I'm having trouble return the correct information with my select statement
table:
prefix | suffix | alternate
------ | ------ | --------
A | 12345 | 0
B | 67890 | 0
C | 0 | 555555
Here is my query
SELECT
CASE WHEN prefix = 'C' THEN alternate
ELSE CONCAT(prefix, suffix) END as Result
FROM table
What I would like to see as a result:
Result
------
A12345
B67890
555555
What I actually see:
555555
if I take out the CONCAT using this select
SELECT
CASE WHEN prefix = 'C' THEN alternate
ELSE suffix END as Result
FROM table
I get the number of rows I want but not the correct column values. I'm missing the prefix in the first two rows.
Result
12345
67890
555555
Thoughts on how I can do this without duplicating code with union?
Select concat(prefix,suffix) as result from table
union
select alternate as result from table
You can do something like this
SELECT
CASE WHEN prefix <> 'C'
THEN prefix||suffix
ELSE cast (alternate as char(20))
END as Result
FROM table
Related
I am trying the following with Db2:
Problem
So I've got a table with 80+ columns and two rows.
I need to accomplish is checking what columns have changed value between the two rows, and return a table of the column names that have changed, their initial value from row1, and their new value from row2.
Approach so far
My initial idea was to perform a pivot of the two rows into two columns, row 1 as column 1, row 2 as column 2, then join a column of column names (likely taken from syscat.columns) to the table as column 3, at which point I can then do a select where column1 != column2, hence returning the rows with all the data needed. But alas, it was not long after coming up with this that I discover DB2 doesn't support pivot / unpivot...
Question
So is there any idea for how to accomplish this in DB2, taking a table with 80+ columns and two rows like so:
| Col A | Col B | Col C | ... | Col Z|
| ----- | ----- | ----- | --- | ---- |
| Val A | Val B | 123 | ... | 01/01/2021 |
| Val C | Val B | 124 | ... | 02/01/2021 |
And returning a table with the columns changed, their initial value, and their new value:
| Initial | New | ColName|
| ----- | ----- | ----- |
| Val A | Val C | Col A |
| 123 | 124 | Col C |
| 01/01/2021 | 02/01/2021 | Col Z |
Also note the column data types also vary, so will need to be converted to varchar
DB2 version is 11.1
EDIT: Also for reference as per comment request, this is code I attempted to use to achieve this goal:
WITH
INIT AS (SELECT * FROM TABLE WHERE SOMEDATE=(SELECT MIN(SOMEDATE) FROM TABLE),
LATE AS (SELECT * FROM TABLE WHERE SOMEDATE=(SELECT MAX(SOMEDATE) FROM TABLE),
COLS AS (SELECT COLNAME FROM SYSCAT.COLUMNS WHERE TABNAME='TABLE' ORDER BY COLNO)
SELECT * FROM (
SELECT
COLNAME AS ATTRIBUTE,
(SELECT COLNAME AS INITIAL FROM INIT),
(SELECT COLNAME AS NEW FROM LATE)
FROM
COLS
WHERE
(INITIAL != NEW) OR (INITIAL IS NULL AND NEW IS NOT NULL) OR (INITIAL IS NOT NULL AND NEW IS NULL));
Only issue with this one is that I couldn't figure how to use the values from the COLS table as the columns to be selected
You may easily generate text of the expressions needed, if you don't want to type them manually.
Consider the following example, if you want to print different column values only in 2 rows of the same quite a wide table SYSCAT.TABLES. We use the following query for such an expression generation.
SELECT
'DECODE(I.I, '
|| LISTAGG(COLNO || ', A.' || COLNAME || CASE WHEN TYPENAME NOT LIKE '%CHAR%' AND TYPENAME NOT LIKE '%GRAPHIC' THEN '::VARCHAR(128)' ELSE '' END, ', ')
|| ') AS INITIAL' AS EXPR_INITIAL
, 'DECODE(I.I, '
|| LISTAGG(COLNO || ', B.' || COLNAME || CASE WHEN TYPENAME NOT LIKE '%CHAR%' AND TYPENAME NOT LIKE '%GRAPHIC' THEN '::VARCHAR(128)' ELSE '' END, ', ')
|| ') AS NEW' AS EXPR_NEW
, 'DECODE(I.I, '
|| LISTAGG(COLNO || ', ''' || COLNAME || '''', ', ')
|| ') AS COLNAME' AS EXPR_COLNAME
FROM SYSCAT.COLUMNS C
WHERE TABSCHEMA = 'SYSCAT' AND TABNAME = 'TABLES'
AND TYPENAME NOT LIKE '%LOB';
It doesn't matter how many columns the table contains. We just filter out the columns of *LOB types as an example. If you want them as well, you should change the ::VARCHAR(128) casting to some ::CLOB(XXX).
