where() public method Sets the WHERE part of the query

leftJoin() public method Appends a LEFT OUTER JOIN part

one() public method Executes the query and returns a single

queryScalar() protected method Queries a scalar value

orWhere() public method Adds an additional WHERE condition

$union public property This is used to construct the UNION clause(s)

orHaving() public method Adds an additional HAVING condition

addSelect() public method Add more columns to the SELECT

create() public static method Creates a new Query object

addGroupBy() public method Adds additional group-by columns