when I try to get results from 3 tables, I only get info from 2, the third one returns only NULL values.
This is my query, I am running it in phpmyAdmin to test it out before putting it on server:
SELECT uk2.*,u.*,COALESCE(SUM(n.cost),'not found') as cost
FROM std13_k2_users AS uk2
JOIN std13_users AS u
ON uk2.userID=u.id
JOIN std13_k2_naklady AS n
ON uk2.userID=n.userID WHERE uk2.userID=986
I get values from all tables when the SUM is not NULL (there are no things to sum in that table). When it is NULL I only get values from std13_users table. The values from std13_k2_users are NULL.
My question is: how should I repair my query? Thanks.
Try this please, assuming that your joins correctly done for your table schema.
SELECT uk2.*,u.*, case when SUM(COALESCE(n.cost,0)) = 0 then 'not found'
else SUM(COALESCE(n.cost,0)) end as cost
FROM std13_k2_users AS uk2
JOIN std13_users AS u
ON uk2.userID=u.id
JOIN std13_k2_naklady AS n
ON uk2.userID=n.userID WHERE uk2.userID=986
Related
This question already has answers here:
MySql Query Replace NULL with Empty String in Select
(10 answers)
Closed 4 months ago.
I am looking to replace the NULL values that occur as a result of a SQL JOIN statement, with 'N/A'.
I have tried to set the default value of both related columns from both tables to N/A, however, every time I execute the SQL JOIN statement, I still receive NULL values.
The two tables I have are the clients and Medical_Aid tables, which I have connected using a foreign key called Reg_No. Below is my sql join query
SELECT
clients.Id_Number,
clients.Medical_No,
medical_aid.Name AS Medical_Aid,
clients.First_Name,
clients.Last_Name,
clients.Age,
clients.Gender,
clients.Email,
clients.Telephone
FROM
clients
LEFT OUTER JOIN medical_aid ON clients.Reg_No = medical_aid.Reg_No;
I have tried to set the default value of the Medical_No and Medical_Name as 'N/A' but every time I execute a JOIN statement, NULL values are returned on the Medical_Name column only
Therefore, I am expecting the JOIN Statement to return 'N/A' for both the Medical_No and medical_AidName
SELECT
clients.Id_Number,
ISNULL(clients.Medical_No,'N/A'),
ISNULL(medical_aid.Name, 'N/A') AS Medical_Aid,
clients.First_Name,
clients.Last_Name,
clients.Age,
clients.Gender,
clients.Email,
clients.Telephone
FROM
clients
LEFT OUTER JOIN medical_aid ON clients.Reg_No = medical_aid.Reg_No;
For the values from the medial_aid table you can use the IsNull() function to replace a NULL with a different value:
IsNull(medical_aid.Name, 'N/A') AS Medical_Aid
If you want to also replace another field from the clients table when no record is found in the medical_aid table, you may need to use a CASE statement:
CASE WHEN medical_aid.Reg_No is null THEN 'N/A' else clients.Medical_No END AS Medical_No
This statement says that when medical_aid.Reg_No is NULL (since there was no record from the medical_aid found to join to the clients table) then output 'N/A', otherwise output clients.Medical_No.
I have a query that gets data and also joins another table (A) and counts the rows in that join table (B). However if the main table (A) is empty I want the query to return nothing. However it is returning a result of null for id and date and an integer value of 0 for users instead of a null row. How do I get an empty result instead of it returning something?
Returning:
id | date | users
null | null | 0
SQL Code
SELECT
`sessions`.`id`,
`sessions`.`date`,
COUNT( sessions_users.id ) AS users
FROM
`sessions`
LEFT JOIN `sessions_users` ON `sessions`.`id` = `sessions_users`.`sessions_id`
An aggregate query without a group by clause always returns a single record, regardless of the content of the underlying result set (and even if it is empty).
But, since you have non-aggregated columns in the select clause (sessions.id and sessions.date), your query is missing a group by clause anyway. In non-ancient versions in MySQL, where sql mode ONLY_FULL_GROUP_BY is enabled by default, this is a syntax error.
