Related
i am trying to replicate below scenario using oracle sql query:
i have did it using union query , but in that query i am hitting same table multiple times, is there any alternate for this query?
Please note: col and val are depenedent on each other simillarly col_1 and val_1 are also dependent on each other
select id,col, val from tbl
union
select id,col_1, val_1 from tbl
Oracle 12C+ supports lateral joins, so you can do:
select t.id, v.col, v.val
from tbl t cross join lateral
(select t.col, t.val from dual union all
select t.col_1, t.val from dual
) v;
You can pivot and unpivot multiple columns with the PIVOT and UNPIVOT operators, you just need to know the correct syntax. In your case you want to UNPIVOT. You are losing some information in the way you show the desired output, and perhaps that's OK for your needs; in any case, below I include a column that shows the order of the pairs of columns. (A bit odd, showing 1 for COL/VAL and 2 for COL_1/VAL_1, but I assume those aren't your real column names anyway.) If you don't need the ORD column in the output, just drop it from the SELECT clause.
Note - COLUMN is an Oracle reserved word, it can't be a column name. I changed the column names to C and V in the output.
with
input(id, col, col_1, val, val_1) as (
select 1, 'ABC', 'DEF', 10, 20 from dual union all
select 2, 'GHI', 'JKL', 30, 40 from dual
)
select id, ord, c, v
from input
unpivot ( (c, v) for ord in ((col, val) as 1, (col_1, val_1) as 2))
;
ID ORD C V
---------- ---------- --- ----------
1 1 ABC 10
1 2 DEF 20
2 1 GHI 30
2 2 JKL 40
I have almost the same problem as described in this question. I have two tables with the same number of rows, and I would like to join them together one by one.
The tables are ordered, and I would like to keep this order after the join, if it is possible.
There is a rowid based solution for MSSql, but in SQLite rowid can not be used if the table is coming from a WITH statement (or RECURSIVE WITH).
It is guaranteed that the two tables have the exact same number of rows, but this number is not known beforehand. It is also important to note, that the same element may occur more than twice. The results are ordered, but none of the columns are unique.
Example code:
WITH
table_a (n) AS (
SELECT 2
UNION ALL
SELECT 4
UNION ALL
SELECT 5
),
table_b (s) AS (
SELECT 'valuex'
UNION ALL
SELECT 'valuey'
UNION ALL
SELECT 'valuez'
)
SELECT table_a.n, table_b.s
FROM table_a
LEFT JOIN table_b ON ( table_a.rowid = table_b.rowid )
The result I would like to achieve is:
(2, 'valuex'),
(4, 'valuey'),
(5, 'valuez')
SQLFiddle: http://sqlfiddle.com/#!5/9eecb7/6888
This is quite complicated in SQLite -- because you are allowing duplicates. But you can do it. Here is the idea:
Summarize the table by the values.
For each value, get the count and offset from the beginning of the values.
Then use a join to associate the values and figure out the overlap.
Finally use a recursive CTE to extract the values that you want.
The following code assumes that n and s are ordered -- as you specify in your question. However, it would work (with small modifications) if another column specified the ordering.
You will notice that I have included duplicates in the sample data:
WITH table_a (n) AS (
SELECT 2 UNION ALL
SELECT 4 UNION ALL
SELECT 4 UNION ALL
SELECT 4 UNION ALL
SELECT 5
),
table_b (s) AS (
SELECT 'valuex' UNION ALL
SELECT 'valuey' UNION ALL
SELECT 'valuey' UNION ALL
SELECT 'valuez' UNION ALL
SELECT 'valuez'
),
a as (
select a.n, count(*) as a_cnt,
(select count(*) from table_a a2 where a2.n < a.n) as a_offset
from table_a a
group by a.n
),
b as (
select b.s, count(*) as b_cnt,
(select count(*) from table_b b2 where b2.s < b.s) as b_offset
from table_b b
group by b.s
),
ab as (
select a.*, b.*,
max(a.a_offset, b.b_offset) as offset,
min(a.a_offset + a.a_cnt, b.b_offset + b.b_cnt) - max(a.a_offset, b.b_offset) as cnt
from a join
b
on a.a_offset + a.a_cnt - 1 >= b.b_offset and
a.a_offset <= b.b_offset + b.b_cnt - 1
),
cte as (
select n, s, offset, cnt, 1 as ind
from ab
union all
select n, s, offset, cnt, ind + 1
from cte
where ind < cnt
)
select n, s
from cte
order by n, s;
Here is a DB Fiddle showing the results.