These 3 generated expressions we put to the corresponding places in the query below:
WITH MYTAB AS
(
-- We enumerate the rows to reference them later
SELECT ROWNUMBER() OVER () RN_, T.*
FROM SYSCAT.TABLES T
WHERE TABSCHEMA = 'SYSCAT'
FETCH FIRST 2 ROWS ONLY
)
SELECT *
FROM
(
SELECT
-- Place here the result got in the EXPR_INITIAL column
-- , Place here the result got in the EXPR_NEW column
-- , Place here the result got in the EXPR_COLNAME column
FROM MYTAB A, MYTAB B
,
(
SELECT COLNO AS I
FROM SYSCAT.COLUMNS
WHERE TABSCHEMA = 'SYSCAT' AND TABNAME = 'TABLES'
AND TYPENAME NOT LIKE '%LOB'
) I
WHERE A.RN_ = 1 AND B.RN_ = 2
)
WHERE INITIAL IS DISTINCT FROM NEW;
The result I got in my database:
|INITIAL |NEW |COLNAME |
|--------------------------|--------------------------|---------------|
|2019-06-04-22.44.14.493001|2019-06-04-22.44.14.502001|ALTER_TIME |
|26 |15 |COLCOUNT |
|2019-06-04-22.44.14.493001|2019-06-04-22.44.14.502001|CREATE_TIME |
|2019-06-04-22.44.14.493001|2019-06-04-22.44.14.502001|INVALIDATE_TIME|
|2019-06-04-22.44.14.493001|2019-06-04-22.44.14.502001|LAST_REGEN_TIME|
|ATTRIBUTES |AUDITPOLICIES |TABNAME |
I have a function test_func() that takes in 1 argument (let's say the argument name is X) and returns a table. Now, I have a list of inputs (from a subquery) that I want to pass into argument X and collect all the results of the calls in a table.
In Python, I would do something like
# create empty list
all_results = []
for argument in (1,2,3):
result = test_func(argument)
# Collect the result
all_results.append(result)
return all_results
How can I do the same thing in postgresql?
Thank you.
For the sake of example, my test_func(X) takes in 1 argument and spits out a table with 3 columns. The values for col1 is X, col2 is X+1 and col3 is X+3. For example:
select * from test_func(1)
gives
|col1|col2|col3|
----------------
| 1 | 2 | 3 |
----------------
My list of arguments would be results of a subquery, for example:
select * from (values (1), (2)) x
I expect something like:
|col1|col2|col3|
----------------
| 1 | 2 | 3 |
----------------
| 2 | 3 | 4 |
----------------
demo:db<>fiddle
This gives you a result list of all results:
SELECT
mt.my_data as input,
tf.*
FROM
(SELECT * FROM my_table) mt, -- input data from a subquery
test_func(my_data) tf -- calling every data set as argument
In the fiddle the test_func() gets an integer and generates rows (input argument = generated row count). Furthermore, it adds a text column. For all inputs all generated records are unioned into one result set.
You can join your function to the input values:
select f.*
from (
values (1), (2)
) as x(id)
cross join lateral test_func(x.id) as f;
I have one array with column values as
{james=UC/james,adam=C/james,chris=UC/james,john=U/james}
The above column values are not json. They are in string in the following form:
{ username=privilegestring/grantor }
How to convert above column into multiple rows
Edit #3:
Updated the query to specifically target pg_catalog.pg_namespace for acl permissions grants, via CTE pg_catalog. Currently this CTE is filtered in the where clause to select a single namespace name ('avengers'); if you want to select from multiple namespace names, you should be able to add them into the WHERE clause of this CTE directly, or in the case of wanting all namespace names, remove the clause altogether.
It's worth noting as well, that you will need to expand the case statements in access_privilege_types to handle all permissions cases: 'r', 'w', 'a', 'd', and 'x', for the operations: SELECT, UPDATE, INSERT, DELETE, REFERENCE, respectively.
Edit #2:
The final posted version of the query below should get you the data you want in the format that you want it in. I don't know how many possible values there are for the permissions types; if you have more than the two specified currently, you will need to expand the case statements in the CTE* access_privilege_types*. Obviously you'll also need to replace your table name within the query, etc.. Let me know if you run into any trouble and I'll help as necessary.
Edit #1:
Was able to validate that this query works in Redshift. Updated the query to break out separate rows by grantee and owner. The current version doesn't break out individual permissions by row yet -- Will take a look later tonight to see if I can get that working as well.
