How can I CASE WHEN table name in a Hive SELECT query?
I want to do something to the effect of -
SELECT col1, col2
FROM
CASE ${PARAM}
WHEN 'val1' THEN table1
WHEN 'val2' THEN table2
This is possible. Rewrite your query like this:
SELECT col1, col2 FROM table1 WHERE '${PARAM}' = 'val1' --only one subquery will be executed
union all
SELECT col1, col2 FROM table2 WHERE '${PARAM}' = 'val2'
Related
How to find difference of two tables based on different group: I have a below scenario:
(TABLE1
COL1=1,2,3,4,5
Table2
COL1=1,2,3,4,5
COL2=A,B,C.....
COL3=XXX OR BLANK
output
1A,1B,1C,2A,2B
)
I got the below sql but my column2 has 40 different value and it will be a big union all statement. Also the comparison needs to be done with all entries of table 1 needs to compare with table2 as A has (1,2,3 in table1 ) B has (2,3 in table2) any way to achieve it efficiently will be highly appreciated ?
Edit:
Col2 value should not be hardcoded it should be distinct value from Table2, it can be from a-z, so my below union all will have 26 statement having same code just col2 will changeenter image description here
/*SQL that is working result: */
SELECT col1
FROM table1
WHERE col1 NOT IN (
SELECT col1
FROM table2
WHERE col3 = 'xxx'
AND col2 = 'A'
)
UNION ALL
SELECT col1
FROM table1
WHERE col1 NOT IN (
SELECT col1
FROM table2
WHERE col3 = 'xxx'
AND col2 = 'B'
)
UNION ALL
SELECT col1
FROM table1
WHERE col1 NOT IN (
SELECT col1
FROM table2
WHERE col3 = 'xxx'
AND col2 = 'C'
)
Are you looking for logic like this? For your example all the col3s are the same, so:
SELECT t1.col1
FROM table1 t1
WHERE NOT EXISTS (SELECT 1
FROM table2 t2
WHERE t2.col1 = t1.col1 AND
t2.col3 = 'xxx' AND
t2.col1 IN ('A', 'B', 'C')
);
This assumes that the comparison on col3 is always 'xxx' as in your example. The logic can easily be tweaked if that is not the case.
I am currently using UNION on two queries (see psuedo-code below):
query1
UNION
query2
I want to add an additional column to my results that says the source of the data. The new column called "Source" would return one of the following: "1", "2", or "both".
Being able to handle "both" is very important because query1 and query2 will have similar results and many overlapping records. If anyone could help point me in the right direction, especially with how to handle the "both" case, that would be greatly appreciated!
Sample:
If query1 has a row "Apple,Yellow,Bob" and query2 has the same row, then the result I'm hoping for is:
"Apple,Yellow,Bob,Both"
The individual queries themselves will not have duplicates, but there may be the same row both in query1 and query2 (as seen above).
you can make use of an additional column col4 like this
select col1,col2,col3,sum(col4)
from(
Select col1, col2, col3, 1 as col4 from table1
UNION
Select col1,col2,col3, 2 as col4 from table4
)
group by col1,col2,col3
The records with col4=1 only exist in table1.
The records with col4=2 only exist in table2.
The records with col4=3 exist in both table1+table
add a Source field to both query 1 and query 2:
select 1 as source, ...
from table1
union
select 2 as source, ...
from table2
Here's one way
WITH T
AS (SELECT '1' AS Source,
Col1,
Col2,
Col3
FROM table1
UNION ALL
SELECT '2' AS Source,
Col1,
Col2,
Col3
FROM table2)
SELECT CASE
WHEN MAX(Source) = MIN(Source) THEN Source
ELSE 'Both'
END AS Source,
Col1,
Col2,
Col3
FROM T
GROUP BY Col1,
Col2,
Col3
One more approach
SELECT col1
,col2
,source = CASE
WHEN count(DISTINCT source) > 1
THEN 'Both'
ELSE max(source)
END
FROM (
SELECT col1 ,col2, source = 'source1'
FROM source1
UNION ALL
SELECT col1, col2, source = 'source2'
FROM source2
) u
GROUP BY col1, col2
You can try this
SELECT
a.col1 , a.col2,
CASE WHEN MAX(a.Source) <> MIN(a.Source)
THEN 'BOTH'
ELSE MAX(a.Source) END
FROM
(
SELECT
col1, col2 ,'Source2' AS Source
FROM Table1
UNION ALL
SELECT
col1, col2 ,'Source1' AS Source
FROM Table2
) a
GROUP BY
a.col1 , a.col2
Link to the Sample
I'm trying to write a query that pulls data from a lot of tables, and has about 20 unions. It's pulling the same information repeatedly, but with more layers each time, to show a sort of tree.
I want to compare the final two columns. I'm using a case to do this, and if I add a case to this query then I get the error "query block has incorrect number of results columns". This seems to be because the final select in the union has an extra column (the compare case).
Is there any way to work around this? I don't want to add the case to each select, as this would add about 15 more columns that I don't want.
Use a sub-query:
SELECT col1,
col2,
CASE
WHEN col1 = 'somevalue'
THEN 'someresult'
ELSE 'otherresult'
END AS col3
FROM (
SELECT col1, col2 FROM table1 UNION ALL
SELECT col1, col2 FROM table2 UNION ALL
SELECT col1, col2 FROM table3
-- ...
);
Or use a sub-query factoring clause:
WITH data ( col1, col2 ) AS (
SELECT col1, col2 FROM table1 UNION ALL
SELECT col1, col2 FROM table2 UNION ALL
SELECT col1, col2 FROM table3
-- ...
)
SELECT col1,
col2,
CASE
WHEN col1 = 'somevalue'
THEN 'someresult'
ELSE 'otherresult'
END AS col3
FROM data;
I have 12 tables in SQL Server with the exact same columns that I would like to combine into one brand new table. I don't want any data/rows deleted.
Thanks
Use union all:
insert into NewTable(col1, col2)
select col1, col2
from(
select col1, col2 from Table1
union all
select col1, col2 from Table2
union all
select col1, col2 from Table3
.....
)t
You can create new table while selecting like:
select col1, col2
into NewTable
from(
select col1, col2 from Table1
union all
select col1, col2 from Table2
union all
select col1, col2 from Table3
.....
)t
lets say I have a table called table1 and it's corresponding columns are col1, col2, col3 and col4 for example.
what will be the equivalent thing of doing:
-- note that the following query will not work
SELECT *
FROM table1
WHERE col1, col2 IN (SELECT col1, col2
FROM table1
WHERE col3 < 4)
Do I have to merge col1 and col2 in my database to make this work? If I merge col1 and col2 into col1_2 then I will be able to make the above query work by writing:
SELECT *
FROM table1
WHERE col1_2 IN (SELECT col1_2
FROM table1
WHERE col3 < 4)
The IN clause works fine when using one column. it will be nice if I could use it with several columns without having to modify the database.
SELECT * from table1 t1, table1 t2
where t1.col1=t2.col1 and t1.COl2=t2.Col2 and t1.col3<4
try this one
Equivalent of what you showed is:
SELECT *
FROM table1 tb1
WHERE EXISTS
(
SELECT *
FROM table1 tb2
WHERE
tb1.col1 = tb2.col1 and
tb1.col2 = tb2.col2 and
tb2.col3 < 4
)
However, this query does not make much sense as it is equivalent of
SELECT *
FROM table1 tb1
WHERE tb2.col3 < 4
I just assume that the example you show is not well thought out.