I should note that this would be much simpler in almost any other database, using window functions (or perhaps variables in MySQL).
Since the tables are ordered, you can add row_id values by comparing n values.
But still the best way in order to get better performance would be inserting the ID values while creating the tables.
http://sqlfiddle.com/#!5/9eecb7/7014
WITH
table_a_a (n, id) AS
(
WITH table_a (n) AS
(
SELECT 2
UNION ALL
SELECT 4
UNION ALL
SELECT 5
)
SELECT table_a.n, (select count(1) from table_a b where b.n <= table_a.n) id
FROM table_a
) ,
table_b_b (n, id) AS
(
WITH table_a (n) AS
(
SELECT 'valuex'
UNION ALL
SELECT 'valuey'
UNION ALL
SELECT 'valuez'
)
SELECT table_a.n, (select count(1) from table_a b where b.n <= table_a.n) id
FROM table_a
)
select table_a_a.n,table_b_b.n from table_a_a,table_b_b where table_a_a.ID = table_b_b.ID
or convert the input set to comma separated list and try like this:
http://sqlfiddle.com/#!5/9eecb7/7337
WITH RECURSIVE table_b( id,element, remainder ) AS (
SELECT 0,NULL AS element, 'valuex,valuey,valuz,valuz' AS remainder
UNION ALL
SELECT id+1,
CASE
WHEN INSTR( remainder, ',' )>0 THEN
SUBSTR( remainder, 0, INSTR( remainder, ',' ) )
ELSE
remainder
END AS element,
CASE
WHEN INSTR( remainder, ',' )>0 THEN
SUBSTR( remainder, INSTR( remainder, ',' )+1 )
ELSE
NULL
END AS remainder
FROM table_b
WHERE remainder IS NOT NULL
),
table_a( id,element, remainder ) AS (
SELECT 0,NULL AS element, '2,4,5,7' AS remainder
UNION ALL
SELECT id+1,
CASE
WHEN INSTR( remainder, ',' )>0 THEN
SUBSTR( remainder, 0, INSTR( remainder, ',' ) )
ELSE
remainder
END AS element,
CASE
WHEN INSTR( remainder, ',' )>0 THEN
SUBSTR( remainder, INSTR( remainder, ',' )+1 )
ELSE
NULL
END AS remainder
FROM table_a
WHERE remainder IS NOT NULL
)
SELECT table_b.element, table_a.element FROM table_b, table_a WHERE table_a.element IS NOT NULL and table_a.id = table_b.id;
SQL
SELECT a1.n, b1.s
FROM table_a a1
LEFT JOIN table_b b1
ON (SELECT COUNT(*) FROM table_a a2 WHERE a2.n <= a1.n) =
(SELECT COUNT(*) FROM table_b b2 WHERE b2.s <= b1.s)
Explanation
The query simply counts the number of rows up until the current one for each table (based on the ordering column) and joins on this value.
Demo
See SQL Fiddle demo.
Assumptions
A single column in used for the ordering in each table. (But the query could easily be modified to allow multiple ordering columns).
The ordering values in each table are unique.
The values in the ordering column aren't necessarily the same between the two tables.
It is known that table_a contains either the same or more rows than table_b. (If this isn't the case then a FULL OUTER JOIN would need to be emulated since SQLite doesn't provide one.)
No further changes to the table structure are allowed. (If they are, it would be more efficient to have pre-populated columns for the ordering).
Either way...
