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=== Where Queries
Where queries are the preferred way to build more complex queries. They are type safe, expressive and lazily executed:

[source,groovy]
----
def query = Book.where {
    title == 'The Stand'
}
----

Note that no query is actually executed directly, instead the `where(Closure)` method returns an instance of link:../api/grails/gorm/rx/DetachedCriteria.html[DetachedCriteria].

Like an `rx.Observable`, the `DetachedCriteria` class can be subscribed to:


[source,groovy]
----
Book.where {
    title == 'The Stand'
}
.subscribe { Book book ->
    println "Title = ${book.title}"
}
----

Alternatively you can execute one of the query methods to invoke the query and return an `rx.Observable`:


[source,groovy]
----
Book.where { title == 'The Stand' }
    .list()
    .subscribe { List<Book> books ->
        for (Book book in books) {
            println "Title = ${book.title}"
        }
    }
----

For more information on the syntax of where queries see the https://grails.apache.org/docs/latest/grails-data/hibernate5/manual/index.html#whereQueries[relevant section in the GORM documentation].
