Let's say I have the following as a starting point:
select * from (values (1,'a'),(2,'b'))
Is it possible to provide column names to the value columns up-stream, for example something like:
select
col1 AS id,
col2 AS letter
from (
<anonymous values>
)
Or is it basically once you have an anonymous values clause you cannot name it.
You can use a table alias that also specifies column names:
select *
from (
values (1,'a'),(2,'b')
) as v(id, letter);
use an alias:
select * from (values (1,'a'),(2,'b')) as foo(id,txt);
id | txt
----+-----
1 | a
2 | b
(2 rows)
Absolutely
Just add the column names to the query alias
select q.id, q.col
from (values
(1,'a'),
(2,'b')
) q(id, col)
Related
I have the following table tbl:
column1 | column2 | column 3
-----------------------------------
1 | 'value1' | 3
2 | 'value2' | 4
How to do "pivot" with column names to produce output like:
column1 | 1 | 2
column2 | 'value1' |'value2'
column3 | 3 | 4
As has been commented, the issue of data types is undefined in the question.
If you are OK with all result columns being type text (every data type can be converted to text), you can use one of these:
Plain SQL
WITH cte AS (
SELECT nu.*
FROM tbl t
, LATERAL (
VALUES
(1, t.column1::text)
, (2, t.column2)
, (3, t.column3::text)
) nu(rn, c)
)
SELECT *
FROM (TABLE cte OFFSET 0 LIMIT 3) c1
JOIN (TABLE cte OFFSET 3 LIMIT 3) c2 USING (rn);
The same with useful column names:
WITH cte AS (
SELECT nu.*
FROM tbl t
, LATERAL (
VALUES
('column1', t.column1::text)
, ('column2', t.column2)
, ('column3', t.column3::text)
) nu(rn, c)
)
SELECT * FROM (
SELECT *
FROM (TABLE cte OFFSET 0 LIMIT 3) c1
JOIN (TABLE cte OFFSET 3 LIMIT 3) c2 USING (rn)
) t (key, row1, row2);
Works in any modern version of Postgres.
The SQL string has to be adapted to the number of rows and columns. See fiddles below!
Using a document type as stepping stone
Makes for shorter code.
With many rows and many columns, performance of the SQL solution may scale better because the intermediate derived table is smaller.
(The thread is limited as you can't have more than ~ 1600 table columns in Postgres.)
Since everything is converted to text anyway, hstore seems most efficient. See:
Key value pair in PostgreSQL
SELECT key
, arr[1] AS row1
, arr[2] AS row2
FROM (
SELECT x.key, array_agg(x.value) AS arr
FROM tbl t, each(hstore(t)) x
GROUP BY 1
) sub
ORDER BY 1;
Technically speaking we would have to enforce the right sort order when in array_agg(), but that should work without explicit ORDER BY. To be absolutely sure you can add one: array_agg(x.value ORDER BY t.ctid) Using ctid for lack of information.
You can do the same with JSON functions in (Postgres 9.3+). Just replace each(hstore(t) with json_each_text(row_to_json(t). The rest is identical.
These fiddles demonstrate how to scale each query:
Original example with 2 rows of 3 columns:
db<>fiddle here
Scaled up to 3 rows of 4 columns:
db<>fiddle here
I have this (3 int columns in one table)
Int1 Int2 Int3
---------------
1 2 3
I would like to run such query with another someTable:
SELECT * FROM someTable WHERE someInt NOT IN (1,2,3)
where 1,2,3 are list of INTs converted to a list that I can use with SELECT * NOT IN statement
Any suggestions how to achieve this without stored procedures in Micorosft SQL Server 2019 ?
If you want rows in some table that are not in one of three columns of another table, then use not exists:
select t.*
from sometable t
where not exists (select 1
from t t2
where t.someint in (t2.int1, t2.int2, t2.int3)
);
The subquery returns a row where there is a match. The outer query then rejects any rows with a match.
Seems like you actually want a NOT EXISTS?
