Developers

Writing simple queries using SELECT and FROM


Query 1: Introducing a simple query

To write one of the simplest queries — such a request for a list of everything in the database — use SELECT and FROM clauses like in SQL:


  SELECT *                                
  FROM /

This query utilizes the following reserved words and symbols:

SELECT

Describes the data that you want to see

*

Generates everything known about the device similar to a wildcard; it outputs the entire tree below the anchor-point indicated in the FROM clause

FROM

Describes the anchor-point — the node in the tree that you want to pull data from

/

Represents the root node when the slash is at the start of the path

The results from the query depend on the database that you run it against. If you run this query against the sample batabase, it generates the results in the form of an inverted tree, showing the network and each device in it represented as a sub-tree. If you examine the database that this result came from, you'll see that it contains more information about some devices than about others, which is why some of the results appear more complete than others: 

row: 
  *: 
    network: 
      device: 
        interface: 
          mac_address: 01:01:02:03:04:05
          name: eth0
          in_octets: 1995335536
          out_octets: 248342455
          oper_status: 1
        system: 
          name: 5627
          computed_vendor: LANIER
          computed_model: 5627
          computed_class: printer
          computed_score: 115
        os: 
          version: LANIER 5627 5.20
      device: 
        interface: 
          mac_address: 02:A1:A2:A3:A4:A4
          name: eth0
          in_octets: 1229592351
          out_octets: 1472928781
          oper_status: 1
        interface: 
          mac_address: 03:A1:A2:A3:A4:A5
          name: eth1
          in_octets: 0
          out_octets: 0
          oper_status: 0
        system: 
          name: ESMITH
          computed_vendor: Intel
          computed_class: server
          computed_score: 10
        os: 
          version: Linux
      device: 
        interface: 
          mac_address: 04:A1:A2:A3:A4:A8
          name: eth0
          in_octets: 1223098455
          out_octets: 1523093749
          oper_status: 1
        interface: 
          mac_address: 05:A1:A2:A3:A4:A9
          name: eth1
          in_octets: 0
          out_octets: 0
          oper_status: 0
        system: 
          name: AJONES
          computed_vendor: Intel
          computed_class: server
          computed_score: 10
        os: 
          version: Linux
      device: 
        interface: 
          mac_address: 06:13:72:F3:0A:F5
          name: eth0
          in_octets: 0
          out_octets: 0
          oper_status: 2
        interface: 
          mac_address: 07:13:72:F3:0A:F6
          name: eth1
          in_octets: 0
          out_octets: 0
          oper_status: 2
        system: 
          computed_model: Ethernet Switch
          computed_class: switch
          computed_score: 25
        os: 
          version: Ethernet Switch
      device: 
        interface: 
          mac_address: 08:16:CB:FF:FE:66
          name: eth0
          in_octets: 0
          out_octets: 346
          oper_status: 1
        interface: 
          mac_address: 09:16:CB:FF:FE:67
          name: eth1
          in_octets: 0
          out_octets: 0
          oper_status: 2
        interface: 
          mac_address: 10:16:CB:FF:FE:68
          name: eth2
          in_octets: 0
          out_octets: 0
          oper_status: 2
        interface: 
          mac_address: 11:16:CB:FF:FE:69
          name: eth3
          in_octets: 1598233842
          out_octets: 2360815490
          oper_status: 1
        system: 
          name: PROTON
          computed_model: Windows Workstation
          computed_class: workstation
          computed_score: 125
        os: 
          version: Darwin Kernel Version 9.2.2
      device: 
        interface: 
          mac_address: 12:10:D8:99:2B:C2
          name: eth0
          in_octets: 1385354750
          out_octets: 1451321493
          oper_status: 1
        interface: 
          mac_address: 13:10:D8:99:2B:C1
          name: eth1
          in_octets: 3312952833
          out_octets: 3239791359
          oper_status: 1
        system: 
          name: NISSINGETTY
          computed_vendor: Juniper Networks
          computed_model: Netscreen Router
          computed_class: router
          computed_score: 60
        os: 
          version: NetScreen-5GT 5.1.043a

Query 2: Adding a path in the FROM clause

To add a level of specificity to this simple query, you can write the path to a node level in the FROM clause. This example asks for everything about the network:


