Introduction

NoQL aims to combine the ease of use and wide understanding of SQL Syntax with the power and flexibility of the MongoDB document model and aggregation pipeline.

To achieve this, NoQL is a SQL to MongoDB interpreter that provides for standard SQL statements with some caveats.

Key Concepts

NoQL supports parsing of either MySQL or PostgreSQL syntax.

NoQL follows the MongoDB requirements for fields and values including:

• Case-sensitive field names
• Case-sensitive and type exact field values
• Fields name cannot contain . or start with $

Documents

NoQL supports the standard MongoDB query and aggregation notation for document navigation including:

• Dot notation for field traversal including arrays
• Operators for object and array field manipulation

Objects

NoQL provides a shortcut syntax to selecting fields from objects using a sub-select without a where clause. See Objects

Arrays

NoQL provides many methods for using arrays and functions by using a sub select with a where statement. See Arrays

Joins

NoQL currently supports complex inner and left outer joins with hints to simplify required output processing. See Joins

Aliasing

NoQL requires aliasing (AS) for functions and sub queries

Example AS usage

SELECT 
    ABS(-1) AS `absId` 
FROM 
    `customers`

Using AS on a table requires prefixing

Example AS usage with a table with prefixing

SELECT 
    c.* 
FROM 
    customers AS c

Always alias on JOIN statements

Indexing

Complex aggregation pipelines on large sets of data requires an understanding of how MongoDB is utilising indexes, especially on joins. We are working on an index suggestion tool to simplify this process.