SELECT {Your Columns}
FROM dbo.someTable sT
WHERE NOT EXISTS (SELECT 1
FROM dbo.oneTable oT
WHERE sT.someInt NOT IN (oT.int1,oT.int2,oT.int3));
An alternative method would be to unpivot the data, and then use an equality operator:
SELECT {Your Columns}
FROM dbo.someTable sT
WHERE NOT EXISTS (SELECT 1
FROM dbo.oneTable oT
CROSS APPLY (VALUES(oT.int1),(oT.int2),(oT.int3))V(I)
WHERE V.I = sT.someInt);
I want to use the like clause to search all columns in a row.
something like
SELECT * FROM test WHERE '%something%' IN *
also, I don't know the exact columns that I have, this is why i need a wildcard (*)
there is a way to do that with snowflake / SQL?
You may consider using array_construct and array_contains:
CREATE or REPLACE TABLE test ( id number, v varchar, z varchar )
as SELECT * FROM VALUES
(1, 'Gokhan', 'Aylin'),
(2, 'Joe', 'Black');
SELECT *, ARRAY_CONSTRUCT( * ) combined
FROM test where ARRAY_CONTAINS( 'Gokhan'::variant, combined );
You can also convert this array to varchar to search partly matching strings:
SELECT *, ARRAY_CONSTRUCT( * ) combined
FROM test
WHERE combined::VARCHAR LIKE '%Go%';
+----+--------+-------+------------------------+
| ID | V | Z | COMBINED |
+----+--------+-------+------------------------+
| 1 | Gokhan | Aylin | [ 1, "Gokhan", "Aylin" |
+----+--------+-------+------------------------+
If you want to search for 'something' in all columns you can try to concatenate all columns in the where clause:
SELECT * from TABLE where CONCAT(colum1,column2,column3) LIKE '%something%'
Remember to cast to string type any non string type column.
You have to little tweak the SQL, concat takes all data types
select a.* from (
select *, concat(*) as all_col_data from snowflake.schema.table_name
) as a
where a.all_col_data like '%something%'
Is there a built in function for comma separated column values in DB2 SQL?
Example: If there are columns with an ID and it has 3 rows with the same ID but have three different roles, the data should be concatenated with a comma.
ID | Role
------------
4555 | 2
4555 | 3
4555 | 4
The output should look like the following, per row:
4555 2,3,4
LISTAGG function is new function in DB2 LUW 9.7
see example:
create table myTable (id int, category int);
insert into myTable values (1, 1);
insert into myTable values (2, 2);
insert into myTable values (5, 1);
insert into myTable values (3, 1);
insert into myTable values (4, 2);
example: select without any order in grouped column
select category, LISTAGG(id, ', ') as ids from myTable group by category;
result:
CATEGORY IDS
--------- -----
1 1, 5, 3
2 2, 4
example: select with order by clause in grouped column
select
category,
LISTAGG(id, ', ') WITHIN GROUP(ORDER BY id ASC) as ids
from myTable
group by category;
result:
CATEGORY IDS
--------- -----
1 1, 3, 5
2 2, 4
I think with this smaller query, you can do what you want.
This is equivalent of MySQL's GROUP_CONCAT in DB2.
SELECT
NUM,
SUBSTR(xmlserialize(xmlagg(xmltext(CONCAT( ', ',ROLES))) as VARCHAR(1024)), 3) as ROLES
FROM mytable
GROUP BY NUM;
This will output something like:
NUM ROLES
---- -------------
1 111, 333, 555
2 222, 444
assumming your original result was something like that:
NUM ROLES
---- ---------
1 111
2 222
1 333
2 444
1 555
Depending of the DB2 version you have, you can use XML functions to achieve this.
Example table with some data
create table myTable (id int, category int);
insert into myTable values (1, 1);
insert into myTable values (2, 2);
insert into myTable values (3, 1);
insert into myTable values (4, 2);
insert into myTable values (5, 1);
Aggregate results using xml functions
select category,
xmlserialize(XMLAGG(XMLELEMENT(NAME "x", id) ) as varchar(1000)) as ids
from myTable
group by category;
results:
CATEGORY IDS
-------- ------------------------
1 <x>1</x><x>3</x><x>5</x>
2 <x>2</x><x>4</x>
Use replace to make the result look better
select category,
replace(
replace(
replace(
xmlserialize(XMLAGG(XMLELEMENT(NAME "x", id) ) as varchar(1000))
, '</x><x>', ',')
, '<x>', '')
, '</x>', '') as ids
from myTable
group by category;
Cleaned result
CATEGORY IDS
-------- -----
1 1,3,5
2 2,4
Just saw a better solution using XMLTEXT instead of XMLELEMENT here.
