I have two tables (as seen bellow) and i want to join them and select the person who has multiple values form the second table. The first table is a list of all people and their unique IDs, the second table is a list of peoples favorite colors.
Table A.: Unique ID | Name
+-----+-------------+
| uid | name |
+-----+-------------+
| 321 | Ana |
| 662 | Nick |
| 003 | Fred |
+-----+-------------+
Table B.: Table ID | Unique ID | Color ID
+----------+--------+-----------+
| id | uid | color_id |
+----------+--------+-----------+
| 1 | 121 | 1 |
| 2 | 127 | 2 |
| 3 | 003 | 11 |
| 4 | 002 | 11 |
| 5 | 111 | 3 |
| 6 | 044 | 5 |
| 7 | 003 | 5 |
| 8 | 003 | 8 |
+----------+--------+-----------+
So i want to select only the users (uid) who matches all the colors given, for example 11 and 8 (red and fusia). In this case that would be user 003 | Fred, and only have 1 row per match, and not multiple (for each value).
I have tried using where color_id IN (x,y,z...) but this will return any person who has at least 1 color in the list
You can try below -
select uniqueid, name from tableA a
inner join tableB b on a.uniqueid=b.uid
where color_id in (11,8)
group by uniqueid, name
having count(distinct color_id)=2
you can do your wish by
select distinct tableA.uid, tableA.name tableB.color_id from tableA
inner join tableB on tableA.uniqueid=tableB.uid
group by tableA.uid , tableA.name ,tableB.color_id
having count(distinct color_id)=2
Related
I have a table like below (refer table 1) , which can have multiple ids. I want to split the Reviewer id and get the first name and last name from table 2 and display in table 1 column 2 and 3 using sql.
Table 1
| Reviewer id/s| Name 1 |Name 2|
| -------------| -------|------|
| 123; 124 | row | row |
| 126; 156 | row | row |
Table 2
| Reviewer id | First Name |Last name |
| -------------| -----------|----------|
| 123 | Apple | A |
| 124 | Banana | B |
| 125 | Rose | Rose |
| 156 | Orange | I |
| 157 | Purple | J |
Try this
select value,first_name,last_name from Tabel1 cross apply string_split(Reviewer_id,';') inner join Table2 on Tabel2.Reviewer_id=value
Test here
SQL DEMO
I have 3 tables
QUESTION table with below 2 properties
1. ID (serial)
2. Question (varchar)
ANSWER table with below 4 properties
1. ID (serial)
2. QuestionID (foreign key to table QUESTION)
3. StudentID (foreign key to table STUDENT)
4. ANSWER (varchar)
5. SubmitDateTime (datetime)
STUDENT table with below properties
1. ID (serial)
2. Name (varchar)
I just want to show records with each student (one record for each student) with every answer. If any question's answer is not given by the student it will show blank.
For example:
QUESTION TABLE
| ID | QUESTION |
|----- | --------- |
| 1 | A FOR? |
| 2 | B FOR? |
| 3 | C FOR? |
ANSWER TABLE
| ID | QuestionID | StudentID | ANSWER | SubmitDateTime |
|----- | ----------- |------------|--------|----------------|
| 1 | 1 | 1 |Apple | something date |
| 2 | 1 | 2 |Ant | something date |
| 3 | 2 | 1 |Book | something date |
| 4 | 3 | 2 |Cat | something date |
STUDENT TABLE
| ID | NAME |
|----- | --------- |
| 1 | Jhon |
| 2 | Lily |
Expected Records
Result table
| ID | NAME | Answers |
|----- | --------- | ---------------------|
| 1 | Jhon | Apple,Book,<blank> |
| 2 | Lily | Ant,<blank>,Cat |
"blank" means no record will be shown instead of a blank space or a hyphane.
My implementation:
SELECT s.ID,s.Name,
GROUP_CONCAT(a.answer SEPARATOR ',') AS answers
FROM student AS s
LEFT JOIN answer AS a ON a.studentID=s.ID
WHERE a.submitdate BETWEEN '<somedate>' AND '<somedate>'
GROUP BY s.ID ORDER BY a.ID ASC
It does not give me a blank answer. How to get these?
