I need to use Oracle bitwise operation in my project. I know there is the BITAND() available for the purpose. As far as I know BITAND() is the only such operator and other operators such as bitwise OR operator can be derived from BITAND().
I also found that Oracle has another set of bitwise operators:
AND &
OR |
XOR ^
NOT ~
I thought to myself: why bother to derive the other operators from BITAND() instead of using this set of operators which are already available? The problem is that, by searching for examples, it is found that all the tech documents provide only the concepts, such as
15 & 9 yields 9 (1111 & 1001 = 1001)
15 | 9 yields 15 (1111 | 1001 = 1111)
15 ^ 9 yields 6 (1111 ^ 1001 = 0110)
but I haven't been able to find a single example of how these operators are used. I tried myself:
select 15 & 9 from dual;
only to find that & is not even recognized as a bitwise operator. Instead, I got prompted to provide a value for the &9 variable.
My questions are:
Can the &, |, ^, ~ operators be used in place of BITAND()?
If yes, how?
If not, why?
If the &, |, ^, ~ operators are for some different purposes, what are they used for and how are they used?
As far as I know, most of Oracle's bitwise functions are in UTL_RAW, where they're intended to be used for RAW datatypes. This is a bit cumbersome, but you could write your own wrapper functions pretty easily.
declare
x1 raw(10) := utl_raw.cast_from_binary_integer(15);
x2 raw(10) := utl_raw.cast_from_binary_integer(9);
raw_result raw(10);
result number;
begin
raw_result := utl_raw.bit_and(x1,x2);
result := utl_raw.cast_to_binary_integer(raw_result);
dbms_output.put_line('bit_and: ' || result);
raw_result := utl_raw.bit_or(x1,x2);
result := utl_raw.cast_to_binary_integer(raw_result);
dbms_output.put_line('bit_or: ' || result);
raw_result := utl_raw.bit_xor(x1,x2);
result := utl_raw.cast_to_binary_integer(raw_result);
dbms_output.put_line('bit_xor: ' || result);
end;
/
Sounds like kfinity's answer is the way to go, but for the sake of argument, this Ask Tom article shows examples for all but bitnot. Perhaps it could help someone.
select bitand(15,9) bitand,
(15 + 9) - bitand(15,9) bitor,
(15 + 9) - BitAND(15,9) * 2 bitxor
from dual;
BITAND BITOR BITXOR
---------- ---------- ----------
9 15 6
1 row selected.
I'd love to see a way to do bitnot.
SQL> select BitAnd(15, 9) from dual;
BITAND(15,9)
------------
9
SQL>
The list of Oracle's Bit/Binary Functions is here: https://docs.oracle.com/cd/E41183_01/DR/Bit_Binary_Functions.html
Related
As an illustrative example, suppose this is your dataset:
cat sex age
1 1 13
1 0 14
1 1 .
2 1 23
2 1 45
2 1 15
If you want to create a table of frequencies between cat and sex, you tabulate these two variables and you get the following result:
tab cat sex
| sex
cat | 0 1 | Total
-----------+----------------------+----------
1 | 1 2 | 3
2 | 0 3 | 3
-----------+----------------------+----------
Total | 1 5 | 6
I am writing a Stata program where the three variables are involved, i.e. cat, sex and age. Getting the matrix of frequencies for the first two variables is just an intermediate step that I need for further computation.
cap program drop myexample
program def myexample, rclass byable(recall) sortpreserve
version 14
syntax varlist [aweight iweight fweight] [if] [in] [ , AGgregate ]
args var1 var2 var3
tempname F
marksample touse
set more off
if "`aggregate'" == "" {
local var1: word 1 of `varlist'
local var2: word 2 of `varlist'
local var3: word 3 of `varlist'
qui: tab `var1' `var2' [`weight' `exp'] if `touse', matcell(`F') label matcol(`var2')
mat list `F'
}
end
However, when I run:
myexample cat sex age
I get this result which is not what I expected:
__000001[2,2]
c1 c2
r1 1 1
r2 0 3
That is, given that age contains a missing value, even if it is not directly involved in the tabulation, the program ignores the missing value and does not take into account that observation. I need to get the result of the first tabulation. I have tried using summarize instead, but the same problem arises. When implemented inside the program, missing values are not counted.
You are complaining about behaviour which you built into your own program. The responsibility and the explanation are in your hands.
The effect of
marksample touse
followed by calling up a command with the qualifier
if `touse'
is to ignore missing values. marksample by default marks as "to use" those observations in which all variables specified have non-missing values; the other observations are marked as to be ignored. It also takes account of any if or in qualifiers and any zero weights.
It's also true, as #Noobie explains, that omitting missing values from a tabulation is default for tabulate in any case.
So, to get the result you want you'd need to modify your marksample call to
marksample touse, novarlist
and to call up tabulate with the missing option (if it's compulsory) or to allow users to specify a missing option which you then pass to tabulate.
You also ask about summarize. By design that command ignores missing values. I don't know what you would expect summarize to do about them. It could report a count of missing values. If you want that, several other commands will oblige, such as codebook or missings (Stata Journal). You can always include a report on missings in your program, such as using count to count the missings and display the result.
I understand your program to be very much work in progress, so won't comment on details you don't ask about.
This is caused by marksample. Rule 5 in help mark states
The marker variable is set to 0 in observations for which any of the
numeric variables in varlist contain a numeric missing value.