Since DB2 9.7.5 there is a function for that:
LISTAGG(colname, separator)
check this for more information: Using LISTAGG to Turn Rows of Data into a Comma Separated List
My problem was to transpose row fields(CLOB) to column(VARCHAR) with a CSV and use the transposed table for reporting. Because transposing on report layer slows down the report.
One way to go is to use recursive SQL. You can find many articles about that but its difficult and resource consuming if you want to join all your recursive transposed columns.
I created multiple global temp tables where I stored single transposed columns with one key identifier. Eventually, I had 6 temp tables for joining 6 columns but due to limited resource allocation I wasnt able to bring all columns together. I opted to below 3 formulas and then I just had to run 1 query which gave me output in 10 seconds.
I found various articles on using XML2CLOB functions and have found 3 different ways.
REPLACE(VARCHAR(XML2CLOB(XMLAGG(XMLELEMENT(NAME "A",ALIASNAME.ATTRIBUTENAME)))),'', ',') AS TRANSPOSED_OUTPUT
NVL(TRIM(',' FROM REPLACE(REPLACE(REPLACE(CAST(XML2CLOB(XMLAGG(XMLELEMENT(NAME "E", ALIASNAME.ATTRIBUTENAME))) AS VARCHAR(100)),'',' '),'',','), '', 'Nothing')), 'Nothing') as TRANSPOSED_OUTPUT
RTRIM(REPLACE(REPLACE(REPLACE(VARCHAR(XMLSERIALIZE(XMLAGG(XMLELEMENT(NAME "A",ALIASNAME.ATTRIBUTENAME) ORDER BY ALIASNAME.ATTRIBUTENAME) AS CLOB)), '',','),'',''),'','')) AS TRANSPOSED_OUTPUT
Make sure you are casting your "ATTRIBUTENAME" to varchar in a subquery and then calling it here.
other possibility, with recursive cte
with tablewithrank as (
select id, category, rownumber() over(partition by category order by id) as rangid , (select count(*) from myTable f2 where f1.category=f2.category) nbidbycategory
from myTable f1
),
cte (id, category, rangid, nbidbycategory, rangconcat) as (
select id, category, rangid, nbidbycategory, cast(id as varchar(500)) from tablewithrank where rangid=1
union all
select f2.id, f2.category, f2.rangid, f2.nbidbycategory, cast(f1.rangconcat as varchar(500)) || ',' || cast(f2.id as varchar(500)) from cte f1 inner join tablewithrank f2 on f1.rangid=f2.rangid -1 and f1.category=f2.category
)
select category, rangconcat as IDS from cte
where rangid=nbidbycategory
Try this:
SELECT GROUP_CONCAT( field1, field2, field3 ,field4 SEPARATOR ', ')
Is there a built in function for comma separated column values in DB2 SQL?
Example: If there are columns with an ID and it has 3 rows with the same ID but have three different roles, the data should be concatenated with a comma.
ID | Role
------------
4555 | 2
4555 | 3
4555 | 4
The output should look like the following, per row:
4555 2,3,4
LISTAGG function is new function in DB2 LUW 9.7
see example:
create table myTable (id int, category int);
insert into myTable values (1, 1);
insert into myTable values (2, 2);
insert into myTable values (5, 1);
insert into myTable values (3, 1);
insert into myTable values (4, 2);
example: select without any order in grouped column
select category, LISTAGG(id, ', ') as ids from myTable group by category;
result:
CATEGORY IDS
--------- -----
1 1, 5, 3
2 2, 4
example: select with order by clause in grouped column
select
category,
LISTAGG(id, ', ') WITHIN GROUP(ORDER BY id ASC) as ids
from myTable
group by category;
result:
CATEGORY IDS
--------- -----
1 1, 3, 5
2 2, 4
I think with this smaller query, you can do what you want.
This is equivalent of MySQL's GROUP_CONCAT in DB2.
