I am seeking to combine the results of two columns, and view it in a single column:
select description1, description2 from daclog where description2 is not null;
results two registry:
1st row:
DESCRIPTION1
Initialization scans sent to RTU 1, 32 bit mask: 0x00000048. Initialization mask bits are as follows: B0 - status dump, B1 - analog dump B2 - accumulator dump, B3 - Group Data Dump, B4 - accumulat
(here begin DESCRIPTION2)
,or freeze, B5 - power fail reset, B6 - time sync.
2nd row:
DESCRIPTION1
Initialization scans sent to RTU 1, 32 bit mask: 0x00000048. Initialization mask bits are as follows: B0 - status dump, B1 - analog dump B2 - accumulator dump, B3 - Group Data Dump, B4 - accumulat
(here begin DESCRIPTION2)
,or freeze, B5 - power fail reset, B6 - time sync.
Then I need the value of description1 and description2, on the same column.
It is possible?
Thank you!
You can combine two columns into one by using || operator.
select description1 || description2 as description from daclog where description2 is not null;
If you would like to use some substrings from each of the descriptions, you can use String functions and then combine the results. FNC(description1) || FNC(descriptions2) where FNC might be a function to return the desired substring of your columns.
Related
I am new to GAMS and I have a table data which has 3 rows and 6 columns. I want to pull each row and use its data for two parameters(pull each row which has 6 element and use the first three elements for one parameter and the other three elements for the second parameter) using loop or for statement. i tried to use both of them but for the loop i received zero value for my parameter which is incorrect and for the for statement i received some errors.
this is my code for the first row which both 'loop' and 'for' are used (i used them separately each time but for show what was my code i just wrote them together).
Please help me.
Thanks
scalars j;
sets
o /red,green,blue/
p /b1,b2,b3,p1,p2,p3/
k /1*3/;
Table sup(*,*)
b1 b2 b3 p1 p2 p3
red 12 15 20 200 50 50
green 16 17 0 150 50 0
blue 13 18 0 100 50 0 ;
parameters Bid_Red(k),Pmax_Red(k),t;
*for statement***************
for(j= 1 to 3,
t=card(o)+j;
Bid_Red(k)$( ord(k) = j )=sup('red',j);
Pmax_Red(k)$( ord(k) = j )=sup('red',t);
);
*loop statement***************
t=card(o);
loop(k,
Bid_Red(k)=sup('red',k);
Pmax_Red(k)=sup('red',k+t);
);
display Bid_red, Pmax_Red
One of the core features of GAMS is how it deals with set structures and indexing. I'd recommend looking at the excellent documentation, for example on set definition https://www.gams.com/latest/docs/UG_SetDefinition.html, to really get a feel for how to get the best out of it.
In your case, you can proceed as follows. p is a set. Create some subsets of it p_ and b_, given by the syntax subset_name(set_name).
sets p_(p) / p1, p2, p3 /,
b_(p) / b1, b2, b3 /;
Create parameters over appropriate dimensions (i.e. the full set), and define them over the subset you are interested in:
parameters bid_red(o,p),pmax_red(o,p);
bid_red(o,b_) = sup(o,b_);
pmax_red(o,p_) = sup(o,p_);
Then display bid_red, pmax_red; gives:
---- 21 PARAMETER bid_red
b1 b2 b3
red 12.000 15.000 20.000
green 16.000 17.000
blue 13.000 18.000
---- 21 PARAMETER pmax_red
p1 p2 p3
red 200.000 50.000 50.000
green 150.000 50.000
blue 100.000 50.000
If you do want to select individual rows, you can use e.g. pmax_red('red',p_) in your code. This is essentially just a special case of subsetting in which the subset is of size 1.
I am trying to fill column D and column E.
Column A: varchar(64) - unique for each trip
Column B: smallint
Column C: timestamp without time zone (excel messed it up in the
image below but you can assume this as timestamp column)
Column D: numeric - need to find out time from origin in minutes
column E: numeric - time to destination in minutes.
Each trip has got different intermediate stations and I am trying to figure out the time it has been since origin and time to destination
Cell D2 = C2 - C2 = 0
cell D3 = C3 - C2
Cell D4 = C4 - C2
Cell E2 = E6 - E2
Cell E3 = E6 - E3
Cell E6 = E6 - E6 = 0
The main issue is that each trip contains differnt number of stations for each trip_id. I can think about using partition by column but cant figure out how to implement it.
Another sub question: I am dealing with very large table (100 million rows). What is the best way Postgresql experts implement data modification. Do you create like a sample table from the original data and implement everything on the sample before implementing the modifications on the original table or do you use something like "Begin trasaction" on the original data so that you can rollback in case of any error.
PS: Help with question title appreciated.
you don't need to know the number of stops
with a as (select *,extract(minutes from c - min(c) over (partition by a)) dd,extract(minutes from max(c) over (partition by a) - c) ee from td)
update td set d=dd, e=ee
from a
where a.a = td.a and a.b=td.b
;
http://sqlfiddle.com/#!17/c9112/1
everyone
I would like to ask community of help to find a way of how to cache our huge plain table by splitting it to the multiple hashes or otherwise.
The sample of table, as an example for structure:
A1 B1 C1 D1 E1 X1
A1 B1 C1 D1 E1 X2
A7 B5 C2 D1 E2 X3
A8 B1 C1 D1 E2 X4
A1 B6 C3 D2 E2 X5
A1 B1 C1 D2 E1 X6
This our denormalized data, we don't have any ability to normalize it.