Use something like
WITH
v_table_a (n, rowid) AS (
SELECT 2, 1
UNION ALL
SELECT 4, 2
UNION ALL
SELECT 5, 3
),
v_table_b (s, rowid) AS (
SELECT 'valuex', 1
UNION ALL
SELECT 'valuey', 2
UNION ALL
SELECT 'valuez', 3
)
SELECT v_table_a.n, v_table_b.s
FROM v_table_a
LEFT JOIN v_table_b ON ( v_table_a.rowid = v_table_b.rowid );
for "virtual" tables (with WITH or without),
WITH RECURSIVE vr_table_a (n, rowid) AS (
VALUES (2, 1)
UNION ALL
SELECT n + 2, rowid + 1 FROM vr_table_a WHERE rowid < 3
)
, vr_table_b (s, rowid) AS (
VALUES ('I', 1)
UNION ALL
SELECT s || 'I', rowid + 1 FROM vr_table_b WHERE rowid < 3
)
SELECT vr_table_a.n, vr_table_b.s
FROM vr_table_a
LEFT JOIN vr_table_b ON ( vr_table_a.rowid = vr_table_b.rowid );
for "virtual" tables using recursive WITHs (in this example the values are others then yours, but I guess you get the point) and
CREATE TABLE p_table_a (n INT);
INSERT INTO p_table_a VALUES (2), (4), (5);
CREATE TABLE p_table_b (s VARCHAR(6));
INSERT INTO p_table_b VALUES ('valuex'), ('valuey'), ('valuez');
SELECT p_table_a.n, p_table_b.s
FROM p_table_a
LEFT JOIN p_table_b ON ( p_table_a.rowid = p_table_b.rowid );
for physical tables.
I'd be careful with the last one though. A quick test shows, that the numbers of rowid are a) reused -- when some rows are deleted and others are inserted, the inserted rows get the rowids from the old rows (i.e. rowid in SQLite isn't unique past the lifetime of a row, whereas e.g. Oracle's rowid AFAIR is) -- and b) corresponds to the order of insertion. But I don't know and didn't find a clue in the documentation, if that's guaranteed or is subject to change in other/future implementations. Or maybe it's just a mere coincidence in my test environment.
(In general physical order of rows may be subject to change (even within the same database using the same DMBS as a result of some reorganization) and is therefore no good choice to rely on. And it's not guaranteed, a query will return the result ordered by physical position in the table as well (it might use the order of some index instead or have a partial result ordered some other way influencing the output's order). Consider designing your tables using common (sort) keys in corresponding rows for ordering and to join on.)
You can create temp tables to carry CTE data row. then JOIN them by sqlite row_id column.
CREATE TEMP TABLE temp_a(n integer);
CREATE TEMP TABLE temp_b(n VARCHAR(255));
WITH table_a(n) AS (
SELECT 2 n
UNION ALL
SELECT 4
UNION ALL
SELECT 5
UNION ALL
SELECT 5
)
INSERT INTO temp_a (n) SELECT n FROM table_a;
WITH table_b (n) AS
(
SELECT 'valuex'
UNION ALL
SELECT 'valuey'
UNION ALL
SELECT 'valuez'
UNION ALL
SELECT 'valuew'
)
INSERT INTO temp_b (n) SELECT n FROM table_b;
SELECT *
FROM temp_a a
INNER JOIN temp_b b on a.rowid = b.rowid;
sqlfiddle:http://sqlfiddle.com/#!5/9eecb7/7252
It is possible to use the rowid inside a with statement but you need to select it and make it available to the query using it.
Something like this:
with tablea AS (
select id, rowid AS rid from someids),
tableb AS (
select details, rowid AS rid from somedetails)
select tablea.id, tableb.details
from
tablea
left join tableb on tablea.rid = tableb.rid;
It is however as they have already warned you a really bad idea. What if the app breaks after inserting in one table but before the other one? What if you delete an old row? If you want to join two tables you need to specify the field to do so. There are so many things that could go wrong with this design. The most similar thing to this would be an incremental id field that you would save in the table and use in your application. Even simpler, make those into one table.
Read this link for more information about the rowid: https://www.sqlite.org/lang_createtable.html#rowid
sqlfiddle: http://sqlfiddle.com/#!7/29fd8/1
It is possible to use the rowid inside a with statement but you need to select it and make it available to the query using it. Something like this:
with tablea AS (select id, rowid AS rid from someids),
tableb AS (select details, rowid AS rid from somedetails)
select tablea.id, tableb.details
from
tablea
left join tableb on tablea.rid = tableb.rid;
The problem statement indicates:
The tables are ordered
If this means that the ordering is defined by the ordering of the values in the UNION ALL statements, and if SQLite respects that ordering, then the following solution may be of interest because, apart from small tweaks to the last three lines of the sample program, it adds just two lines:
A(rid,n) AS (SELECT ROW_NUMBER() OVER ( ORDER BY 1 ) rid, n FROM table_a),
B(rid,s) AS (SELECT ROW_NUMBER() OVER ( ORDER BY 1 ) rid, s FROM table_b)
That is, table A is table_a augmented with a rowid, and similarly for table B.