SELECT
NUM,
SUBSTR(xmlserialize(xmlagg(xmltext(CONCAT( ', ',ROLES))) as VARCHAR(1024)), 3) as ROLES
FROM mytable
GROUP BY NUM;
This will output something like:
NUM ROLES
---- -------------
1 111, 333, 555
2 222, 444
assumming your original result was something like that:
NUM ROLES
---- ---------
1 111
2 222
1 333
2 444
1 555
Depending of the DB2 version you have, you can use XML functions to achieve this.
Example table with some data
create table myTable (id int, category int);
insert into myTable values (1, 1);
insert into myTable values (2, 2);
insert into myTable values (3, 1);
insert into myTable values (4, 2);
insert into myTable values (5, 1);
Aggregate results using xml functions
select category,
xmlserialize(XMLAGG(XMLELEMENT(NAME "x", id) ) as varchar(1000)) as ids
from myTable
group by category;
results:
CATEGORY IDS
-------- ------------------------
1 <x>1</x><x>3</x><x>5</x>
2 <x>2</x><x>4</x>
Use replace to make the result look better
select category,
replace(
replace(
replace(
xmlserialize(XMLAGG(XMLELEMENT(NAME "x", id) ) as varchar(1000))
, '</x><x>', ',')
, '<x>', '')
, '</x>', '') as ids
from myTable
group by category;
Cleaned result
CATEGORY IDS
-------- -----
1 1,3,5
2 2,4
Just saw a better solution using XMLTEXT instead of XMLELEMENT here.
Since DB2 9.7.5 there is a function for that:
LISTAGG(colname, separator)
check this for more information: Using LISTAGG to Turn Rows of Data into a Comma Separated List
My problem was to transpose row fields(CLOB) to column(VARCHAR) with a CSV and use the transposed table for reporting. Because transposing on report layer slows down the report.
One way to go is to use recursive SQL. You can find many articles about that but its difficult and resource consuming if you want to join all your recursive transposed columns.
I created multiple global temp tables where I stored single transposed columns with one key identifier. Eventually, I had 6 temp tables for joining 6 columns but due to limited resource allocation I wasnt able to bring all columns together. I opted to below 3 formulas and then I just had to run 1 query which gave me output in 10 seconds.
I found various articles on using XML2CLOB functions and have found 3 different ways.
REPLACE(VARCHAR(XML2CLOB(XMLAGG(XMLELEMENT(NAME "A",ALIASNAME.ATTRIBUTENAME)))),'', ',') AS TRANSPOSED_OUTPUT
NVL(TRIM(',' FROM REPLACE(REPLACE(REPLACE(CAST(XML2CLOB(XMLAGG(XMLELEMENT(NAME "E", ALIASNAME.ATTRIBUTENAME))) AS VARCHAR(100)),'',' '),'',','), '', 'Nothing')), 'Nothing') as TRANSPOSED_OUTPUT
RTRIM(REPLACE(REPLACE(REPLACE(VARCHAR(XMLSERIALIZE(XMLAGG(XMLELEMENT(NAME "A",ALIASNAME.ATTRIBUTENAME) ORDER BY ALIASNAME.ATTRIBUTENAME) AS CLOB)), '',','),'',''),'','')) AS TRANSPOSED_OUTPUT
Make sure you are casting your "ATTRIBUTENAME" to varchar in a subquery and then calling it here.
other possibility, with recursive cte
with tablewithrank as (
select id, category, rownumber() over(partition by category order by id) as rangid , (select count(*) from myTable f2 where f1.category=f2.category) nbidbycategory
from myTable f1
),
cte (id, category, rangid, nbidbycategory, rangconcat) as (
select id, category, rangid, nbidbycategory, cast(id as varchar(500)) from tablewithrank where rangid=1
union all
select f2.id, f2.category, f2.rangid, f2.nbidbycategory, cast(f1.rangconcat as varchar(500)) || ',' || cast(f2.id as varchar(500)) from cte f1 inner join tablewithrank f2 on f1.rangid=f2.rangid -1 and f1.category=f2.category
)
select category, rangconcat as IDS from cte
where rangid=nbidbycategory
Try this:
SELECT GROUP_CONCAT( field1, field2, field3 ,field4 SEPARATOR ', ')