How to identify pattern in SQL - sql

Question

This is my table. It does consist of A,B and C columns. Only one column value will be true at one time.
My task is to identify pattern based on latest five rows.
For example
I need to search entire table to find whenever these five values were repeated.
If they were repeated, what was the next value avilable for these pattern and show how many times does A, B and C values were found after the pattern.
How this can be done in SQL? I am using oracle 11g. Thanks.

Answer 1

You can convert your a, b, c value to a trinary number and then calculate a value for that row and the previous 4 as if the trinary values for the rows comprised a 5-digit trinary number and then use analytic functions to find the next occurrence and to count the occurrences:
SELECT id,
a,
b,
c,
CASE
WHEN grp_value IS NULL
THEN NULL
ELSE MIN(id) OVER (
PARTITION BY grp_value
ORDER BY id
ROWS BETWEEN 1 FOLLOWING AND UNBOUNDED FOLLOWING
) + 1
END AS row_after_next_match,
CASE
WHEN grp_value IS NULL
THEN 0
ELSE COUNT(id) OVER ( PARTITION BY grp_value )
END AS num_matches
FROM (
SELECT id,
a,
b,
c,
value,
81 * LAG(value,4) OVER ( ORDER BY id ) +
27 * LAG(value,3) OVER ( ORDER BY id ) +
9 * LAG(value,2) OVER ( ORDER BY id ) +
3 * LAG(value,1) OVER ( ORDER BY id ) +
1 * value AS grp_value
FROM (
SELECT id,
a,
b,
c,
DECODE(1,a,0,b,1,c,2) AS value
FROM table_name
)
)
ORDER BY id
Which, for the sample data:
CREATE TABLE table_name (
id PRIMARY KEY,
a,
b,
c,
CHECK (a IN (0,1)),
CHECK (b IN (0,1)),
CHECK (c IN (0,1)),
CHECK (a+b+c = 1)
) AS
SELECT 1, 1, 0, 0 FROM DUAL UNION ALL
SELECT 2, 1, 0, 0 FROM DUAL UNION ALL
SELECT 3, 0, 1, 0 FROM DUAL UNION ALL
SELECT 4, 1, 0, 0 FROM DUAL UNION ALL
SELECT 5, 0, 1, 0 FROM DUAL UNION ALL
SELECT 6, 0, 0, 1 FROM DUAL UNION ALL
SELECT 7, 1, 0, 0 FROM DUAL UNION ALL
SELECT 8, 0, 1, 0 FROM DUAL UNION ALL
SELECT 9, 1, 0, 0 FROM DUAL UNION ALL
SELECT 10, 0, 1, 0 FROM DUAL UNION ALL
SELECT 11, 0, 0, 1 FROM DUAL UNION ALL
SELECT 12, 1, 0, 0 FROM DUAL UNION ALL
SELECT 13, 1, 0, 0 FROM DUAL UNION ALL
SELECT 14, 1, 0, 0 FROM DUAL UNION ALL
SELECT 15, 1, 0, 0 FROM DUAL UNION ALL
SELECT 16, 1, 0, 0 FROM DUAL UNION ALL
SELECT 17, 1, 0, 0 FROM DUAL UNION ALL
SELECT 18, 1, 0, 0 FROM DUAL UNION ALL
SELECT 19, 1, 0, 0 FROM DUAL UNION ALL
SELECT 20, 1, 0, 0 FROM DUAL
Outputs:
ID
A
B
C
ROW_AFTER_NEXT_MATCH
NUM_MATCHES
1
1
0
0
0
2
1
0
0
0
3
0
1
0
0
4
1
0
0
0
5
0
1
0
1
6
0
0
1
12
2
7
1
0
0
13
2
8
0
1
0
1
9
1
0
0
1
10
0
1
0
1
11
0
0
1
2
12
1
0
0
2
13
1
0
0
1
14
1
0
0
1
15
1
0
0
1
16
1
0
0
18
5
17
1
0
0
19
5
18
1
0
0
20
5
19
1
0
0
21
5
20
1
0
0
5
db<>fiddle here