The database I'm working on is DB2 and I have a problem similar to the following scenario:
Table Structure
-------------------------------
| Teacher Seating Arrangement |
-------------------------------
| PK | seat_argmt_id |
| | teacher_id |
-------------------------------
-----------------------------
| Seating Arrangement |
-----------------------------
|PK FK | seat_argmt_id |
|PK | Row_num |
|PK | seat_num |
|PK | child_name |
-----------------------------
Table Data
------------------------------
| Teacher Seating Arrangement|
------------------------------
| seat_argmt_id | teacher_id |
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 2 |
------------------------------
---------------------------------------------------
| Seating Arrangement |
---------------------------------------------------
| seat_argmt_id | row_num | seat_num | child_name |
| 1 | 1 | 1 | Abe |
| 1 | 1 | 2 | Bob |
| 1 | 1 | 3 | Cat |
| | | | |
| 2 | 1 | 1 | Abe |
| 2 | 1 | 2 | Bob |
| 2 | 1 | 3 | Cat |
| | | | |
| 3 | 1 | 1 | Abe |
| 3 | 1 | 2 | Cat |
| 3 | 1 | 3 | Bob |
| | | | |
| 4 | 1 | 1 | Abe |
| 4 | 1 | 2 | Bob |
| 4 | 1 | 3 | Cat |
| 4 | 2 | 2 | Dan |
---------------------------------------------------
I want to see where there are duplicate seating arrangements for a teacher. And by duplicates I mean where the row_num, seat_num, and child_name are the same among different seat_argmt_id for one teacher_id. So with the data provided above, only seat id 1 and 2 are what I would want to pull back, as they are duplicates on everything but the seat id. If all the children on the 2nd table are exact (sans the primary & foreign key, which is seat_argmt_id in this case), I want to see that.
My initial thought was to do a count(*) group by row#, seat#, and child. Everything with a count of > 1 would mean it's a dupe and = 1 would mean it's unique. That logic only works if you are comparing single rows though. I need to compare multiple rows. I cannot figure out a way to do it via SQL. The solution I have involves going outside of SQL and works (probably). I'm just wondering if there is a way to do it in DB2.
Does this do what you want?
select d.teacher_id, sa.row_num, sa.seat_num, sa.child_name
from seatingarrangement sa join
data d
on sa.seat_argmt_id = d.seat_argmt_id
group by d.teacher_id, sa.row_num, sa.seat_num, sa.child_name
having count(*) > 1;
EDIT:
If you want to find two arrangements that are the same:
select sa1.seat_argmt_id, sa2.seat_argmt_id
from seatingarrangement sa1 join
seatingarrangement sa2
on sa1.seat_argmt_id < sa2.seat_argmt_id and
sa1.row_num = sa2.row_num and
sa1.seat_num = sa2.seat_num and
sa1.child_name = sa2.child_name
group by sa1.seat_argmt_id, sa2.seat_argmt_id
having count(*) = (select count(*) from seatingarrangement sa where sa.seat_argmt_id = sa1.seat_argmt_id) and
count(*) = (select count(*) from seatingarrangement sa where sa.seat_argmt_id = sa2.seat_argmt_id);
This finds the matches between two arrangements and then verifies that the counts are correct.
Related
I have this table discount_user_product structure
discount_id | user_id | product_id
------------+---------+------------
1 | 1 | 1
1 | 1 | 2
1 | 2 | 3
My tables
Users
id | name |
----------+---------+-
1 | Bobby |
2 | Max |
3 | Joj |
Discounts
id | discount | expired_at
----------+----------+------------
1 | 100 |
2 | 50 |
3 | 30 |
Products
id | user_id | title
----------+---------+------------
1 | 1 | Milk
2 | 1 | Chees
3 | 2 | Jeam
I would like to use a better tables structure and decompose discount_user_product to this structure:
discount_user
discount_id | user_id |
------------+---------+-
1 | 1 |
1 | 2 |
user_product
user_id | product_id |
--------+------------+-
1 | 1 |
1 | 2 |
2 | 3 |
Is this will be the right way to make better performance and compliance with the rules of normalizations?