So currently we must perform 'group by' to get required items, for instance to get all D* we perform 'data.GroupBy(A1).GroupBy(B1).GroupBy(C1)' and it takes a lot of time.
Temporarily we had found workaround for this by creating composite a string key:
A1 -> 'list of lines begin A1'
A1:B1 -> 'list of lines begin A1:B1'
A1:B1:C1 -> 'list of lines begin A1:B1:C1'
...
as a cache of results of grouping operations.
The question is how it can be stored efficiently?
Estimated number of lines in denormalized data around 10M records and as in my an example there is 6 columns it will be 60M entries in hash. So, I'm looking an approach to lookup values in O(N) if it's possible.
Thanks.
Most files I am working with only have the following fields:
F00001 - usually 1 (f1) or 9 (f9)
K00001 - usually only 1-3 sub-fields of
zoned decimals and ebcdic
F00002 - sub-fields of ebcdic, zoned and
packed decimals
Occasionally other field names K00002, F00003 and F00004 will appear in cross reference files.
Example Data:
+---------+--------------------------------------------------+--------------------------------------------------------------------------------------------+
| F00001 | K00001 | F00002 |
+---------+--------------------------------------------------+--------------------------------------------------------------------------------------------+
| f1 | f0 f0 f0 f0 f1 f2 f3 f4 f5 f6 d7 c8 | e2 e3 c1 c3 d2 d6 e5 c5 d9 c6 d3 d6 e7 40 12 34 56 7F e2 d2 c5 c5 e3 |
+---------+--------------------------------------------------+--------------------------------------------------------------------------------------------+
Currently using:
SELECT SUBSTR(HEX(F00001), 1, 2) AS FNAME_1, SUBSTR(HEX(K00001), 1, 14) AS KNAME_1, SUBSTR(HEX(K00001), 15, 2) AS KNAME_2, SUBSTR(HEX(K00001), 17, 2) AS KNAME_2, SUBSTR(HEX(F00002), 1, 28) AS FNAME_2, SUBSTR(HEX(F00002), 29, 8) AS FNAME_3, SUBSTR(HEX(F00002), 37, 10) AS FNAME_4 FROM QS36F.FILE
Is this the best way to unpack EBCDIC values as strings?
You asked for 'the best way'. Manually fiddling the bytes is categorically NOT the best way. #JamesA has a better answer: Externally describe the table and use more traditional SQL to access it. I see in your comments that you have multiple layouts within the same table. This was typical years ago when we converted from punched cards to disk. I feel your pain, having experienced this many times.
If you are using SQL to run queries, I think you have several options, all of which revolve around having a sane DB2 table instead of a jumbled S/36 flat file. Without more details on the business problem, all we can do is offer suggestions.
1) Add a trigger to QS36F.FILE that will break out the intermingled records into separate SQL defined tables. Query those.
2) Write some UDFs that will pack and unpack numbers. If you're querying today, you'll be updating tomorrow and if you think you have some chance of maintaining the raw HEX(this) and HEX(that) for SELECTS, wait until you try to do an UPDATE that way.
3) Write stored procedures that will extract out the bits you need for a given query, put them into SQL tables - maybe even a GLOBAL TEMPORARY TABLE. Have the SP query those bits and return a result set that can be consumed by other SQL queries. IBM i supports user defined table functions as well.
4) Have the RPG team write you a conversion program that will read the old file and create a data warehouse that you can query against.
It almost looks as if old S/36 files are being accessed and the system runs under CCSID 65535. That could cause the messy "hex"representation issue as well as at least some of the column name issues. A little more info about the server environment would be useful.
I'm trying to read a file into memory in a Fortran program. The file has N rows with two values in each row. This is what I currently do (it compiles and runs, but gives me incorrect output):
program readfromfile
implicit none
integer :: N, i, lines_in_file
real*8, allocatable :: cs(:,:)
N = lines_in_file('datafile.txt') ! a function I wrote, which works correctly
allocate(cs(N,2))
open(15, 'datafile.txt', status='old')
read(15,*) cs
do i=1,N
print *, cs(i,1), cs(i,2)
enddo
end
What I hoped to get was the data loaded into the variable cs, with lines as first index and columns as second, but when the above code runs, it first gives prints a line with two "left column" values, then a line with two "right column" values, then a line with the next two "left column values" and so on.
Here's a more visual description of the situation:
In my data file: Desired output: Actual output:
A1 B1 A1 B1 A1 A2
A2 B2 A2 B2 B1 B2
A3 B3 A3 B3 A3 A4
A4 B4 A4 B4 B3 B4
I've tried switching the indices when allocating cs, but with the same results (or segfault, depending on wether I also switch indices at the print statement). I've also tried reading the values row-by-row, but because of the irregular format of the data file (comma-delimited, not column-aligned) I couldn't get this working at all.
How do I read the data into memory the best way to achieve the results I want?
I do not see any comma in your data file. It should not make any difference with the list-directed input anyway. Just try to read it like you write it.
do i=1,N
read (*,*) cs(i,1), cs(i,2)
enddo
Otherwise if you read whole array in one command, it reads it in column-major order, i.e., cs(1,1), cs(2, 1), ....cs(N,1), cs(1, 2), cs(2,2), ... This is the order in which the array is stored in memory.