This query does not work:
WITH a AS
(SELECT 1 AS c1)
SELECT
*
FROM
a
UNION ALL
WITH b AS
(SELECT 1 AS c1)
SELECT
*
FROM
b
Could you help, please?
Real query uses tables, but it is not essential in the example.
Many thanks
;WITH a AS
(SELECT 1 AS c1),
b AS
(SELECT 1 AS c1)
SELECT
*
FROM
a
UNION ALL
SELECT
*
FROM
b
Simple answer: you're breaking the query ;-)
Let me explain:
The UNION key word takes 2 "queries" and makes them into one.
The WITH key word can't be used inside a query and it is only valid for one query
WITH can be used to define multiple CTEs
The result of all of these is that you want to define both of the CTEs (a & b) before the UNION query.
Putting the WITH inside the UNION query breaks the UNION (since WITH is always outside of (before) a query.
Related
I have a very simple select query which is being used to create an input file for a piece of software. I have the query pulling all the required fields, however I need to replicate the results six times with a hard coded ID number (1,2,3,4,5,6).
I have seen CROSS APPLY and PIVOT but the problem is the column I need to use for these doesn't exist as I'm hard coded then number.
Any help would be much appreciated.
Thanks in Advance
Maybe like this:
select CJ.ID,T.* from dbo.Table T
CROSS JOIN
(select 1 ID UNION ALL select 2 ID UNION ALL select 3 ID UNION ALL select 4 ID UNION ALL select 5 ID UNION ALL select 6 ID) CJ
Bit of a pure guess here, but are you saying that every row in your table needs to be repeated 6 times with the ID 1-6? If so, you can use a CTE of the values 1-6 and CROSS APPLY to that.
WITH Nums AS(
SELECT *
FROM (VALUES (1),(2),(3),(4),(5),(6)) V(N))
SELECT *
FROM YourTable YT
CROSS APPLY Nums;
I was recently asked this question and was a little stumped so I want to ask the experts...
Given two tables A & B, I want to return all the values from A and B that do not overlap. Think of two overlapping circles; how do we return all the data that is NOT in the overlapping center section? And, I had to use ANSI Standard SQL rather than Oracle syntax.
Assuming we want everything exclusive to both A & B, my answer was
select *
from A
cross join B
minus
(select a.common_column from a
intersect
select b.common_column)
Does this look correct, or even close? If it is correct, is there a more efficient way to do this?
BTW - my solution was soundly rejected....
Thank you!
Given the tables A and B, you are looking for (A U B) - (A & B). In other words, you need A union B minus their intersection. Remember A and B must be union-compatible for this query to work. I would do:
(select * from A
union
select * from B
)
minus
(select * from A
intersect
select * from B
)
May be full outer join?
select coalesce(A.col, B.col)
from A full outer join B on A.col = B.col
where A.col is null or B.col is null;
For computing a set symmetric difference, you can use a combination of MINUS and UNION ALL:
select * from (
(select * from A
minus
select * from B)
union all
(select * from B
minus
select * from A)
)
Your query was rejected because it is syntactically incorrect: the number of columns differ and it confuses cross join and union all. However, I think you have the right idea for solving this.
You can easily fix this:
(select *
from A
union all
select *
from B
) minus
(select *
from A
intersect
select *
from B
);
That is, combine everything using union all and then subtract the rows that occur in both tables.
Of course, if there is a single id, then you can use the id with join and other operations.
Just like Frank Schmitt answered in the meantime:
Here it is including a data example:
WITH
table_a(name) AS (
SELECT 'From_A_1'
UNION ALL SELECT 'From_A_2'
UNION ALL SELECT 'From_A_3'
UNION ALL SELECT 'From_A_4'
UNION ALL SELECT 'From_A_5'
UNION ALL SELECT 'From_BOTH_6'
UNION ALL SELECT 'From_BOTH_7'
UNION ALL SELECT 'From_BOTH_8'
)
,
table_b(name) AS (
SELECT 'From_B_1'
UNION ALL SELECT 'From_B_2'
UNION ALL SELECT 'From_B_3'
UNION ALL SELECT 'From_B_4'
UNION ALL SELECT 'From_B_5'
UNION ALL SELECT 'From_BOTH_6'
UNION ALL SELECT 'From_BOTH_7'
UNION ALL SELECT 'From_BOTH_8'
)
(SELECT * FROM table_a EXCEPT SELECT * FROM table_b)
UNION ALL
(SELECT * FROM table_b EXCEPT SELECT * FROM table_a)
ORDER BY name
;
name
From_A_1
From_A_2
From_A_3
From_A_4
From_A_5
From_B_1
From_B_2
From_B_3
From_B_4
From_B_5
You will need to select all the data from both tables, except where they overlap, and then combine the data with a union. The code provided should work for your example.
