I'm trying to join two MySQL Tables to get a staffid from one and a username that is tied to the staffid in another table so that I just have the username displayed
SELECT ost_ticket.staff_id, count(*) as numbers
FROM ost_ticket AS us
JOIN ost_staff AS re
ON re.username = us.userid
GROUP BY ost_ticket.staff_id;
From what I've been reading about joins this should work?
EDIT: I've ran it and I get unknown column 'ost_ticket.staff_id' in field list
You've aliased the two tables (as re and us), so you'll need to use the aliases. Also, it seems you've joined to the ost_staff table to retrieve the username, so if you want to display the user name, you need to select + group by it, and not the staff_id column.
SELECT re.username, count(*) as numbers
FROM ost_ticket AS us
JOIN ost_staff AS re
ON re.userid = us.userid
GROUP BY re.username;
(substitute your actual PK for ost_staff - I've assumed userid)
SELECT us.staff_id, re.username, count(*) as numbers
FROM ost_ticket AS us
JOIN ost_staff AS re
ON re.userid= us.staff_id
GROUP BY us.staff_id;
Related
I have two tables. One for Customer and other is for managing login history. Now what I want to do is to get the customer name and email from customer table, and last login time from loghistory table.
I have used the query:
select cust_email, login_time, cust_email
from customer
left join login on customer.cust_id = login.cust_id
GROUP by cust_id
It gives me the correct result showing NULL for the customers who never logged in, but gives the first login time of other customers not the latest one. How do I get the last login time of customer?
Use MAX() & columns which are in SELECT statement must be aggregated or it should be with GROUP BY clause :
select c.cust_email, max(l.login_time)
from customer c left join
login l
on c.cust_id = l.cust_id
GROUP BY c.cust_email;
Note : Use table alias that is easy to understand & read.
use max() function
select cust_email,max(login_time) as max_login_time from customer
left join login on customer.cust_id=login.cust_id
GROUP by cust_email
I think you should use simple "Join" not left join with a order by clause. Try this:
select cust_email, login_time, cust_email
from customer
join login on customer.cust_id = login.cust_id
GROUP by cust_id
Order by login_time esc
I have two tables (user and I_S) and the I_S table contains a column called score. I need to obtain the highest score and the corresponding user name from the tables.
I used a left join but I keep getting an error saying
Unknown column 'I_S.total_score' in 'field list'
This is the query I used.
SELECT MAX(interview_sessions.total_score)
FROM interview_sessions as sc
LEFT JOIN user as u on sc.user_id = u.user_id
SELECT DISTINCT users.name, I_S.score FROM users
LEFT JOIN I_S ON I_S.user_id = users.user_id WHERE score IN (SELECT MAX(score) FROM I_S)
All users with Max score.
And i think you should write sc.total_score instead interview_sessions.total_score in your query because you use alias
Try using this:
SELECT MAX(sc.total_score)
FROM interview_sessions as sc
LEFT JOIN user as u on sc.user_id = u.user_id
You need an inner query to first determine WHAT is the highest score. Form that, re-join to the interview sessions table on THAT max score. Then join to users to get the names. It is possible multiple people can have a same max score.
select
from
( SELECT MAX(i_s.total_score) as MaxScore
from interview_sessions i_s ) maxAll
JOIN interview_sessions i_s2
on maxAll.MaxScore = i_s2.total_score
JOIN User u
on i_s2.user_id = u.user_id
try this way
select b.*,a.totalscore from user b
inner join( select userid,max(total_score) as totalscore from I_S) a on a.userid=b.userid
I'm trying to get a list of the number of entries in the changes_cc table by each user. Not all users have made entries into it, however for some reason it's returning "1" for each user that has 0 entries. I'm assuming that it's because it's counting the entries in the JOINed table. How can I make it so that it is "0" instead?
SELECT COUNT(*) as num, users.id, realname, username
FROM changes_cc
RIGHT JOIN users
ON changes_cc.user_id = users.id
GROUP BY users.id
I think this should work -- count a specific field in the changes_cc table vs counting *:
SELECT u.id, realname, username, COUNT(c.id) as num
FROM users u
LEFT JOIN changes_cc c
ON u.user_id = c.id
GROUP BY u.id
I prefer reading a LEFT JOIN over a RIGHT JOIN, but they are both OUTER JOINs and work the same.
You should not be using COUNT(*) (counts the record including null values) because it will normally give atleast 1 since it returns all records from the right table. If you specify the column name to be counted, it will gove you the result you want because COUNT only counts for NON_NULL value.