Try this:
SELECT sid, sname, GROUP_CONCAT(IFNULL(a.answer,'-') ORDER BY qid)
FROM
(SELECT q.id AS qid, s.id AS sid, s.Name AS sname
FROM question q CROSS JOIN student s) qs
LEFT JOIN answer a ON qs.qid=a.QuestionID AND qs.sid=a.StudentID
GROUP BY sid, sname;
The base query is a CROSS JOIN between question and student tables that will be a subquery and give a result like this:
+-----+-----+-------+
| qid | sid | sname |
+-----+-----+-------+
| 1 | 2 | Lily |
| 1 | 1 | Jhon |
| 2 | 2 | Lily |
| 2 | 1 | Jhon |
| 3 | 2 | Lily |
| 3 | 1 | Jhon |
+-----+-----+-------+
As you can see, each of the student will be paired with all of the existing question regardless of their answer records in answer table. This will be the reference for the LEFT JOIN with answer table.
Demo fiddle
I have a ( Joomla) database table called field_values, the contents are below;
+----+----------+---------+---------+
| id | field_id | item_id | value |
+----+----------+---------+---------+
| 1 | 2 | 446 | Jones |
| 2 | 2 | 447 | Smith |
| 3 | 2 | 448 | Jenkins |
| 4 | 3 | 446 | Paul |
| 5 | 3 | 447 | Peter |
| 6 | 3 | 448 | Sally |
| 7 | 4 | 446 | London |
| 8 | 4 | 447 | Dublin |
| 9 | 4 | 448 | Paris |
+----+----------+---------+---------+
I'm only displaying 9 rows from the table, but I actually have thousands, so the successful query would need to take this into account.
Columns explained;
id (primary / auto-increment)
field_id (FK to another fields table, 2 = surname, 3 = first name, 4 = location)
item_id (FK to another users table)
value (contents of field)
How can I select all the values from the above table but display them as follows;
+------------+-----------+----------+
| first_name | last_name | location |
+------------+-----------+----------+
| Paul | Jones | London |
| Peter | Smith | Dublin |
| Sally | Jenkins | Paris |
+------------+-----------+----------+
The id field isn't really necessary in the desired results above, I just added it to emphasise that each row is unique.
I'm not sure if I need to use a subquery or group by, maybe neither?
Thanks in advance.
A pivot query should work here:
SELECT
MAX(CASE WHEN field_id = 3 THEN value END) AS first_name,
MAX(CASE WHEN field_id = 2 THEN value END) AS last_name,
MAX(CASE WHEN field_id = 4 THEN value END) AS location
FROM yourTable
GROUP BY
item_id
ORDER BY
item_id;
Your current table structure is a denormalized key value store, a style which WordPress uses in some of its tables.
you could avoid subquery and grou by.
You could use the same table 3 times
select a.id, b.value firts_name, a.value last_name , c.value location
from field_values a
inner join field_values b on a.item_id = b.item_id and b.field_id = 3
inner join field_values bc on a.item_id = c.item_id and b.field_id = 4
where a.item_id = 2
I have these two tables:
Student:
| name | email |
|---------------------|-------------------------|
| Arturo Vidal | arturo.vidal#usm.cl |
| Bastian Quezada | bastian#usm.cl |
| Javier Jeria | javier#usm.cl |
| Sebastian Piñera | sebastian#presidente.cl |
| Sebastian Gallardo | sebastian#usm.cl |
Class:
| classId | email | signUpDate |
|---------|-------------------------|-------------|
| 1 | sebastian#usm.cl | 2018-01-01 |
| 1 | javier#usm.cl | 2019-10-01 |
| 1 | bastian#usm.cl | 2018-07-01 |
| 2 | sebastian#usm.cl | 2018-05-04 |
| 2 | bastian#usm.cl | 2018-01-01 |
| 3 | bastian#usm.cl | 2018-12-05 |
| 3 | sebastian#usm.cl | 2018-02-01 |
| 4 | arturo.vidal#usm.cl | 2018-03-01 |
| 5 | sebastian#presidente.cl | 2018-03-01 |
I want to show the name the last student that signed up for each classId. That means, I should get a name for classId 1, one for classId 2, etc. My solution for firstly getting the mails (to know the student's name after) is this:
select classId, email, max(signUpDate)
from Class
group by classId
it prints the max date, which is ok, but it also prints the wrong mails for each date:
| ClassId | email | max(signUpDate) |
|---------|-------------------------|-----------------|
| 1 | sebastian#usm.cl | 2019-10-01 |
| 2 | sebastian#usm.cl | 2018-05-04 |
| 3 | bastian#usm.cl | 2018-12-05 |
| 4 | arturo.vidal#usm.cl | 2018-03-01 |
| 5 | sebastian#presidente.cl | 2018-03-01 |
which is completely wrong (). Therefore, when I try to join the the values for getting the names, I get incorrect values.
