hello every one please help me regarding how to make a good query to fetch the data from three table. I am making a database in which there will be users , employee and services which will provided to users via employee so i have set that table name as task. Now i can add the task by fetching the data from different table , the thing right now i want to do is show the entire record by fetching all the client data and services available to him and and who will be going to perform that services . so how can i put the query on the task table to fetch the data from the other table. Thanks
**task table**
task_id user_id employee_id service_id starttime endtime date
by using this table i have to fetch data from other three table by using
user_id employee_id service_id
employee table
employee_id pno name age pic_path
user table
user_id pno name age pic_path
service table
service_id name description
SELECT
t.*,
e.name AS employee_name,
u.name AS user_name,
s.name AS service_name, s.description
FROM tasks AS t
INNER JOIN employees AS e ON e.employee_id = t.employee_id
INNER JOIN users AS u ON u.user_id = t.user_id
INNER JOIN services AS s ON s.service_id = t.service_id
Related
I have two table one is accounts table and account group table. currently I am using the auto increment id as foreign key in the accounts table but my question is I have multiple tables where it will join with accounts table and I need to retrieve account group name in a view where there is 20 union all queries which it join to the accounts table.
SELECT acc.name,accgrp.groupName,bill.supplier,bill.amount
FROM bills bill
INNER JOIN accounts acc ON acc.accId=bills.accId
INNER JOIN accountGroup accgrp ON accgrp.groupId=acc.groupId
UNION ALL
.....
What is the correct way to save the data in accounts table saving id is the best approach or saving the group name is best approach. If i used id as foreign key and join in 20 union all is it make my query slower? or saving group name in my accounts table and retrieve it without join make my query faster?
I have 2 tables and need to make a View table
These are 2 tables that I have:
user table with some fields: id, username, email, pass
system_log table with 2 fields: uid, message (uid means user_id)
Now, I'd like to have a view table which gives me a table with 2 fields, username and message.
Here is my problem: I need username from user table in my view table while I have uid in my system_log table. Basically, instead of having uid, I need the username
The project and list of fields in the actual project are more than these but I just made it simple here to make my points clear.
You can use inner join to get the data from both tables
CREATE VIEW `view_name` AS
SELECT
u.user_name,
s.message
FROM users u
INNER JOIN system_log s ON u.id = s.user_id;
CREATE VIEW my_view AS
SELECT u.username, s.message FROM
user u INNER JOIN system_log s
ON u.id = s.user_id
I am just tinkering with SQL as I am trying to get into more complex statements. I don't know this qualifies for it or not but please guide how to go about it.
I have looked at JOINS and some question of Multiple Select Statements but unable to understand them correctly.
I have the following two tables:
emp table:
emp_id, name, address, org_id
books table:
id, emp_id, status, org_id
where emp_id in books table is foreign key referencing emp table.
I need to fetch all the records from books table of a particular org. But along with that I need to get all the data of respective employee like name, address along the result.
Please guide me in the right direction.
Thanks
Try this
select B.*,E.name,E.address from books B
inner join employee E
on B.emp_id=E.emp_id
where B.org_id=1;
I took value of of org_id as 1 for test purpose.
SELECT books.id, books.emp_id, books.status, books.org_id, emp.name, emp.address
FROM books
JOIN emp ON emp.emp_id = books.emp_id
WHERE books.org_id = '3'
As the other said, the org_id from emp table makes no sense. You must remove it from the table.
if you want all records from the books table try this
Select b.id,c.emp_id,b.status,e.name,e.address
from emp_table e
Left join books_table b
on(e.emp_id=b.emp_id)
where e.org_id='3' and b.org_id='3'
You can use this query this will gives you all book record with particular org_id along with all employee record
SELECT * FROM emp as e1
LEFT JOIN books as b1 ON e1.emp_id = b1.emp_id WHERE e1.org_id = 'YOUR_ID'
UNION ALL
SELECT * FROM emp as e1
RIGHT JOIN books as b1 ON e1.emp_id = b1.emp_id WHERE e1.org_id = 'YOUR_ID'
The following query should work for you:
SELECT b.id, b.status, b.org_id, e.emp_id, e.name, e.address
FROM Books b LEFT JOIN Employee e
ON e.emp_id = b.emp_id
WHERE b.org_id = 100
This would be the query for org 100.
It appears that your current schema is not normalized very well:
Employee: emp_id, name, address, org_id
Books: id, emp_id, status, org_id
The two tables both store the org_id, which presumably means the same thing.
This query might give you the results you want. You might want to learn more about joins in SQL. A LEFT JOIN gives you all records from one table, and matching records from another.
SELECT books.*,
emp.name AS emp_name,
emp.address AS emp_address,
emp.org_id AS emp_org_id
FROM books
LEFT JOIN emp ON books.emp_id = emp.emp_id
WHERE books.org_id=?
you can use this for all recors both tables :
select * from books
inner join emp on
books.emp_id=emp.emp_id
where books.emp_id=emp.emp_id
Okay, so I have two tables, a news table and a users table. They are set up as below:
news:
id title user_id contents
users:
id username password
When I run this query:
SELECT news.title, users.username, news.contents FROM news INNER JOIN users ON news.user_id=users.id WHERE news.id=:id
I can only access the user id using $query['id']. So it appears that the join is using the column names from table2, although I want them to map it to the column names of table1. So even though the column is called id in the users table, I want to access it under user_id, since I specified that in the JOIN query.
I need this because if I ever need the id from table1, they would both be mapped to the column called id and I would only be able to get the id of the users table.
So is there any way to do this? Access the column from table2 under the name of the column in table1?
In MySQL what you specify in the select statement is what it is called in the result set, so you need to tell it what to give you. you do that with the AS command
SELECT users.id AS user_id ... FROM ...
That way you can call it whatever you want
or grab the user_id from news with
SELECT news.user_id ... FROM ...
SELECT users.id AS id1, news.id AS id2, news.title, users.username, news.contents
FROM news INNER JOIN users ON news.user_id=users.id WHERE news.id=:id
echo $query['id1'] . $query['id2'];
I have a table of users, called ..wait for it... "users".. and then another table which records users' activity called ...you'll never guess... "activity"..
I have an HTML table which shows the users in the users table, but I want to order the table by the users' last activity.
Here's my query.
SELECT *
FROM `users`
JOIN `activity`
ON `activity`.`user_id` = `users`.`id`
ORDER BY `activity`.`timestamp`
LIMIT 25
The problem here is that it shows multiple rows for each user since there are multiple records for each user in the activity table.
How can I alter the query to only show one record for each user and order them by the last activity in the activity table.?
I did experiment with using the "DISTINCT" keyword but no luck :/
"one record for each user and order them by the last activity in the activity table.?"
Couly try this? Assuming you need both user info and activity info.
SELECT users.*, a.*
FROM users INNER JOIN (
SELECT user_id, MAX(timestamp) max_timestamp
FROM activity
GROUP BY user_id
) x ON users.user_id = x.user_id
INNER JOIN activity a ON x.user_id = a.user_id AND a.timestamp = x.max_timestamp
ORDER BY a.timestamp;
inner sub-query finds max_timestamp per user_id and outer JOIN finds activity has max_timestamp and user_id
This is not SQL solution, but what I would do is keep lastActivity column in Users table and update it when needed. Then sorting, filtering by this column would be very easy and efficient.