions (JSON_AGG in PostgreSQL, JSON_ARRAYAGG in MySQL).

How do I handle large result sets?

Stream conversion for large datasets. Convert row-by-row rather than loading all into memory. Output as JSON Lines (one object per line) for processing.

Get Started

Ready to try SQL To JSON? Use the tool now - it's free, fast, and works right in your browser.

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Last updated: June 27, 2026