SQL++ for Query Reference

  • reference
    This reference guide describes the syntax and structure of SQL++ for Query. It provides information about the basic elements which can be combined to build SQL++ statements. The Couchbase implementation of SQL++ was formerly known as N1QL.

    The SQL++ language is composed of statements, expressions, and comments.


    SQL++ statements are categorized into the following groups:


    The following are the different types of SQL++ expressions:

    Nested Path Expressions

    In SQL++, nested paths indicate an expression to access nested sub-documents within a JSON document or expression.

    For example, in the document below, the latitude of an airport is stored within the geo sub-document, and can be addressed using the nested path geo.lat:

        "airportname": "Calais Dunkerque",
        "city": "Calais",
        "geo": {
          "alt": 12,
          "lat": 50.962097,
          "lon": 1.954764
        "latitude": 51,
        // ...

    You can use nested operators to access sub-document fields within a document.


    SQL++ supports block comments and line comments.

    Block Comments

    block-comment ::= '/*' ( text | newline )* '*/'
    Syntax diagram

    A block comment starts with /* and ends with */. The query engine ignores the start and end markers /* */, and any text between them.

    A block comment may start on a new line, or in the middle of a line after other SQL++ statements. A block comment may contain line breaks.

    There may also be further SQL++ statements on the same line after the end of a block comment — the query engine does not ignore these.

    Line Comments

    line-comment ::=  '--' text?
    Syntax diagram

    You can use line comments in Couchbase Capella. A line comment starts with two hyphens --. The query engine ignores the two hyphens, and any text following them up to the end of the line.

    A line comment may start on a new line, or in the middle of a line after other SQL++ statements. A line comment may not contain line breaks.

    Optimizer Hints

    In Couchbase Capella you can supply hints to the optimizer within a specially-formatted hint comment. For further details, refer to Optimizer Hints.