SELECT *
FROM
(
SELECT * FROM Table1
EXCEPT SELECT * FROM Table2
)
UNION
SELECT *
FROM
(
SELECT * FROM Table2
EXCEPT SELECT * FROM Table1
)
Hope this helps.
So, lets say I want to do something like:
SELECT Query1.a,
Query2.b
FROM (
SELECT q as a
FROM somewhere
),
(
SELECT g as b
FROM elsewhere
)
where Query 1 is
(
SELECT q as a
FROM somewhere
)
and Query2 is
(
SELECT g as b
FROM elsewhere
)
So, i want to select from two other select statements.
Query 1 produces a table
a
value1
Query 2 produces a table
b
value 2
And Query 3 (the outer select statement) produces
a b
value 1 value 2
So, essentially, two result tables are combined as columns and not as rows.
Thank you, if you have any hints.
You basically have your solution. You are only missing the names of your queries, so do like this:
SELECT Query1.a,
Query2.b
FROM (
SELECT q as a
FROM somewhere
) Query1,
(
SELECT g as b
FROM elsewhere
) Query2
It's not clear how you need to connect different rows from tables but it can be something like this:
select query1.a,
query2.b
FROM
(select q as a, ROW_NUMBER() OVER (ORDER BY q) as RN from a) Query1
FULL JOIN
(select q as b, ROW_NUMBER() OVER (ORDER BY q) as RN from b) Query2
ON Query1.RN=Query2.RN
SQLFiddle example
Your syntax is a bit off the SQL charts, but in essence ritgh:
It is possible to do a subquery:
select A.field from (select field from a_table) A;
It is essential that you name your query, if you want to use it in the select or where clauses.
And even possible to combine them like regular tables:
select A.field, B.other_field from (select field from table1) A, (select other_field from table2) B;
It is also possible to do al kind of where, grouping and sorting stuff on it, but not needed in your case.
I assume this is what you're looking for:
SELECT query1.a, query2.b
FROM
(SELECT q as a FROM somewhere) query1,
(SELECT g as b FROM elsewhere) query2
Here is a SQLFiddle to test the query
I would .like to perform a union of two queries where second query depends on first:
SELECT * FROM company_res t1
UNION
SELECT * FROM company_res t2
WHERE t2.company_id IN (
SELECT c.id
FROM company c
WHERE c.parent_id = t1.company_id
)
ORDER BY company_id, year_code
However, when I run this queries in psql I get an error to the effect that t1 in second query does have a FROM-clause.
Is it possible to have UNION of tow queries that depend on each other?
From your partial example I think you're trying to make a recursive query, and not a classical UNION query, that's an adavnced for of UNIONS if fact.
You need to perform some selections on company_res, and then to add parents of theses companies.
The basic form is:
WITH RECURSIVE t(n) AS (
SELECT 1
UNION ALL
SELECT n+1 FROM t
)
SELECT n FROM t LIMIT 100;
In you case something like that maybe:
WITH RECURSIVE rectable(
company_id,
field2,
field3,
parent_id) AS (
-- here the starting rows, t1 in your example
SELECT
company_res.company_id,
company_res.field2,
company_res.field3,
company.parent_id
FROM company_res
INNER JOIN company ON company_res.company_id=company.id
WHERE (here any condition on the starting points)
UNION ALL
-- here the recursive part
SELECT
orig.company_id,
orig.field2,
orig.field3,
orig.parent_id
FROM rectable rec,company_res orig
INNER JOIN company ON orig.company_id=company.id
WHERE company.parent_id=rec.company_id
-- here you could add some AND sections if you want
)
SELECT company_id,field2, field3,parent_id
FROM rectable
ORDER BY parent_id;
The SELECT * FROM company_res t1 in your query is going to provide you with everything from company_res, regardless of what else you UNION it with from company_res. I doubt that's what you're looking for. See the answer from shahkalpesh.
