I am trying to generate a crosstab of data in Report Studio but failed.
The data in the list I have is:
ID, Product, Grade
1, Product1, D
1, Product2, C
1, Product3, D
2, Product1, C
2, Product2, C
2, Product3, A
I want a crosstab of:
ID, Product1, Product2, Product3
1, D,C, D
2, C, C, A
But the crosstab I generate in Cognos gives me either all blank or a count or sum of "Grade".
ID, Product1, Product2, Product3
1,
2,
Any help will be greatly appreciated. Thank you so much in advance.
Best,
Tom
Crosstab works only for numbers.
So measure for crosstab should not be A, B, C.
Use number as a measure (A = 1, B = 2 etc), use MAX or MIN as an aggregate.
Then convert your number to text inside cell. For example, change the Source Type property to Report Expression and write suitable formula. (Or unlock cell and drag Query Calculation inside)
You can't do things like
ID|Product1|Product2|Product3
1 | D,A | C | D
2 | C | C | A
simply.
If I understand you correctly, you'll need to use a case statement for your product grade columns:
ID PRODUCT1
1 case when Product = 'Product1' then grade else null end
You may need to wrap the case statement in a MAX, not sure without trying it.
From what you said you need it looks like a list is the best option.
ID | Case when [Product] = 'Product1' then [grade] end | same for product 2 and 3
Related
Assume a table like this one:
a | b | total
--|---|------
1 | 2 | 3
4 | 7 | 11
…
CREATE TEMPORARY TABLE summedup (
a double precision DEFAULT 0
, b double precision DEFAULT 0
--, total double precision
);
INSERT INTO summedup (a, b) VALUES (1, 2);
INSERT INTO summedup (a, b) VALUES (4, 7);
SELECT a, b, a + b as total FROM summedup;
It's easy to sum up the first two columns on SELECT.
But does Postgres (9.6) also support the ability to define total as the sum of the other two columns? If so:
What is the syntax?
What is this type of operation called (aggregates typically sum up cells over multiple rows, not columns.)
What you are looking for is typically called a "computed column".
Postgres 9.6 does not support that (Postgres 12 - to be released in Q4 2019 - will).
But for such a simple sum, I wouldn't bother storing redundant information.
If you don't want to repeat the expression, create a view.
I think what you want is a View.
CREATE VIEW table_with_sum AS
SELECT id, a, b, a + b as total FROM summedup;
then you can query the view for the sum.
SELECT total FROM table_with_sum where id=5;
The View does not store the sum for each row, the totalcolumn is computed every time you query the View. If your goal is to make your query more efficient, this will not help.
There is an other way: add the column to the table and create triggers for update and insert that update the total column every time a row is modified.
I have two scenario based questions here.
Question 1
Input Dataset
Col1
A
A
B
C
C
B
D
A
C
Output Dataset
Col1 Col2
A 1
A 2
A 3
B 1
B 2
C 1
C 2
C 3
D 1
Question2
Input data string
AA-BB-CC-DD-EE-FF (can be of any delimiter and string can have any length)
Output data string
string 1 -> AA
string 2 -> BB
string 3 -> CC
string 4 -> DD
Thanks & Regards,
Subhasree
Question 1: Can be solved with a transformer. Sort the data and use the lastrowingroup functionality.
For Col2 just create a counter as a stage variable and add 1 for each row - if reset it with a second stage variable if lastrowingroup is reached.
Aternatively you could use a rownumber column in SQL.
Question2: You have not provided enough information. Is string1 a column or row? If you do not know anything upfront about the structure (any delimiter) this will get hard...
Say I have a table called list, where there are items like these (the ids are random uuids):
id rank text
--- ----- -----
x 0 Hello
x 1 World
x 2 Foo
x 3 Bar
x 4 Baz
I want to maintain the property that rank column always goes from 0 to n-1 (n being the number of rows)---if a client asks to insert an item with rank = 3, then the pg server should push the current 3 and 4 to 4 and 5, respectively:
id rank text
--- ----- -----
x 0 Hello
x 1 World
x 2 Foo
x 3 New Item!
x 4 Bar
x 5 Baz
My current strategy is to have a dedicated insertion function add_item(item) that scans through the table, filter out items with rank equal or greater than that of the item being inserted, and increment those ranks by one. However, I think this approach will run into all sorts of problems---like race conditions.
Is there a more standard practice or more robust approach?
Note: The rank column is completely independent of rest of the columns, and insertion is not the only operation I need to support. Think of it as the back-end of a sortable to-do list, and the user can add/delete/reorder the items on the fly.
Doing verbatim what you suggest might be difficult or not possible at all, but I can suggest a workaround. Maintain a new column ts which stores the time a record is inserted. Then, insert the current time along with rest of the record, i.e.
id rank text ts
--- ----- ----- --------------------
x 0 Hello 2017-12-01 12:34:23
x 1 World 2017-12-03 04:20:01
x 2 Foo ...
x 3 New Item! 2017-12-12 11:26:32
x 3 Bar 2017-12-10 14:05:43
x 4 Baz ...
Now we can easily generate the ordering you want via a query:
SELECT id, rank, text,
ROW_NUMBER() OVER (ORDER BY rank, ts DESC) new_rank
FROM yourTable;
This would generate 0 to 5 ranks in the above sample table. The basic idea is to just use the already existing rank column, but to let the timestamp break the tie in ordering should the same rank appear more than once.
you can wrap it up to function if you think its worth of:
t=# with u as (
update r set rank = rank + 1 where rank >= 3
)
insert into r values('x',3,'New val!')