Original:
I don't have access to my Redshift cluster to test this at the moment, but I will when I get home. The general idea behind the following method, is to create a numbered index table to cross join against that will expand the data in the permissions field into a row-based representation.
I had inquired about the size limit, because this will currently only handle 10,000 possible delimited values, however you can adjust the CTEs to scale up to larger amounts if needed for your specific application:
Revision 3 Query:
WITH
pg_namespace AS (
SELECT
nspname
, nspowner
, rtrim(ltrim(array_to_string(nspacl, ','), '{'), '}') as nspacl
FROM pg_catalog.pg_namespace
WHERE nspname = 'public'
),
-- Generating a table with the numbers 1 - 10 in a single column.
ten_numbers AS (
SELECT
1 AS num
UNION SELECT 2
UNION SELECT 3
UNION SELECT 4
UNION SELECT 5
UNION SELECT 6
UNION SELECT 7
UNION SELECT 8
UNION SELECT 9
UNION SELECT 0
),
-- Expands the values in ten_numbers to create a single column with the values 1 - 10,000.
depivot_index AS (
SELECT
(1000 * t1.num) + (100 * t2.num) + (10 * t3.num) + t4.num AS gen_num
FROM ten_numbers AS t1
JOIN ten_numbers AS t2 ON 1 = 1
JOIN ten_numbers AS t3 ON 1 = 1
JOIN ten_numbers AS t4 ON 1 = 1
),
-- Filters down generated_numbers to house only the numbers up to the maximum times that the delimiter appears.
splitter AS (
SELECT
*
FROM depivot_index
WHERE gen_num BETWEEN 1 AND (
SELECT max(REGEXP_COUNT(nspacl, '\\,') + 1)
FROM pg_namespace
)
),
-- Cross joins permissions_groups and splitter to populate all requests, delimited on ','.
expanded_input AS (
SELECT
pg.nspname
, pg.nspacl
, trim(split_part(pg.nspacl, ',', s.gen_num)) AS raw_permissions_string
FROM pg_namespace AS pg
JOIN splitter AS s ON 1 = 1
WHERE split_part(nspacl, ',', s.gen_num) <> ''
),
-- Breaks out the owner and grantee fields into their own columns respectively.
users_with_raw_permissions_data AS (
SELECT
e.raw_permissions_string
, e.nspname
, trim(split_part(e.raw_permissions_string, '=', 1)) AS grantee
, trim(split_part(trim(split_part(e.raw_permissions_string, '=', 2)), '/', 2)) AS owner
, trim(split_part(trim(split_part(e.raw_permissions_string, '=', 2)), '/', 1)) AS raw_permissions_data
FROM
expanded_input e
),
-- Mines privilege types from raw string data.
access_privilege_types AS (
SELECT
u.nspname
, u.owner
, u.grantee
,CASE
WHEN position('C*' IN u.raw_permissions_data) > 0 THEN 'C*'
WHEN position('U*' IN u.raw_permissions_data) > 0 THEN 'U*'
WHEN position('C' IN u.raw_permissions_data) > 0 THEN 'C'
WHEN position('U' IN u.raw_permissions_data) > 0 THEN 'U'
ELSE u.raw_permissions_data
END AS first_access_privilege
, CASE
WHEN position('U*' IN u.raw_permissions_data) > 0 THEN 'U*'
WHEN position('C*' IN u.raw_permissions_data) > 0 THEN 'C*'
WHEN position('U' IN u.raw_permissions_data) > 0 THEN 'U'
WHEN position('C' IN u.raw_permissions_data) > 0 THEN 'C'
ELSE u.raw_permissions_data
END AS second_access_privilege
, first_access_privilege || ',' || second_access_privilege AS merged_access_privileges
FROM users_with_raw_permissions_data u
),
-- Cross joins access_privilge_types and splitter to populate all privilege_types, delimited on ','.
expanded_access_privilege_types AS (
SELECT
a.nspname
, a.owner
, a.grantee
, trim(split_part(a.merged_access_privileges, ',', s.gen_num)) AS access_privileges
FROM access_privilege_types AS a
JOIN splitter AS s ON 1 = 1
WHERE split_part(a.merged_access_privileges, ',', s.gen_num) <> ''
GROUP BY 1, 2, 3, 4
)
SELECT
ea.nspname
, ea.owner
, ea.grantee
, LEFT(ea.access_privileges, 1) AS access_privilege
, CASE
WHEN POSITION('*' IN ea.access_privileges) > 0 THEN 'YES'
ELSE 'NO'
END AS is_grantable
FROM expanded_access_privilege_types ea
ORDER BY 1, 2, 3, 4, 5
Edit #4:
Adding some clarification on how the ten_numbers, depivot_index, and splitter tables work to break apart the pg_catalog.pg_namespace.nspacl field. The general overview, is that ten_numbers and depivot_index are created purely to return tables with numbered rows to use as an index when joining in thesplit_partvalues ofnspacl`.
