1
00:00:00,000 --> 00:00:07,945


2
00:00:07,945 --> 00:00:09,320
PROFESSOR: In this
section, we're

3
00:00:09,320 --> 00:00:13,050
going to be talking about
updating data, deleting data,

4
00:00:13,050 --> 00:00:14,960
and we're going to
learn a few new commands

5
00:00:14,960 --> 00:00:16,935
and functions within Neo4j.

6
00:00:16,935 --> 00:00:18,560
In this first section,
we'll be talking

7
00:00:18,560 --> 00:00:22,580
about updating existing
nodes and relationships,

8
00:00:22,580 --> 00:00:26,900
using new keywords to find
data, deleting nodes, detaching

9
00:00:26,900 --> 00:00:30,950
relationships, and detaching
and deleting nodes.

10
00:00:30,950 --> 00:00:33,050
In this first
video, we'll go over

11
00:00:33,050 --> 00:00:36,590
some of the capabilities of the
MERGE statement in preparation

12
00:00:36,590 --> 00:00:38,090
of the rest of the video.

13
00:00:38,090 --> 00:00:40,880
And then we'll look at
the commands of MERGE,

14
00:00:40,880 --> 00:00:44,490
the conditions that happen
when you create a new node,

15
00:00:44,490 --> 00:00:46,730
as well as the conditions
that happen when

16
00:00:46,730 --> 00:00:48,800
you match an existing node.

17
00:00:48,800 --> 00:00:52,610
We'll also use MERGE
where we could use MATCH

18
00:00:52,610 --> 00:00:56,060
and SET to change attributes.

19
00:00:56,060 --> 00:00:58,700
To review, we have
a basic data model

20
00:00:58,700 --> 00:01:01,230
set up with actors and movies.

21
00:01:01,230 --> 00:01:05,610
Our goal was to solve the six
degrees of Kevin Bacon problem.

22
00:01:05,610 --> 00:01:10,380
This first MERGE statement
will find an actor with the ID1

23
00:01:10,380 --> 00:01:11,940
and will show its information.

24
00:01:11,940 --> 00:01:15,300
In the Neo4j web
browser, we can type

25
00:01:15,300 --> 00:01:23,520
merge parentheses lowercase A
as in Alias, actor as the label.

26
00:01:23,520 --> 00:01:30,510
We can specify the ID of 1 to
filter, and we can return a.

27
00:01:30,510 --> 00:01:32,550
When we execute
this statement, we

28
00:01:32,550 --> 00:01:38,010
should receive one node
representing Kevin Bacon.

29
00:01:38,010 --> 00:01:42,070
We can look in the rows, the
texts to show more raw results.

30
00:01:42,070 --> 00:01:46,230
We can show all the attributes
for this Kevin Bacon actor.

31
00:01:46,230 --> 00:01:50,520
We can also use MERGE
to create new nodes.

32
00:01:50,520 --> 00:01:54,000
Here we'll create a new
actor node with the ID of 99

33
00:01:54,000 --> 00:01:54,960
and we'll return it.

34
00:01:54,960 --> 00:02:01,730
Again, we'll type merge, a,
an Alias actor, ID of 99,

35
00:02:01,730 --> 00:02:03,470
and will return a.

36
00:02:03,470 --> 00:02:07,560
We know this data doesn't
exist since we only set up--

37
00:02:07,560 --> 00:02:11,000
we know this data doesn't exist
because we only set up actors 1

38
00:02:11,000 --> 00:02:12,410
through 7 or so.

39
00:02:12,410 --> 00:02:15,980
So when we execute this,
it will create a new node

40
00:02:15,980 --> 00:02:19,040
with no attributes,
oops, because we only

41
00:02:19,040 --> 00:02:23,600
supplied the ID parameter
or the ID attribute

42
00:02:23,600 --> 00:02:25,110
in the MERGE statement.

