I have a problem with a query that I try to make over a table in database.
So my table has a column with names like this :
I want a query that will select names and ids in the following mode:
either
or
Thanks in advance...
You can use inner join and calc the id
#my_len = 3
select a.id as id, a.name as name, b.id as id1, b.name as name1, c.id as id2, c.name as name2
from my_table as a
inner join my_table as b where a.id = b.id+#my_len
inner join my_table as c where a.id = c.id+#my_len*2
Related
I am currently retrieving data from multiple tables using a cus_id as the initial query. From here I have multiple tables that can have various rows of data that I would like to retrieve and use GROUP_CONCAT to return this data in a single row. At the moment, my query is returning duplicate data based on the max number of rows returned by one of the group concats.
SELECT a.id,c.x,c.y,c.z
GROUP_CONCAT(a.column_a) AS aca,
GROUP_CONCAT(a.column_b) AS acb,
GROUP_CONCAT(b.column_a) AS bca,
GROUP_CONCAT(b.column_b) AS bcb,
FROM `table_a` a
INNER JOIN `table_b` b ON a.id = b.id
INNER JOIN `table_c` c ON a.id = c.id
WHERE a.id = ?
Also, in this scenario, what is the correct join method to use. I am expecting all the fields I am requesting to have some sort of data.
Problem was resolved by using sub queries to isolate the GROUP_CONCAT requests. This allowed me to get only the data I wanted without duplicate results manipulated by other JOIN requests.
SELECT a.id,c.x,c.y,c.z
(SELECT GROUP_CONCAT(column_a) FROM table_a) AS aca,
(SELECT GROUP_CONCAT(column_b) FROM table_a) AS acb,
(SELECT GROUP_CONCAT(column_a) FROM table_b) AS bca,
(SELECT GROUP_CONCAT(column_b) FROM table_b) AS bcb,
FROM table_a a
INNER JOIN `table_c` c ON a.id = c.id
WHERE a.id = ?
Aggregate before joining. Somthing along the lines of:
select
a.*,
b.grp_a,
b.grp_b,
c.grp_x,
b.grp_y
from table_a a
join
(
select
a_id,
group_concat(a order by b_id) as grp_a,
group_concat(b order by b_id) as grp_b
from table_b
group by a_id
) b on b.a_id = a.id
join
(
select
a_id,
group_concat(x order by c_id) as grp_x,
group_concat(y order by c_id) as grp_y
from table_c
group by a_id
) c on c.a_id = a.a_id
order by a.a_id;
I have this query:
select a.*, b.*, (select c.* from tableC c where c.id_tableA = a.id) from tableA a inner join tableB b on a.id = b.id_tableA where b.id_user = 50;
The subquery (which is tableC) is returning me more than 1 row as expected. How can I return only 1 row from tableC so it could match with the rest of the query?
So far I have tried this:
(select c.* from tableC c where c.id_tableA = a.id limit 1)
It didn't work as mysql said:
"Operand should contain 1 column(s)"
You are mixing two things. Scalar subquery in SELECT list should return only one value (both row and column). Using LIMIT 1 will get you one row, but still many columns.
So you could specify column name:
select a.*, b.*,
(select c.col_name from tableC c where c.id_tableA = a.id order by .. limit 1)
from tableA a
inner join tableB b on a.id = b.id_tableA
where b.id_user = 50;
or use normal JOIN:
select a.*, b.*, c.*
from tableA a
inner join tableB b
on a.id = b.id_tableA
left join tableC c
on c.id_tableA = a.id
where b.id_user = 50;
if column id from table C is a primary key then it should have no problem
but if no, try to add another condition that will filter your subquery results like ,
for example here is the start_date:
SELECT a.column_1, b.column_2,
(SELECT column_3 FROM tableC
WHERE (id = a.id
AND (start_date = (SELECT MAX(b.start_date)
from tableC as c
where a.id = c.id ))) AS column_3
FROM tableA as a INNER JOIN
tableB as b ON b.id = a.id
WHERE b.id_user = 50;
I have 2 tables in my SQL database. Let's call them Table A and Table B.