ten_numbers generates a table with a single column, containing the numbers 0-9:
-------
| num |
-------
| 0 |
-------
| 1 |
-------
| etc |
-------
| 9 |
-------
This table is then expanded to house the range 0-9999 during the CTE depivot_index:
-----------
| gen_num |
-----------
| 0 |
-----------
| 1 |
-----------
| 2 |
-----------
| etc |
-----------
| 9998 |
-----------
| 9999 |
-----------
splitter then narrows down the table to house only the numbers up to the maximum count of the specified delimiter within the nspacl field:
-------
| num |
-------
| 0 |
-------
| 1 |
-------
| etc |
-------
| 6 |
-------
The table returned by splitter is then used as the target of a CROSS JOIN via the join on 1 = 1 in CTE expanded_input. This ensures that each member returned by split_part will have its own row:
---------------------------------------------------------------------------
| nspname | nspacl | raw_permissions_string |
---------------------------------------------------------------------------
| avengers | "{james=UC/james,adam=C/james}" | "james=UC/james" |
---------------------------------------------------------------------------
| avengers | "{james=UC/james,adam=C/james}" | "adam=C/james" |
---------------------------------------------------------------------------
| avengers | etc. | etc. |
---------------------------------------------------------------------------
I have:
user_id|user_name|user_action
-----------------------------
1 | Shone | start,stop,cancell
I would like to see:
user_id|user_name|parsed_action
-------------------------------
1 | Shone | start
1 | Shone | start,stop
1 | Shone | start,cancell
1 | Shone | start,stop,cancell
1 | Shone | stop
1 | Shone | stop,cancell
1 | Shone | cancell
....
You can create the following Python UDF:
create or replace function get_unique_combinations(list varchar(max))
returns varchar(max)
stable as $$
from itertools import combinations
arr = list.split(',')
response = []
for L in range(1, len(arr)+1):
for subset in combinations(arr, L):
response.append(','.join(subset))
return ';'.join(response)
$$ language plpythonu;
that will take your list of actions and return unique combinations separated by semicolon (elements in combinations themselves will be separated by commas). Then you use a UNION hack to split values into separate rows like this:
WITH unique_combinations as (
SELECT
user_id
,user_name
,get_unique_combinations(user_actions) as action_combinations
FROM your_table
)
,unwrap_lists as (
SELECT
user_id
,user_name
,split_part(action_combinations,';',1) as parsed_action
FROM unique_combinations
UNION ALL
SELECT
user_id
,user_name
,split_part(action_combinations,';',2) as parsed_action
FROM unique_combinations
-- as much UNIONS as possible combinations you have for a single element, with the 3rd parameter (1-based array index) increasing by 1
)
SELECT *
FROM unwrap_lists
WHERE parsed_action is not null
Im sorting the values. Postgres is ignoring "-". Here's my query:
select 0 as key,
'------ select ------' as value
union
SELECT contact_replica_child.contact_id as key,
contact_replica_child.last_name||', '||contact_replica_child.first_name as value
FROM contact_replica_child
join listing_replica_child on contact_replica_child.administrative_agency_id = listing_replica_child.agency_id
where listing_replica_child.session_id = '3edfa73687a53604a50708d3d5d90221'
order by value ;
Im getting this:
key | value
--------+-------------------------
581489 | Contact, Administrative
581490 | Green, Kelley
0 | ------ select ------
Im expecting this:
key | value
--------+-------------------------
0 | ------ select ------
581489 | Contact, Administrative
581490 | Green, Kelley
Any solution?
Although I must admit I don't understand why Postgres is acting this way, you can easily work around it by limiting the order by clause to the second query only, using parentheses:
SELECT 0 AS key, '------ select ------' AS value
UNION ALL
(SELECT contact_replica_child.contact_id AS key,
contact_replica_child.last_name || ',' || contact_replica_child.first_name AS value
FROM contact_replica_child
JOIN listing_replica_child ON
contact_replica_child.administrative_agency_id =
listing_replica_child.agency_id
WHERE listing_replica_child.session_id = '3edfa73687a53604a50708d3d5d90221'
ORDER BY value
);