43
00:02:25,110 --> 00:02:28,850
What we should have done
to create a new actor

44
00:02:28,850 --> 00:02:32,030
node with more attributes
is specify those attributes

45
00:02:32,030 --> 00:02:33,500
within the MERGE statement.

46
00:02:33,500 --> 00:02:36,800
Here we're going to make
an actor with the ID of 99

47
00:02:36,800 --> 00:02:40,280
and the name of George George.

48
00:02:40,280 --> 00:02:42,810
When we execute that
Cipher statement,

49
00:02:42,810 --> 00:02:48,410
we'll see the new actor
created with the ID of 99.

50
00:02:48,410 --> 00:02:53,570
Now the problem is we ran the
merge twice with an ID of 99.

51
00:02:53,570 --> 00:02:56,310
So if we run it again
without the name,

52
00:02:56,310 --> 00:03:00,390
this should match on all
nodes with the ID of 99,

53
00:03:00,390 --> 00:03:06,330
and in this case, we will
get our two actor nodes.

54
00:03:06,330 --> 00:03:10,170
The MERGE statement can also
act like an insert or update

55
00:03:10,170 --> 00:03:13,740
statement or construct within
traditional database systems.

56
00:03:13,740 --> 00:03:16,200
Using the MERGE
statement, you can

57
00:03:16,200 --> 00:03:18,540
create a condition
called ON CREATE

58
00:03:18,540 --> 00:03:22,230
and you can execute or
update specific values.

59
00:03:22,230 --> 00:03:25,140
You can also set the
condition for ON MATCH where

60
00:03:25,140 --> 00:03:26,590
you can do something else.

61
00:03:26,590 --> 00:03:31,350
In this case, we'll create a
new actor with the ID of 98.

62
00:03:31,350 --> 00:03:34,740
When it's created, we'll
set the name to Mark Hamill

63
00:03:34,740 --> 00:03:36,550
and we'll add a counter field.

64
00:03:36,550 --> 00:03:40,320
We haven't done this yet, but
we'll add a counter field of 0.

65
00:03:40,320 --> 00:03:46,530
If we rerun this MERGE statement
and the condition of ID 99

66
00:03:46,530 --> 00:03:51,240
is already met, we'll execute
the statements ON MATCH section

67
00:03:51,240 --> 00:03:54,820
where we'll set the counter
to the counter plus 1,

68
00:03:54,820 --> 00:03:57,710
effectively incrementing
the counter every time

69
00:03:57,710 --> 00:03:59,330
we merge on this node.

70
00:03:59,330 --> 00:04:00,620
Let's try it out.

71
00:04:00,620 --> 00:04:03,380
You'll see here we can
type this MERGE statement,

72
00:04:03,380 --> 00:04:05,300
merge, actor ID 98.

73
00:04:05,300 --> 00:04:11,270
ON CREATE, we'll set the name to
Mark Hamill with a counter of 0.

74
00:04:11,270 --> 00:04:16,279
ON MATCH, we'll set the
counter to counter plus 1

75
00:04:16,279 --> 00:04:18,089
and we'll return the actor node.

76
00:04:18,089 --> 00:04:21,380
Here we'll execute it and
we should see our new node.

77
00:04:21,380 --> 00:04:26,330
If we look at the raw results
we'll see a counter of 0.

78
00:04:26,330 --> 00:04:27,300
So using the browser.

79
00:04:27,300 --> 00:04:30,110
We can click on the
Cipher statement again.

80
00:04:30,110 --> 00:04:32,960
Press it again, our
counter will increment.

81
00:04:32,960 --> 00:04:36,230
And every time we
execute this since we're

82
00:04:36,230 --> 00:04:40,610
matching on the ID of 98,
our counter increments.

83
00:04:40,610 --> 00:04:43,370
So this shows the
two conditions we

84
00:04:43,370 --> 00:04:48,310
have used in the MERGE statement
ON CREATE and ON MATCH.

85
00:04:48,310 --> 00:04:57,000