In other words, I don't understand why are the rows mixing up. Is there any solution for getting correct emails for the max(signUpDate) for each ClassId?
Thanks for your time
i have created the test data fiddle and made an easy and understandable query to fetch the required data, i.e:
SELECT DISTINCT classId,
std.name,
Class.email,
signUpDate
FROM CLASS
INNER JOIN Student std ON std.email = Class.email
WHERE signUpDate IN
(SELECT max(signUpDate)
FROM CLASS
GROUP BY classId)
Sql Fiddle here
This is an instance of a very common class of questions: find the whole row FOR EACH GROUP of the field that maximizes some value (in the group). In your case, you want to GROUP BY the ClassId, and FOR EACH ONE OF THESE GROUPS, you want the whole row of the field with the maximum signupDate.
SHORT ANSWER: You can use this query:
SELECT
C.ClassId,
S.name
FROM
(
SELECT A.*
FROM Class AS A
LEFT JOIN Class AS B
ON A.email = B.email AND A.signupDate < B.signupDate
WHERE B.email IS NULL
) AS C
LEFT JOIN Student AS S ON S.email=C.email
LONG ANSWER:
Here you can find a very clear explanation of what I have just said.
Assuming that we can use the e-mail at your tables as unique identifier, you can do FIRST a join (on the e-mail field) of the table "Class" with itself, to select the "maximum date" for each class id. After that, you join (on the e-mail field) with the table "Student". After that, you will have a table with all the fields of the "Class" table and all the fields of the "Student" table. You can select the fields that you need. In the following example, I will select "Class.classId" and "Student.name"
If you run this query:
SELECT A.*
FROM Class AS A
LEFT JOIN Class AS B
ON A.email = B.email AND A.signupDate < B.signupDate
WHERE B.email IS NULL
You obtain this table:
+---------+-------------------------+------------+
| ClassId | email | signupDate |
+---------+-------------------------+------------+
| 1 | javier#usm.cl | 2019-10-01 |
| 2 | sebastian#usm.cl | 2018-05-04 |
| 3 | bastian#usm.cl | 2018-12-05 |
| 4 | arturo.vidal#usm.cl | 2018-03-01 |
| 5 | sebastian#presidente.cl | 2018-03-01 |
+---------+-------------------------+------------+
Now you can join this with the table "Student", and select the fields that you want. If you run the query provided in the "short answer" part of this post, you get the following result:
+---------+--------------------+
| ClassId | name |
+---------+--------------------+
| 4 | Arturo Vidal |
| 3 | Bastian Quezada |
| 1 | Javier Jeria |
| 5 | Sebastian Piñera |
| 2 | Sebastian Gallardo |
+---------+--------------------+
Try this:
SELECT A.classId, C.name, C.email, B.signUpDate
FROM
(SELECT classId, max(signUpDate) maxSignUpDate
FROM Class
GROUP BY classId) A JOIN Class B
ON A.classId=B.classId AND A.maxSignUpDate=B.signUpDate
JOIN Student C ON C.email=B.email;
I assume the email to be the ID field of the Student table. See MySQL Join Made Easy and MySQL GROUP BY for insights.
See it run on SQL Fiddle.
Please consider two tables with names. They are joined by Table A id, so that two names get associated.
Is there a MySQL query that returns distinct pair of names regardless the order?
First table:
table_a
+-----------+--------------+
| id | name |
+-----------+--------------+
| 1 | John |
+-----------+--------------+
| 2 | Jane |
+-----------+--------------+
| 3 | Jane |
+-----------+--------------+
| 4 | Sammy |
+-----------+--------------+
Second Table:
table_b
+-----------+-------------------+-------------+
| id | id_table_a | name |
+-----------+-------------------+-------------+
| 1 | 1 | Jane |
+-----------+-------------------+-------------+
| 2 | 2 | John |
+-----------+-------------------+-------------+
| 3 | 3 | Sammy |
+-----------+-------------------+-------------+
| 4 | 4 | Tara |
+-----------+-------------------+-------------+
Desired result
(John, Jane)
(Jane, Sammy)
(Sammy, Tara)
Thanks in advance!
Here's one option using least and greatest:
select distinct least(a.name, b.name), greatest(a.name, b.name)
from table_a a
join table_b b on a.id = b.id_table_a
SQL Fiddle Demo