Unfortunately, there is a caveat, though it might just be the result of my not having found the relevant specifications. Before delving into that, however, here is the full proposed solution:
WITH
table_a (n) AS (
SELECT 2
UNION ALL
SELECT 4
UNION ALL
SELECT 5
),
table_b (s) AS (
SELECT 'valuex'
UNION ALL
SELECT 'valuey'
UNION ALL
SELECT 'valuez'
),
A(rid,n) AS (SELECT ROW_NUMBER() OVER ( ORDER BY 1 ) rid, n FROM table_a),
B(rid,s) AS (SELECT ROW_NUMBER() OVER ( ORDER BY 1 ) rid, s FROM table_b)
SELECT A.n, B.s
FROM A LEFT JOIN B
ON ( A.rid = B.rid );
Caveat
The proposed solution has been tested against a variety of data sets using sqlite version 3.29.0, but whether or not it is, and will continue to be, "guaranteed" to work is unclear to me.
Of course, if SQLite offers no guarantees with respect to the ordering of the UNION ALL statements (that is, if the question is based on an incorrect assumption), then it would be interesting to see a well-founded reformulation.
I have the following table structure
start|end
09:00|11:00
13:00|14:00
I know
SELECT ARRAY_AGG(start), ARRAY_AGG(end)
Will result in
start|end
[09:00,13:00]|[11:00,14:00]
But how can i get the following result?
result
[09:00,11:00,13:00,14:00]
BTW, I'm using Postgres
You could do array concatenation (if order is not important):
SELECT ARRAY_AGG(start) || ARRAY_AGG(end) FROM TABLE1
If order is important you could use Gordon's approach but:
add aggregate order array_agg(d order by d ASC)
use unnest instead of union all, because Gordon's solution (union all) performs two sequence scan. If table is big it could be better for performance to use:
SELECT array_agg(d ORDER BY d ASC) FROM(
SELECT unnest(ARRAY[start] || ARRAY[end]) as d from table1
) sub
which performs only one sequence scan on table (and will be faster).
One method is to unpivot them and then aggregate:
select array_agg(d)
from (select start as d from t
union all
select end as d from t
) t;
A similar method uses a cross join:
select array_agg(case when n.n = 1 then t.start else t.end end)
from t cross join
(select 1 as n union all select 2) n;
I assume the start and end are character type
select ARRAY_AGG(col)
from(select string_agg(strt::text||','||en::text,',') col
from b
)t
When two sets are given
s1 ={ a,b,c,d} s2={b,c,d,a}
(i.e)
TableA
Item
a
b
c
d
TableB
Item
b
c
d
a
How to write Sql query to display "Elements in tableA and tableB are equal". [Without using SP or UDF]
Output
Elements in TableA and TableB contains identical sets
Use:
SELECT CASE
WHEN COUNT(*) = (SELECT COUNT(*) FROM a)
AND COUNT(*) = (SELECT COUNT(*) FROM b) THEN 'Elements in TableA and TableB contains identical sets'
ELSE 'TableA and TableB do NOT contain identical sets'
END
FROM (SELECT a.col
FROM a
INTERSECT
SELECT b.col
FROM b) x
Test with:
WITH a AS (
SELECT 'a' AS col
UNION ALL
SELECT 'b'
UNION ALL
SELECT 'c'
UNION ALL
SELECT 'd'),
b AS (
SELECT 'b' AS col
UNION ALL
SELECT 'c'
UNION ALL
SELECT 'd'
UNION ALL
SELECT 'a')
SELECT CASE
WHEN COUNT(*) = (SELECT COUNT(*) FROM a)
AND COUNT(*) = (SELECT COUNT(*) FROM b) THEN 'yes'
ELSE 'no'
END
FROM (SELECT a.col
FROM a
INTERSECT
SELECT b.col
FROM b) x
Something like this, using FULL JOIN:
SELECT
CASE
WHEN EXISTS (
SELECT * FROM s1 FULL JOIN s2 ON s1.Item = s2.Item
WHERE s1.Item IS NULL OR s2.Item IS NULL
)
THEN 'Elements in tableA and tableB are not equal'
ELSE 'Elements in tableA and tableB are equal'
END
This has the virtue of short-circuiting on the first non-match, unlike other solutions that require 2 full scans of each table (once for the COUNT(*), once for the JOIN/INTERSECT).