I have 3 tables as shown:
Video
+----+--------+-----------+
| id | name | videoSize |
+----+--------+-----------+
| 1 | video1 | 1MB |
| 2 | video2 | 2MB |
| 3 | video3 | 3MB |
+----+--------+-----------+
Survey
+----+---------+-----------+
| id | name | questions |
+----+---------+-----------+
| 1 | survey1 | 1 |
| 2 | survey2 | 2 |
| 3 | survey3 | 3 |
+----+---------+-----------+
Sequence
+----+---------+-----------+----------+
| id | videoId | surveyId | sequence |
+----+---------+-----------+----------+
| 1 | null | 1 | 1 |
| 2 | 2 | null | 2 |
| 3 | null | 3 | 3 |
+----+---------+-----------+----------+
I would like to query Sequence and join on both of video and survey tables and merge common columns without specifying the column names (in this case name) like this:
Query Result:
+----+---------+-----------+----------+---------+-----------+-----------+
| id | videoId | surveyId | sequence | name | videoSize | questions |
+----+---------+-----------+----------+---------+-----------+-----------+
| 1 | null | 1 | 1 | survey1 | null | 1 |
| 2 | 2 | null | 2 | video2 | 2MB | null |
| 3 | null | 3 | 3 | survey3 | null | 3 |
+----+---------+-----------+----------+---------+-----------+-----------+
Is this possible?
BTW the below sql doesn't work as it doesn't merge on the name field:
SELECT * FROM "Sequence"
LEFT JOIN "Survey" ON "Survey"."id" = "Sequence"."surveyId"
LEFT JOIN "Video" ON "Video"."id" = "Sequence"."videoId"
This query will show what you want:
select
s.*,
coalesce(y.name, v.name) as name, -- picks the right column
v.videoSize,
y.questions
from sequence s
left join survey y on y.id = s.surveyId
left join video v on v.id = s.videoId
However, the SQL standard requires you to name the columns you want. The only exception being * as shown above.
Hi everyone got a little stuck on an sql query. I have four tables
users
+----+------------+-----------+--------+
| id | first_name | last_name | active |
+----+------------+-----------+--------+
| 1 | Joe | Bloggs | 1 |
| 2 | John | Doe | 1 |
| 3 | Dave | Smith | 1 |
+----+------------+-----------+--------+
cases
+----+-----------+-------------+
| id | case_code | case_name |
+----+-----------+-------------+
| 1 | THEC12C | Test Case 1 |
| 2 | ABCD23A | Test Case 2 |
+----+-----------+-------------+
case_creditors
+----+---------+-------------+
| id | case_id | creditor_id |
+----+---------+-------------+
| 1 | 1 | 3 |
| 2 | 2 | 1 |
+----+---------+-------------+
case_files
+----+---------+----------+-----------+
| id | case_id | filename | file type |
+----+---------+----------+-----------+
| 1 | 1 | test.pdf | pfd |
| 2 | 2 | file.txt | txt |
| 3 | 2 | word.doc | doc |
+----+---------+----------+-----------+
When a user logs in i need to show a table with the users accociated cases the number of files attached to that case so if Joe Blogs loged in head see the following table
+-----------+-------------+-------+
| Case Code | Case Name | Files |
+-----------+-------------+-------+
| ABCD23A | Test Case 2 | 2 |
+-----------+-------------+-------+
ive been trying to write the sql statement to do this but am getting stuck on the query and wandered if someone could help give me some pointers. the sql ive gor so far
SELECT * FROM cases
(SELECT COUNT(*) FROM case_files WHERE case_files.case_id = cases.id) as Files
JOIN case_creditors ON cases.id = case_creditors.case_id