SELECT COUNT(changes_cc.user_id) as num,
users.id,
realname,
username
FROM changes_cc
RIGHT JOIN users
ON changes_cc.user_id = users.id
GROUP BY users.id
Instead of using count(*), use count(changes_cc.user_id).
The problem is that you are counting rows (with the *) rather than counting the non-NULL values in the "right-joined" table.
I have a user table from which I want all values, so I have this query:
SELECT tbl_user.* FROM tbl_user
Now I want one additional column in this result which shows all roles this user has, (or nothing if there are no roles for the user). The role information comes from two additional tables.
The first table contains these two values: userid, roleid
The second table contains roleid and role_name.
So the group concat needs to get all role names based on the roleid's in table1.
I have tried several different ways to do this, but I don't succeed. Either I get only one result with several times the same rolename, or no result at all.
Thanks for your help
Michael
Update: added LEFT JOIN for users with no role.
SELECT
tbl_user.*,
GROUP_CONCAT(role_name) AS roles
FROM
tbl_user LEFT JOIN tbl_roles ON tbl_user.userid = tbl_roles.userid
JOIN tbl_rolenames ON tbl_roles.roleid = tbl_rolenames.roleid
GROUP BY tbl_user.userid
Note that MySQL will permit a GROUP BY on fewer columns than appear in the SELECT list in total, but in other RDBMS you would need to explicitly list out the columns in tbl_user and include them in the GROUP BY, or do an additional self join against tbl_user to get the remaining columns from that table.
Something like:
SELECT
urole.userid,
uall.username,
uall.name,
uall.othercols,
urole.roles
FROM
tbl_user uall JOIN (
SELECT
tbl_user.userid,
GROUP_CONCAT(role_name) AS roles
FROM
tbl_user LEFT JOIN tbl_roles ON tbl_user.userid = tbl_roles.roleid
JOIN tbl_rolenames ON tbl_roles.roleid = tbl_rolenames.roleid
GROUP BY tbl_user.userid
) urole ON uall.userid = urole.userid
I have a table for referred users (contains an email address and date columns) and a table for users.
I run to get the top referers:
SELECT count(r.Email) as count, r.Email
FROM refs r
WHERE r.referredOn > '2011-12-13'
GROUP BY email
ORDER BY count DESC
But I want to join this with the users table so it displays with other data in the user table, I thought a join would work. Left join becuase emails may be entered incorrectly, some people put first name etc under refs.Email
SELECT count(r.Email) as count, r.Email, u.*
FROM refs r LEFT JOIN users u ON u.email_primary = r.Email
WHERE r.referredOn > '2011-12-13'
GROUP BY email
ORDER BY count DESC
With the above query the count is incorrect, but I don't know why.
Try this one:
SELECT count(r.Email) as count, r.Email
FROM refs r
INNER JOIN users u ON u.email_primary = r.Email
WHERE r.referredOn > '2011-12-13'
GROUP BY email
ORDER BY count DESC
if your adding new column from users u you also need to add it on your group by clause.
Regards
Unfortunately, a LEFT JOIN wont help you here; what this type of join says is give me all the rows in users that match my email, as well as all the rows that have no match on email. If the email doesn't match, then they wont come back as you want.
So you can't use a the left join condition here the way you want.
If you enforced the fact that they had to enter an email everytime, and it was a valid email etc, then you could use an INNER JOIN.
JOINs are usually used to follow referential integrity. So, for example, I have a user with an id in one table, and another table with the column userid - there is a strong relationship between the two tables I can join on.
Jeft Atwood has a good explantion of how joins work.
SEE if this will help you:
SELECT e.count, e.email, u.col1, u.col2 -- etc
FROM (
SELECT count(r.Email) as count, r.Email
FROM refs r
WHERE r.referredOn > '2011-12-13'
GROUP BY email
) e
INNER JOIN
users u ON u.email_primary = e.Email
Instead of a direct join, you could TRY to use your counting query as a subquery-table type..
I wrote this query
SELECT *, count(r.Email) as count FROM refs r
LEFT OUTER JOIN users u ON r.email = u.email_primary
WHERE u.uid IS NOT NULL
GROUP BY u.uid
ORDER BY count DESC
Which showed me that the reason the count was wrong was because some of the email addresses are used twice in the users table (users sharing 'family' email address), this doubled my count, the above query shows each separate user account.