Estimated cost is significantly less than other solutions.
Watch out, I'm gonna use a Cross Join.
Declare #t1 table(val varchar(20))
Declare #t2 table(val varchar(20))
insert into #t1 values ('a')
insert into #t1 values ('b')
insert into #t1 values ('c')
insert into #t1 values ('d')
insert into #t2 values ('c')
insert into #t2 values ('d')
insert into #t2 values ('b')
insert into #t2 values ('a')
select
case when
count(1) =
(((Select count(1) from #t1)
+ (Select count(1) from #t2)) / 2.0)
then 1 else 0 end as SetsMatch from
#t1 t1 cross join #t2 t2
where t1.val = t2.val
My monstrocity:
;with SetA as
(select 'a' c union
select 'b' union
select 'c')
, SetB as
(select 'b' c union
select 'c' union
select 'a' union
select 'd'
)
select case (select count(*) from (
select * from SetA except select * from SetB
union
select * from SetB except select * from SetA
)t)
when 0 then 'Equal' else 'NotEqual' end 'Equality'
Could do it with EXCEPT and a case
select
case
when count (1)=0
then 'Elements in TableA and TableB contains identical sets'
else 'Nope' end from (
select item from s1
EXCEPT
select item from s2
) b
Since this thread was very helpful to me, I thought I'd share my solution.
I had a similar problem, perhaps more generally applicable than this specific single-set comparison. I was trying to find the id of an element that had a set of multi-element child elements that matched a query set of multi-element items.
The relevant schema information is:
table events, pk id
table solutions, pk id, fk event_id -> events
table solution_sources, fk solutionid -> solutions
columns unitsourceid, alpha
Query: find the solution for event with id 110 that has the set of solution_sources that match the set of (unitsourceid, alpha) in ss_tmp. (This can also be done without the tmp table, I believe.)
Solution:
with solutionids as (
select y.solutionid from (
select ss.solutionid, count(ss.solutionid) x
from solutions s, solution_sources ss
where s.event_id = 110 and ss.solutionid = s.id
group by ss.solutionid
) y where y.x = ( select count(*) from ss_tmp )
)
select solutionids.solutionid from solutionids where
(
select case
when count(*) = ( select count(*) from ss_tmp ) then true
else false
end
from
( SELECT unitsourceid, alpha FROM solution_sources
where solutionid = solutionids.solutionid
INTERSECT
SELECT unitsourceid, alpha FROM ss_tmp ) x
)
Tested against a test query of 4 items and a test db that had a matching solution (same number of child elements, each that matched), several completely non-matching solutions, and 1 solution that had 3 matching child elements, 1 solution that had all 4 matching child elements, plus an additional child, and 1 solution that had 4 child elements of which 3 of the 4 matched the query. Only the id of the true match was returned.
thanks a lot
-Linus
Use EXCEPT statement
When using the EXCEPT statement to test if two sets contain the same rows, you will need to do the EXCEPT in both directions (A EXCEPT B and B EXCEPT A). If either comparison returns any records, then the sets are different. If no records are returned by either, they are the same.
The nice thing about this is that you can do this comparison with any number of specific columns and NULL values are handled implicitly without having to jump through hoops to compare them.
A good use case for this is verifying that saving a set of records happened correctly, especially when affecting an existing set.