WHERE case_creditors.creditor_id = 1
managed to sort this with
SELECT
ips_case.*,
COUNT(case_files.file_id) AS Files
FROM
ips_case
LEFT JOIN case_files ON ips_case.id = case_files.case_id
JOIN case_creditors ON ips_case.id = case_creditors.case_id
WHERE
case_creditors.creditors_id = 4
GROUP BY
ips_case.id
I have a table which represents the hierarchy of departments:
+-----------+--------------+--------------+--------------+-----------+-------+
| Top Dept. | 2-tier Dept. | 3-tire Dept. | 4-tier Dept. | name | tier |
+-----------+--------------+--------------+--------------+-----------+-------+
| 00 | | | | abc | 0 |
| | 00-01 | | | bcd | 1 |
| | | 00-01-01 | | cde | 2 |
| | | 00-01-02 | | abc | 2 |
| | 00-02 | | | aef | 1 |
| | | 00-02-01 | | qwe | 2 |
| | | 00-02-03 | | abc | 2 |
| | | | 00-02-03-01 | abc | 3 |
+-----------+--------------+--------------+--------------+-----------+-------+
now I want to sort the rows which are in the same tier by their names while keeping the hierarchy overall, That's what I expect:
+-----------+--------------+--------------+--------------+-----------+-------+
| Top Dept. | 2-tier Dept. | 3-tire Dept. | 4-tier Dept. | name | tier |
+-----------+--------------+--------------+--------------+-----------+-------+
| 00 | | | | abc | 0 |
| | 00-02 | | | aef | 1 |
| | | 00-02-03 | | abc | 2 |
| | | 00-02-01 | | qwe | 2 |
| | 00-01 | | | def | 1 |
| | | 00-01-02 | | abc | 2 |
| | | 00-01-01 | | cde | 2 |
| | | | 00-02-03-01 | abc | 3 |
+-----------+--------------+--------------+--------------+-----------+-------+
the missing data means null, I'm using Oracle DB, can anyone help me?
EDIT: Actually, it's a simple version of this sql, I've tried to add a new column which concats the values of the first four columns and then order by it and by name, but it did't work.
Update: This appears to be working... SQL Fiddle
All that was really needed from my original comment was to amend name to department in that order in both selects. This allows the engine to sort by name first, while maintaining the hierarchy.
WITH cte(Dept, superiorDept, name, depth, sort)AS (
SELECT
Dept,
superiorDept,
name,
0,
name|| dept
FROM hierarchy h
WHERE superiorDept IS NULL
UNION ALL
SELECT
h2.Dept,
h2.superiorDept,
h2.name,
cte.depth + 1,
cte.sort || h2.name ||h2.dept
FROM hierarchy h2
INNER JOIN cte ON h2.superiorDept = cte.Dept
)
SELECT
CASE WHEN depth = 0 THEN Dept END AS 一级部门,
CASE WHEN depth = 1 THEN Dept END AS 二级部门,
CASE WHEN depth = 2 THEN Dept END AS 三级部门,
CASE WHEN depth = 3 THEN Dept END AS 四级部门,
name,
depth,
sort
FROM cte
ORDER BY sort, name
I have 3 like with many - many relationship
As:
TABLE 1 : select * from student;
| id | name |
| 1 | sone |
| 2 | stwo |
| 3 | sthree |
| 4 | sfour |
| 6 | ssix |
TABLE 2 : select * from course;
| id | name |
| 100 | CSE |
| 101 | ECE |
| 102 | ITI |
RELATION_SHIP TABLE : select * from student_course
| id | stu_id | cou_id |
| 1 | 1 | 101 |
| 2 | 2 | 102 |
| 3 | 2 | 100 |
| 4 | 3 | 100 |
| 5 | 3 | 101 |
| 6 | 1 | 101 |
| 1 | 6 | 101 |
I need to write a query to select a student with exactly one course 'CSE' and he should not have any other courses.
Thanks in advance
Use query:
SELECT
sc.`stu_id`,
COUNT(sc.`cou_id`) AS cnt
FROM
student_course sc
GROUP BY sc.`stu_id`
HAVING cnt = 1
AND GROUP_CONCAT(cou_id) LIKE
(SELECT
id
FROM
course
WHERE NAME = 'CSE')