Consider:
SELECT
`sessions`.`id`,
`sessions`.`date`,
COUNT( sessions_users.id ) AS users
FROM
`sessions`
LEFT JOIN `sessions_users` ON `sessions`.`id` = `sessions_users`.`sessions_id`
GROUP BY
`sessions`.`id`,
`sessions`.`date`
This will produce one record per session id and date, along with the count of matching records in sessions_users. If there are no records in sessions, the query will return an empty result set.
If I understand correctly, instead of NULL, you want something like this:
id | date | users
| | 0
If so, just simply use IFNULL() in your SELECT as such:
SELECT
IFNULL(`sessions`.`id`,' ') as id,
IFNULL(`sessions`.`date`,' ') as date,
....
There are also a few other ways to achieve this using just IF() or CASE .. but IFNULL is very straight forward.
BUT if you don't want to see any NULL and 0 values, change your LEFT JOIN to INNER JOIN and you're done.
From your description, it sounds like you want an inner join:
SELECT s.id, s.date, COUNT(*) as users
FROM sessions s JOIN
sessions_users su
ON su.id = su.sessions_id;
I have 3 tables that I am using and need to make a query to return data from one table based on the value of a single column in the second table.
tbl_user
ID
login
pass
active
mscID
tbl_master
ID
name
training_date
MSCUnit
Active
tbl_msc
mscID
mscName
my current SQL statement:
SELECT
tbl_master.ID,
tbl_master.name,
tbl_master.training_date,
tbl_master.MSCUnit,
tbl_master.active,
tbl_user.mscID
FROM
tbl_master,
tbl_user
WHERE
tbl_master.active = 1 AND tbl_master.MSCUnit = tbl_user.mscID
The values stored in tbl_msc.mscID is a varchar(11) and it contains a string similar to A00 or A19. This is also the Primary key in the table.
The values stored in tbl_user.mscID matches that of tbl_msc.mscID. The values stored in tbl_master.UnitMSC also matches that of tbl_msc.mscID.
My goal is to return all records from tbl_master where the currently logged in user has the same mscID. The problem I am having is the statement returns all records in tbl_master.
I have tried several different join statements and for some reason, I cannot get this to filter correctly.
I am missing something. Any assistance in the SQL statement would be appreciated.
Thanks,
Will
You should be writing this using joins. I don't know how you know who the current user is, but the idea is to join the three tables together:
SELECT m.ID, m.name, m.training_date, m.MSCUnit, m.active,
u.mscID
FROM tbl_master m JOIN
tbl_user u
ON m.MSCUnit = u.mscID JOIN
tbl_msc msc
ON msc.mscID = u.msc_ID
WHERE m.active = 1 AND msc.mscName = ?;
Notice the use of proper, explicit, standard JOIN syntax and table aliases.
Select a.*, b.userid from
table_master a, table_user b where
a.mscunit in (select mscid from
table_user where active=1)
This should point you in the right direction.
The query below gives me 2 out of the 3 answers I'm looking for. On the sub-query select I get null instead of no
the 3 possible values for column name isCyl could be blank, yes, no
I'm not sure if the sub-query is the best way to go about it, but I don't know how else to re-state the query.
The schedule table has a series of columns to show what tasks must be completed on an assignment. Related tables store the results of the tasks if they were assigned to be completed. So I need to test if a specific task was scheduled. If so, then I need to see if the results of the task have been recorded in the related table. For brevity I am only showing one of the columns here.
SELECT s.`reckey`,
if(s.cylinders="T",
(select
if(c.areckey is not null,
"yes",
"no"
)
from cylinders c where c.areckey = s.reckey limit 1
)
,""
) as isCyl
from schedule s
where s.assignmentDate between 20161015 and 20161016
order by s.reckey
Use a LEFT JOIN, which returns NULL for columns in the child table when there's no match.