SELECT IsMatching = (1 ^ convert(bit, count(*)))
FROM (
SELECT Mismatched = 1 -- Can be any column name
FROM (
SELECT Item -- Can have additional columns
FROM TableA
EXCEPT
SELECT Item -- Can have additional columns
FROM TableB
) as A
UNION
SELECT Mismatched = 1 -- Can be any column name
FROM (
SELECT Item -- Can have additional columns
FROM TableB
EXCEPT
SELECT Item -- Can have additional columns
FROM TableA
) as A
) as A
We have a table which is of the form:
ID,Value1,Value2,Value3
1,2,3,4
We need to transform this into.
ID,Name,Value
1,'Value1',2
1,'Value2',3
1,'Value3',4
Is there a clever way of doing this in one SELECT statement (i.e without UNIONs)? The column names Value1,Value2 and Value3 are fixed and constant.
The database is oracle 9i.
Give a union a shot.
select ID, 'Value1' as Name, Value1 as Value from table_name union all
select ID, 'Value2', Value2 as Value from table_name union all
select ID, 'Value3', Value3 as Value from table_name
order by ID, Name
using union all means that the server won't perform a distinct (which is implicit in union operations). It shouldn't make any difference with the data (since your ID's should HOPEFULLY be different), but it might speed it up a bit.
This works on Oracle 10g:
select id, 'Value' || n as name,
case n when 1 then value1 when 2 then value2 when 3 then value3 end as value
from (select rownum n
from (select 1 from dual connect by level <= 3)) ofs, t
I think Oracle 9i had recursive queries? Anyway, I'm pretty sure it has CASE support, so even if it doesn't have recursive queries, you can just do "(select 1 from dual union all select 2 from dual union all select 3 from dual) ofs" instead. Abusing recursive queries is a bit more general- for Oracle. (Using unions to generate rows is portable to other DBs, though)
You can do it like this, but it's not pretty:
SELECT id,'Value 1' AS name,value1 AS value FROM mytable
UNION
SELECT id,'Value 2' AS name,value2 AS value FROM mytable
UNION
SELECT id,'Value 3' AS name,value3 AS value FROM mytable
Unioning three select statements should do the trick:
SELECT ID, 'Value1', Value1 AS Value
FROM TABLE
UNION
SELECT ID, 'Value2', Value2 AS Value
FROM TABLE
UNION
SELECT ID, 'Value3', Value3 AS Value
FROM TABLE
If you're using SQL Server 2005+ then you can use UNPIVOT
CREATE TABLE #tmp ( ID int, Value1 int, Value2 int, Value3 int)
INSERT INTO #tmp (ID, Value1, Value2, Value3) VALUES (1, 2, 3, 4)
SELECT
*
FROM
#tmp
SELECT
*
FROM
#tmp
UNPIVOT
(
[Value] FOR [Name] IN (Value1, Value2, Value3)
) uPIVOT
DROP TABLE #tmp
A UNION ALL, as others have suggested, is probably your best bet in SQL. You might also want to consider handling this in the front end depending on what your specific requirements are.
CTE syntax may be different for Oracle (I ran it in Teradata), but I only used CTE to provide test data, those 1 2 3 and 4. You can use temp table instead. The actual select statement is plain vanilla SQL and it will on any relational database.
For Sql Server, consider UNPIVOT as an alternative to UNION:
SELECT id, value, colname
FROM #temp t
UNPIVOT (Value FOR ColName IN (value1,value2,value3)) as X
This will return the column name as well. I'm unsure what the X is used for, but you can't leave it out.
Try this:
CTE creates a temp table with 4 values. You can run this as is in any database.
with TEST_CTE (ID) as
(select * from (select '1' as a) as aa union all
select * from (select '2' as b) as bb union all
select * from (select '3' as c) as cc union all
select * from (select '4' as d) as dd )
select a.ID, 'Value'|| a.ID, b.ID
from TEST_CTE a, TEST_CTE b
where b.ID = (select min(c.ID) from TEST_CTE c where c.ID > a.ID)
Here is the result set:
1 Value1 2
2 Value2 3
3 Value3 4
Enjoy!
Some afterthoughts.
^^^ CTE syntax may be different in Oracle. I could only run it in Teradata. You can substitute it with temp table or fix the syntax to make it Oracle compatible. The select statement is plain vanilla SQL that will work on any database.
^^^ Another thing to note. If ID field is numeric, you might need to cast it into CHAR in order to concatenate it with "Value".