I have joined both the tables using left join on ID = AID. Table A has a field by name ID and Table B has field AID and Price.
The problem is Table B can have multiple prices for the ID present in Table A.
The requirement is - If only one price is present in Table B corresponding to ID in table A then it should return that price.
If more than one price is present in table B for an ID in table A then I should get the price as Zero/null.
Query -
SELECT DISTINCT A.ID,B.Price
from A
left join B
on A.ID = B.AID
where "some condition"
Use Count() with Over() window function to find the count of records for each ID then based on count return the price
Try this way
SELECT DISTINCT A.ID,
case when count(1) over(partition by A.ID) > 1 then NULL else B.Price end
from A
left join B
on A.ID = B.AID
For Mysql
SELECT DISTINCT a.id,
CASE
WHEN c.aid IS NULL THEN NULL
ELSE b.price
END
FROM a
LEFT JOIN b
ON a.id = b.aid
LEFT JOIN (SELECT aid
FROM b
GROUP BY aid
HAVING Count(1) = 1) c
ON a.id = c.aid
For SQL Server (should work for MySQL too). One sub-query (you can put in CTE) that shows only AIDs that have only one price:
SELECT A.ID,
B.Price
FROM A
LEFT JOIN (
SELECT AID
FROM B
GROUP BY AID
HAVING COUNT(Price) = 1
) as C
ON C.AID = A.ID
LEFT JOIN B
ON C.AID = B.AID
Use below query. It should work.
SELECT A.ID, o.Price
FROM A
OUTER APPLY
(
SELECT IIF(COUNT(B.Price)>1,NULL,MAX(B.Price)) AS Price
FROM B
WHERE B.AID = A.ID
) AS o;
How get a distinct value form more than one table (inner join query).
Eg,
select a.id,b.name,c.address
from table1 a
inner join table2 b on (a.id = b.row_id)
inner join table3 c on (a.id = c.ticket_id)
where c.status = 'open';
Here the scenario is for example, two rows contain the same a.id value so how to get the distinct value from a.id.
Somebody help me that how to get?
just add Distinct ...
select DISTINCT a.id,b.name,c.address
from table1 a
inner join table2 b on (a.id = b.row_id)
inner join table3 c on (a.id = c.ticket_id)
where c.status = 'open';
i think this is works fine..
if you need only one record distinct then it should be like this...
SELECT DISTINCT(cat_id) FROM PRODUCTS WHERE brand_id = 'sony'
ok so my problem is that I have a set of results:
ID CODE
1 A
1 B
3 C
I also have another table of:
CODE
A
B
C
What I want to get using SQL is a query of CODES that each result from table 1 is missing. So basically:
ID CODE
1 C
3 A
3 B
Any help would be great.
You can use:
SELECT a.id, b.code
FROM (SELECT DISTINCT id FROM idcodes) a
CROSS JOIN codes b
LEFT JOIN idcodes c ON a.id = c.id AND b.code = c.code
WHERE c.id IS NULL
ORDER BY a.id, b.code
If you have another table that stores unique entries for id, it would be better to just use that table instead rather than a DISTINCT subselect:
SELECT a.id, b.code
FROM ids a
CROSS JOIN codes b
LEFT JOIN idcodes c ON a.id = c.id AND b.code = c.code
WHERE c.id IS NULL
ORDER BY a.id, b.code
SQLFiddle Demo
You can use exists. Construct the full list of possible variations with a Cartesian join and then ensure what you have isn't in this list.
select id, code
from idcode_table x
where not exists ( select 1
from idcode_table a
cross join code_table b
where b.code = x.code
and a.id = x.id )
This can also be re-written with a not in.
select id, code
from idcode_table
where (id, code) not in ( select distinct a.id, b.code
from idcode_table a
cross join code_table b )
The distinct is optional. It will make it slower to construct the list of possibles but quicker to determine if you have one of them already. I'd test it to see which is quicker.