;
INSERT 0 1
the result:
t=# select * from r;
id | rank | text
----+------+----------
x | 0 | Hello
x | 1 | World
x | 2 | Foo
x | 3 | New val!
x | 4 | Bar
x | 5 | Baz
(6 rows)
also worth of mention you might have concurrency "chasing condition" problem on highly loaded systems. the code above is just a sample
You can have a “computed rank” which is a double precision and a “displayed rank” which is an integer that is computed using the row_number window function on output.
When a row is inserted that should rank between two rows, compute the new rank as the arithmetic mean of the two ranks.
The advantage is that you don't have to update existing rows.
The down side is that you have to calculate the displayed ranks before you can insert a new row so that you know where to insert it.
This solution (like all others) are subject to race conditions.
To deal with these, you can either use table locks or serializable transactions.
The only way to prevent a race condition would be to lock the table
https://www.postgresql.org/docs/current/sql-lock.html
Of course this would slow you down if there are lots of updates and inserts.
If can somehow limit the scope of your updates then you can do a SELECT .... FOR UPDATE on that scope. For example if the records have a parent_id you can do a select for update on the parent record first and any other insert who does the same select for update would have to wait till your transaction is done.
https://www.postgresql.org/docs/current/explicit-locking.html#:~:text=5.-,Advisory%20Locks,application%20to%20use%20them%20correctly.
Read the section on advisory locks to see if you can use those in your application. They are not enforced by the system so you'll need to be careful of how you write your application.
I'm using SSRS (VS2008) and creating a report of work orders. In the detail line of the report table, I have the following columns (with some fake data)
WONUM | A | B | Hours
ABC123 | 3 | 0 | 3
SPECIAL| 0 | 6 | 6
DEF456 | 5 | 0 | 5
GHI789 | 4 | 0 | 4
OTHER | 0 | 2 | 2
As you can kind of see, all work orders have a work order number (WONUM) as well as a total # of hours (HOURS). I need to put the hours into either column A or column B based on WONUM. I have a list of specifically named work orders (in the example, they would be "SPECIAL" and "OTHER") which would cause the HOURS value to be put in column B. If the WONUM is NOT a special named one, then it goes in column A. Here's what I WANTED to put as the expression for column A and column B:
Column A: =IIF(Fields!WONUM.Value IN ("SPECIAL","OTHER"), 0, Fields!Hours.Value)
Column B: =IIF(Fields!WONUM.Value IN ("SPECIAL","OTHER"), Fields!Hours.Value, 0)
But as you're probably aware, Fields!WONUM.Value IN ("SPECIAL","OTHER") is not a valid method of doing this! What is the best way to make this work? I cannot flag it in the SQL query in any other way for other reasons so it must be done in the table.
Thanks in advance for any and all help!
Try this, (Using InStr() function)
IIF(InStr(Fields!WONUM.Value,"SPECIAL")>0 OR InStr(Fields!WONUM.Value,"OTHER")>0, 0, Fields!Hours.Value)
IIF(InStr(Fields!WONUM.Value,"SPECIAL")>0 OR InStr(Fields!WONUM.Value,"OTHER")>0, Fields!Hours.Value,0)
If it's just the two WONUMs then you can do this:
Column A:
=IIF((Fields!WONUM.Value <> "SPECIAL") AND (Fields!WONUM.Value <> "OTHER"), Fields!Hours.Value, 0)
Column B:
=IIF((Fields!WONUM.Value = "SPECIAL") OR (Fields!WONUM.Value = "OTHER"), Fields!Hours.Value, 0)
or use the same formula in each column for consistency and swap the field/0 at the end.
I'm trying to find a way to use Perl to further process a PostgreSQL output. If there's a better way to do this via PostgreSQL, please let me know. I basically need to choose certain columns (Realtime, Value) in a file to concatenate certains columns to create a row while keeping ID and CAT.
First time posting, so please let me know if I missed anything.
Input:
ID CAT Realtime Value
A 1 time1 55
A 1 time2 57
B 1 time3 75
C 2 time4 60
C 3 time5 66
C 3 time6 67
Output:
ID CAT Time Values
A 1 time 1,time2 55,57
B 1 time3 75
C 2 time4 60
C 3 time5,time6 66,67
You could do this most simply in Postgres like so (using array columns)
CREATE TEMP TABLE output AS SELECT
id, cat, ARRAY_AGG(realtime) as time, ARRAY_AGG(value) as values
FROM input GROUP BY id, cat;
Then select whatever you want out of the output table.
SELECT id
, cat
, string_agg(realtime, ',') AS realtimes
, string_agg(value, ',') AS values
FROM input
GROUP BY 1, 2
ORDER BY 1, 2;
string_agg() requires PostgreSQL 9.0 or later and concatenates all values to a delimiter-separated string - while array_agg() (v8.4+) creates am array out of the input values.
About 1, 2 - I quote the manual on the SELECT command:
GROUP BY clause
expression can be an input column name, or the name or ordinal number
of an output column (SELECT list item), or ...
ORDER BY clause
Each expression can be the name or ordinal number of an output column
(SELECT list item), or
Emphasis mine. So that's just notational convenience. Especially handy with complex expressions in the SELECT list.