com.couchbase.lite

Class Query

java.lang.Object

com.couchbase.lite.Query

Direct Known Subclasses:

From, GroupBy, Having, Joins, Limit, OrderBy, Select, Where

public class Query
extends Object

A database query used for querying data from the database. The query statement of the Query object can be fluently constructed by calling the static select methods.

Method Summary

Modifier and Type	Method and Description
ListenerToken	addChangeListener(QueryChangeListener listener)
ResultSet	execute() Executes the query.
String	explain() Returns a string describing the implementation of the compiled query.
Database	getDatabase()
Parameters	getParameters() Returns a copies of the current parameters.
void	removeChangeListener(ListenerToken token)
static Select	select(SelectResult... results) Create a SELECT ALL (*) query.
static Select	selectDistinct(SelectResult... results) Create a SELECT DISTINCT ALL (*) query.
void	setParameters(Parameters parameters) Set parameters should copy the given parameters.
String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Method Detail

select

public static Select select(SelectResult... results)

Create a SELECT ALL (*) query. You can then call the Select object's methods such as from() method to construct the complete Query object.

Returns:

the Select object.

selectDistinct

public static Select selectDistinct(SelectResult... results)

Create a SELECT DISTINCT ALL (*) query. You can then call the Select object's methods such as from() method to construct the complete Query object.

Returns:

the Select object.

getParameters

public Parameters getParameters()

Returns a copies of the current parameters.

setParameters

public void setParameters(Parameters parameters)

Set parameters should copy the given parameters. Set a new parameter will also re-execute the query if there is at least one listener listening for changes.

execute

public ResultSet execute()
                  throws CouchbaseLiteException

Executes the query. The returning a result set that enumerates result rows one at a time. You can run the query any number of times, and you can even have multiple ResultSet active at once.

The results come from a snapshot of the database taken at the moment the run() method is called, so they will not reflect any changes made to the database afterwards.

Returns:

the ResultSet for the query result.

Throws:

CouchbaseLiteException - if there is an error when running the query.

explain

public String explain()
               throws CouchbaseLiteException

Returns a string describing the implementation of the compiled query. This is intended to be read by a developer for purposes of optimizing the query, especially to add database indexes. It's not machine-readable and its format may change. As currently implemented, the result is two or more lines separated by newline characters: * The first line is the SQLite SELECT statement. * The subsequent lines are the output of SQLite's "EXPLAIN QUERY PLAN" command applied to that statement; for help interpreting this, see https://www.sqlite.org/eqp.html . The most important thing to know is that if you see "SCAN TABLE", it means that SQLite is doing a slow linear scan of the documents instead of using an index.

Returns:

a string describing the implementation of the compiled query.

Throws:

CouchbaseLiteException - if an error occurs

addChangeListener

public ListenerToken addChangeListener(QueryChangeListener listener)

removeChangeListener

public void removeChangeListener(ListenerToken token)

toString

public String toString()

Overrides:

toString in class Object

getDatabase

public Database getDatabase()