== Running XSQL Console Commands and Queries

//* <<XSQL Overview>>
//* <<Installing XSQL>>
//* <<XSQL Console Commands>>
//* <<XSQL Queries>>
//** <<Example: skip Criteria Operator>>
:toc:

=== XSQL Overview

XSQL is an XML-based query language that describes simple stored procedures
which parse XML data, query or update database tables, and compose XML output.
XSQL allows you to query tree models like a sequential database. For example,
you could run a query that lists all of the ports configured on a particular
module and their attributes.

The following sections cover the XSQL installation process, supported XSQL
commands, and the way to structure queries.

=== Installing XSQL

To run commands from the XSQL console, you must first install XSQL on your
system:

. Navigate to the directory in which you unzipped OpenDaylight
. Start Karaf:
+
 ./bin/karaf
+
. Install XSQL:
+
 feature:install odl-mdsal-xsql

=== XSQL Console Commands

To enter a command in the XSQL console, structure the command as follows:
*odl:xsql* _<XSQL command>_

The following table describes the commands supported in this OpenDaylight
release.

.Supported XSQL Console Commands
[cols="30%,70%",options="headers"]
|==============================================
| *Command* | *Description*
| *r*
| Repeats the last command you executed.
| *list vtables*
| Lists the schema node containers that are currently installed. Whenever an
OpenDaylight module is installed, its YANG model is placed in the schema
context. At that point, the  XSQL receives a notification, confirms that the
module's YANG model resides in the schema context and then maps the model to
XSQL by setting up the necessary vtables and vfields. This command is useful
when you need to determine vtable information for a query.
| *list vfields* _<vtable name>_
| Lists the vfields present in a specific vtable. This command is useful when
you need to determine vfields information for a query.
| *jdbc* _<ip address>_
| When the ODL server is behind a firewall, and the JDBC client cannot connect
to the JDBC server, run this command to start the client as a server and
establish a connection.
| *exit*
| Closes the console.
| *tocsv*
| Enables or disables the forwarding of query output as a .csv file.
| *filename* _<filename>_
| Specifies the .tocsv file to which the query data is exported. If you do not
specify a value for this option when the toccsv option is enabled, the filename
for the query data file is generated automatically.
|==============================================

=== XSQL Queries

You can run a query to extract information that meets the criteria you specify
using the information provided by the *list vtables* and *list vfields* 
_<vtable name>_ commands.  Any query you run should be structured as follows:

*select* _<vfields you want to search for, separated by a comma and a space>_
*from* _<vtables you want to search in, separated by a comma and a space>_
*where* _<criteria>_ *'*_<criteria operator>_*';*

For example, if you want to search the nodes/node ID field in the
nodes/node-connector table and find every instance of the Hardware-Address
object that contains _BA_ in its text string, enter the following query:

 select nodes/node.ID from nodes/node-connector where Hardware-Address like '%BA%';

The following criteria operators are supported:

.Supported XSQL Query Criteria Operators
[cols="20%,80%",options="headers"]
|==============================================
| *Criteria Operators* | *Description*
| *=*        | Lists results that equal the value you specify.
| *!=*       | Lists results that do not equal the value you specify.
| *like*     | Lists results that contain the substring you specify. For
               example, if you specify *like %BC%*, every string that contains
               that particular substring is displayed.
| *<*        | Lists results that are less than the value you specify.
| *>*        | Lists results that are more than the value you specify.
| *and*      | Lists results that match both values you specify.
| *or*       | Lists results that match either of the two values you specify.
| *>=*       | Lists results that are more than or equal to the value you specify.
| *<=*       | Lists results that are less than or equal to the value you specify.
| *is null*  | Lists results for which no value is assigned.
| *not null* | Lists results for which any value is assigned.
| *skip*     | Use this operator to list matching results from a child node,
               even if its parent node does not meet the specified criteria.
               See the following example for more information.
|==============================================

==== Example: Skip Criteria Operator

If you are looking at the following structure and want to determine all of the
ports that belong to a YY type module:

* Network Element 1
** Module 1, Type XX
*** Module 1.1, Type YY
**** Port 1
**** Port 2
** Module 2, Type YY
*** Port 1
*** Port 2

If you specify *Module.Type='YY'* in your query criteria, the ports associated
with module 1.1 will not be returned since its parent module is type XX.
Instead, enter *Module.Type='YY' or skip Module!='YY'*. This tells XSQL to
disregard any parent module data that does not meet the type YY criteria and
collect results for any matching child modules. In this example, you are
instructing the query to skip module 1 and collect the relevant data from
module 1.1.