SELECT *
FROM
(SELECT Campus_ID AS A_Campus, * FROM A_Campuses
UNION
SELECT Campus_ID AS H_Campus, * FROM H_Campuses
UNION
SELECT Campus_ID AS B_Campus, * FROM B_Campuses)
ORDER BY Campus_Name ASC
It gives the sql error
#1064 - You have an error in your SQL syntax; check the manual that
corresponds to your MySQL server
version for the right syntax to use
near '* FROM A_Campuses UNION
SELECT Campus_ID AS H_Campus, * FROM
H_Campuses' at line 3
Step 1
You have two syntax errors
not aliasing the derived table.
* cannot be used AFTER a column name, unless you alias the source table
SELECT *
FROM
(SELECT Campus_ID AS A_Campus, A.* FROM A_Campuses A
UNION
SELECT Campus_ID AS H_Campus, H.* FROM H_Campuses H
UNION
SELECT Campus_ID AS B_Campus, B.* FROM B_Campuses B) AS X
ORDER BY Campus_Name ASC
Step 2
But as Phil points out, since you are sub-querying only to do an order by, there is no need to subquery at all. ORDER BY applies to the entire UNION-ed result.
SELECT Campus_ID AS A_Campus, A.* FROM A_Campuses A
UNION
SELECT Campus_ID AS H_Campus, H.* FROM H_Campuses H
UNION
SELECT Campus_ID AS B_Campus, B.* FROM B_Campuses B
ORDER BY Campus_Name ASC
Step 3
The next thing to point out is that A_, H_ and B_ must ALL have compatible structures for the UNION to align properly. It is also worth mentioning that aliasing Campus_ID as different column names has no value. The column names of the resultant result of a UNION is the FIRST name encountered across the UNION parts - in this case all the column names will come from A_Campuses, as well as the additional column A_Campus. In actual fact, you will have two columns A_Campus and Campus_ID which will always hold EXACTLY the same values. What you probably wanted was to indicate the SOURCE of the data: (notice that I have not even bothered to alias the columns for the 2nd and 3rd parts of the UNION)
SELECT 'A' AS Source, A.* FROM A_Campuses A
UNION ALL
SELECT 'H', H.* FROM H_Campuses H
UNION ALL
SELECT 'B', B.* FROM B_Campuses B
ORDER BY Campus_Name ASC
Note
For performance reasons, use UNION ALL instead of UNION, which performs a DISTINCT against the final result. If you had duplicate Campus_ID across different tables, as well as exactly the same record data, UNION results in one of them being removed, whereas UNION ALL keeps both (or all 3) copies. Given the addition of the Source column, this is not a possibility, so using UNION ALL will result in a faster query.
The columns in each branch of the UNION normally need the same name, or will end up with a single name. Also, a sub-select needs an alias (the 'AS C' below), at least in standard SQL; even if you don't mention the alias anywhere else in the query, as below.
I think what you're after is likely:
SELECT *
FROM (SELECT "A" AS Campus_ID, * FROM A_Campuses
UNION
SELECT "H" AS Campus_ID, * FROM H_Campuses
UNION
SELECT "B" AS Campus_ID, * FROM B_Campuses) AS C
ORDER BY Campus_Name ASC
That isn't how you write a union query.
Any ORDER BY clause applies to the union so you don't need to sub-query it. Also, you should aim to have the same column names and aliases across all parts of the union. Your A_Campus, H_Campus and B_Campus aliases will be lost (not sure which one will win out). For example
SELECT Campus_ID, Campus_Name FROM A_Campuses
UNION
SELECT Campus_ID, Campus_Name FROM H_Campuses
UNION
SELECT Campus_ID, Campus_Name FROM B_Campuses
ORDER BY Campus_Name ASC
I'd also refrain from using SELECT * in a union as you need to be specific about what you're selecting.
perhaps more parenthesis are needed
SELECT *
FROM
(
(SELECT Campus_ID AS A_Campus, * FROM A_Campuses)
UNION
(SELECT Campus_ID AS H_Campus, * FROM H_Campuses)
UNION
(SELECT Campus_ID AS B_Campus, * FROM B_Campuses)
)
ORDER BY Campus_Name ASC
Also can you UNION with different column names like that? You might need a fake A_Campus and B_Campus in the H_Campus subquery to get identical columns.