All Qcodo Query method calls take in an optional set of QQ Clauses. QQ Clauses allow you alter the result set by performing the equivalents of most of your major SQL clauses, including JOIN, ORDER BY, GROUP BY and DISTINCT.

The following is the list of QQ Clause classes and what parameters they take:

• QQ::OrderBy(array/list of QQNodes)
• QQ::GroupBy(array/list of QQNodes)
• QQ::Count(QQNode, string)
• QQ::Minimum(QQNode, string)
• QQ::Maximum(QQNode, string)
• QQ::Average(QQNode, string)
• QQ::Expand(QQNode)
• QQ::ExpandAsArray(QQNode for an Association Table)
• QQ::LimitInfo(integer[, integer = 0])
• QQ::Distinct()

OrderBy and GroupBy follow the conventions of SQL ORDER BY and GROUP BY. It takes in a list of one or more QQ Column Nodes. This list could be a parameterized list and/or an array.

Specifically for OrderBy, to specify a QQ Node that you wish to order by in descending order, add a "false" after the QQ Node. So for example, QQ::OrderBy(QQN::Person()->LastName, false, QQN::Person()->FirstName) will do the SQL equivalent of "ORDER BY last_name DESC, first_name ASC".

Count, Minimum, Maximum and Average are aggregation-related clauses, and only work when GroupBy is specified. These methods take in an attribute name, which can then be restored using GetVirtualAttribute() on the object.

Expand and ExapndAsArray deals with Object Expansion / Early Binding. More on this can be seen in the "Early Binding of Related Objects" example.

LimitInfo will limit the result set. The first integer is the maximum number of rows you wish to limit the query to. The optional second integer is the offset (if any).

And finally, Distinct will cause the query to be called with SELECT DISTINCT.

All clauses must be wrapped around a single QQ::Clause() call, which takes in any number of clause classes for your query.