SELECT s.reckey, IF(s.cylinders = "T",
IF(c.areckey IS NOT NULL, 'yes', 'no'),
"") AS isCyl
FROM schedule AS s
LEFT JOIN cylinders AS c ON c.areckey = s.reckey
WHERE s.assignmentDate between 20161015 and 20161016
ORDER BY s.reckey
If there can be multiple rows in cylinders with the same areckey, change it to:
LEFT JOIN (select distinct areckey FROM cylinders) AS c on c.areckey = s.reckey
or use SELECT DISTINCT in the main query.
I am running into some trouble with the following circumstances:
I have a query that creates two temp tables, and the following select to join them together--
SELECT * FROM result
INNER JOIN result2 ON result2.packetDetailsId = result.packetDetailsId
I am then trying to create another column from concatenating a few of the resulting fields and then use that to reference/query against another table. Is there a way to accomplish this in one query? Should I get away from the temp tables?
Thank you again in advance.
update: If I try to alias the combination of the two temp tables I get an error message stating [Err] 1060 - Duplicate column name 'packetDetailsId'
select * from (
SELECT * FROM result
INNER JOIN result2 ON result2.packetDetailsId = result.packetDetailsId) as myalias
Another Update: I almost have it working as one query but I get the result "(BLOB)" in the column I concoctenated:
select packet_details.packetDetailsId,products.productId,Credit,AccountNum,OrderStat, CONCAT(products.productId,Credit,'_',OrderStat) as consol from (
select packetDetailsId, GROUP_CONCAT(Credit) AS Credit, GROUP_CONCAT(AccountNum) AS AccountNum, GROUP_CONCAT(OrderStat) AS OrderStat FROM
( SELECT pd_extrafields.packetDetailsId,
CASE WHEN pd_extrafields.ex_title LIKE ('%Credit%')
THEN pd_extrafields.ex_value ELSE NULL END as Credit,
CASE WHEN pd_extrafields.ex_title LIKE ('%Account%')
THEN pd_extrafields.ex_value ELSE NULL END as AccountNum,
CASE WHEN pd_extrafields.ex_title LIKE ('%Existing%')
THEN pd_extrafields.ex_value ELSE NULL END as OrderStat
FROM pd_extrafields )AS TempTab GROUP BY packetDetailsId ) as alias2
INNER JOIN packet_details ON alias2.packetDetailsId = packet_details.packetDetailsId
INNER JOIN sales ON packet_details.packetDetailsId = sales.packetDetailsId
INNER JOIN sold_products ON sales.saleId = sold_products.saleId
INNER JOIN products ON sold_products.productId = products.productId
If I understand correctly, you already have the temporary tables created and you need to "concatenate" the results, using from ... inner join ...
The only possible restriction you may have is that you can only reference your temporary tables once in your from clause; besides that, there are no other restrictions (I frequently use temporary tables as intermediate steps in the creation of my final result).
Tips
Let's say your temp tables are temp_result1 and temp_result2. Both tables have a field packedDetailsId, on which the join will be performed. Remember to create the appropriate indexes on each table; at the very least you need to index packedDetailsId on both tables:
alter table temp_result1
add index PDI(packedDetailsId);
alter table temp_result2
add index PDI(packedDetailsId);
Now, just execute a query with the desired join and concatenation. If concat returns BLOB, then cast the result as char (of course, I'm assuming you need a text string):
select r1.*, r2.*, cast(concat(r1.field1, ',', r2.field2) as char) as data_concat
from temp_result1 as r1
inner join temp_result2 as r2 on r1.packedDetailsId = r2.packedDetailsId;
I see your problem is that GROUP_CONCAT is returning BLOB values... It's normal (MySQL doesn't know a priori how to return the values, so it returns binary data); just use the cast function.
Hope this helps you
so, if the result2 and result are both temp tables, you will have to include the # if local temp table and ## if global temp table
so your statements should be :
SELECT * FROM #result
INNER JOIN #result2 ON #result2.packetDetailsId = #result.packetDetailsId
My Bad. This is only applicable for MS SQL