  SELECT *
  FROM /network/device

If you run this query on the Sample Database A, it generates the following devices, each represented as a separate tree: 

row
  *
    interface
      mac_address 01:01:02:03:04:05
      name eth0
      in_octets 1995335536
      out_octets 248342455
      oper_status 1
    system
      name 5627
      computed_vendor LANIER
      computed_model 5627
      computed_class printer
      computed_score 115
    os
      version LANIER 5627 5.20
row
  *
    interface
      mac_address 02:A1:A2:A3:A4:A4
      name eth0
      in_octets 1229592351
      out_octets 1472928781
      oper_status 1
    interface
      mac_address 03:A1:A2:A3:A4:A5
      name eth1
      in_octets 0
      out_octets 0
      oper_status 0
    system
      name ESMITH
      computed_vendor Intel
      computed_class server
      computed_score 10
    os
      version Linux
row
  *
    interface
      mac_address 04:A1:A2:A3:A4:A8
      name eth0
      in_octets 1223098455
      out_octets 1523093749
      oper_status 1
    interface
      mac_address 05:A1:A2:A3:A4:A9
      name eth1
      in_octets 0
      out_octets 0
      oper_status 0
    system
      name AJONES
      computed_vendor Intel
      computed_class server
      computed_score 10
    os
      version Linux
row
  *
    interface
      mac_address 06:13:72:F3:0A:F5
      name eth0
      in_octets 0
      out_octets 0
      oper_status 2
    interface
      mac_address 07:13:72:F3:0A:F6
      name eth1
      in_octets 0
      out_octets 0
      oper_status 2
    system
      computed_model Ethernet Switch
      computed_class switch
      computed_score 25
    os
      version Ethernet Switch
row
  *
    interface
      mac_address 08:16:CB:FF:FE:66
      name eth0
      in_octets 0
      out_octets 346
      oper_status 1
    interface
      mac_address 09:16:CB:FF:FE:67
      name eth1
      in_octets 0
      out_octets 0
      oper_status 2
    interface
      mac_address 10:16:CB:FF:FE:68
      name eth2
      in_octets 0
      out_octets 0
      oper_status 2
    interface
      mac_address 11:16:CB:FF:FE:69
      name eth3
      in_octets 1598233842
      out_octets 2360815490
      oper_status 1
    system
      name KRYPTON
      computed_model Windows Workstation
      computed_class workstation
      computed_score 125
    os
      version Darwin Kernel Version 9.2.2
row
  *
    interface
      mac_address 12:10:D8:99:2B:C2
      name eth0
      in_octets 1385354750
      out_octets 1451321493
      oper_status 1
    interface
      mac_address 13:10:D8:99:2B:C1
      name eth1
      in_octets 3312952833
      out_octets 3239791359
      oper_status 1
    system
      name NISSINGETTY
      computed_vendor Juniper Networks
      computed_model Netscreen Router
      computed_class router
      computed_score 60
    os
      version NetScreen-5GT 5.1.043a

Query 3: Making SELECT more specific

To add specificity to this simple query, you can write a specific path to a node in the FROM clause. But you can get much more specific results by narrowing the SELECT clause. Replace the * star with exactly what you want to know, such as name, MAC address, and oeprating status: 


  SELECT name, mac_address, oper_status
  FROM /network/device/interface

Based on the sample database, this query generates a list of interface names: 

row
  name eth0
  mac_address 01:01:02:03:04:05
  oper_status 1
row
  name eth0
  mac_address 02:A1:A2:A3:A4:A4
  oper_status 1
row
  name eth1
  mac_address 03:A1:A2:A3:A4:A5
  oper_status 0
row
  name eth0
  mac_address 04:A1:A2:A3:A4:A8
  oper_status 1
row
  name eth1
  mac_address 05:A1:A2:A3:A4:A9
  oper_status 0
row
  name eth0
  mac_address 06:13:72:F3:0A:F5
  oper_status 2
row
  name eth1
  mac_address 07:13:72:F3:0A:F6
  oper_status 2
row
  name eth0
  mac_address 08:16:CB:FF:FE:66
  oper_status 1
row
  name eth1
  mac_address 09:16:CB:FF:FE:67
  oper_status 2
row
  name eth2
  mac_address 10:16:CB:FF:FE:68
  oper_status 2
row
  name eth3
  mac_address 11:16:CB:FF:FE:69
  oper_status 1
row
  name eth0
  mac_address 12:10:D8:99:2B:C2
  oper_status 1
row
  name eth1
  mac_address 13:10:D8:99:2B:C1
  oper_status 1

Note: Each row in the above results is actually a tree, although it may not look like it. In LISP-like string format, these trees would look like this: (name = 'eth0')(name = 'eth1')(name = 'eth2')(name = 'eth3'), and so on.


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