You should use the novarlist option. According to the help file,
novarlist is for use with marksample. It specifies that missing values
among variables in varlist not cause the marker variable to be set to 0.
if I understand well you want tab to include missing values? If so, you just have to ask for it
tab myvar1 myvar2, mi
from the documentation
missing : treat missing values like other values
The question sounds easy because only need a substring (name,1,1). But in the Hungarian language there are many letter wich contains multicharacter. eg : CS,DZ,DZS,LY,NY,SZ,TY,ZS
IF v_type='by_name' THEN
select DISTINCT name
into v_result
from my_table
where instr(_START_LETTERS_,substr(upper(v_name),1,1))>0 and ZIPCODE = v_act_zipcode;
return v_result;
and my table eg:
zipcode name _START_LETTERS
1234 Ryan A,B,C
1234 Bryan CS,D
And if i want to get my name CSanád i need to get CS not the first char C-> becuase i will get multirow exception.
Do you have anysuggestion to use get the first lettor? Or I have to write a huge if-else/case structure to make my code awful and impenetrable.
Thanks
I think the most straight-forward solution is to write a stored function that extracts the first letter:
create function hun_first_letter(name in varchar2) return varchar2 as
begin
if substr(upper(name),1,3) in ('DZS') then
return substr(name,1,3);
elsif substr(upper(name),1,2) in ('CS','DZ','LY','NY','SZ','TY','ZS','GY') then
return substr(name,1,2);
else
return substr(name,1,1);
end if;
end;
Try to replace substr(upper(v_name), 1, 1) with:
regexp_substr(upper(v_name), '^[[:alpha:][.cs.][.xx.][.yy.]]', 1, 1, 'i')
where
[:alpha:] is a special function (any letter) - actually, I don't know, maybe this function alone can find collating sequences (depending on NLS)
[.cs.] is an example of a collating sequence;
[.xx.], [.yy.] - other collating sequences possible in your NLS
So the regexp_substr above tries to find any letter OR 'cs' OR 'xx' OR 'yy' and etc.
It starts searching from position = 1 and returns occurance = 1. Finally, the search is case insentitive ('i')
But first of all you may check whether this function:
regexp_substr(upper(v_name), '^[[:alpha:]]', 1, 1, 'i')
would find your collating sequences (I'd be glad to know this)
Is it possible to use DECODE on a SUM field ?
For example, something like this :
DECODE( SUM("QTA' CONV SUM 1 2 2"),'>0',1,'=0',0)
In your specific case, where you want the result to be 1 if the SUM is greater than zero or 0 if the SUM is zero, you can use the Oracle SIGN function. I'm not sure if there's any special Discoverer syntax, but outside of Discoverer I'd do it something like this:
SIGN(SUM(whatever you're summing))
The "techonthenet" site documents the function here.
An alternative to #EdGibbs, if the values that you're summing are integers:
Greatest(Sum(...),1)
If you had negatives to contend with then maybe:
Least(Greatest(Sum(...),1),0)
The syntax gets a bit gnarly so if you did want to stick with Decode or Case then:
Case Sum(...)
When 0 Then 0
Else 1
End
... or ...
Decode(Sum(...),0,0,Sum(...))
I wouldn't go for a solution that repeats the Sum() though. Keep it DRY
I'm having a problem when I use these 2 FOR to initialize a two dimensional vector/array:
I have these types defined:
type
Range9 = 0..8;
Digit = '0'..'9';
Board = array [Range9,Range9] of Digit;
and then the part of the code where there are problems with the FOR's is the following:
var
i : Range9;
j : Range9;
table : Board;
BEGIN
for i:=0 to 8 do begin
for j:=0 to 8 do begin
table[i,j] := '0'
end
end;
END.
Now the problem is that, when I debug this portion of code, for some reason, my i variable is modified when it's not supposed to.
For example, I have a watch on i and j and if I put a breakpoint in the line table[i,j] := 0
I see with the watches these values:
i j
0 0
256 1
512 2
768 3
1024 4
1280 5
1536 6
1792 7
2048 8
2049 8
1 0
257 1
513 2
769 3
and so on...
So, when the program enters in the second for (the one that increases the j) my i increases in intervals of 256... I really don't know why is this happening.
And another thing I discovered is that, the problem solves if I change the TYPE of the i variable.
If in the VAR section I put i : integer instead of i : Range9, i doesn't get modified when isn't supposed to.
I would really appreciate if someone explains me why is happening this.
I've found the answer to my own question... well, I didn't exactly found the answer, I've asked this same question in the forum board of the programming course I'm attending and one of the professors gave me this link:
(it's in spanish btw)
http://www.fing.edu.uy/inco/cursos/prog1/pm/field.php/FAQ/Laboratorio#toc17
A quick translation:
This happens with variables defined as subranges. The reason isn't sure; but without doubt is an implementation error of the debugger. There is a 'trick' that can work to solve this (although not always), to be able to see the correct values on the debugger:
Suppose that you have the following variable in your program:
var anything: 1 .. 10;
Add in your program a integer variable which won't be used in any part of the program:
var anything: 1..10;
aux: integer; { only for the debugger }
Then when you define the debugger watch, instead of adding the anything variable, you should add the following expression:
aux:= anything
The aux variable can be used to view different variables, so you only need to declare one aux variable.
In some cases, the previous may not work. Another solution is to change the type of all the variables defined with subranges to integer, char, string, etc (depending the case) only for debug and the change it back again.
end of the translation.
Hope this will be useful for someone else facing the same error.
BTW, this happens with the debugger of free pascal IDE 2.2.2 , maybe in another IDE/compiler/debugger of pascal it doesn't happen.
I haven't done Pascal in a while, so I might be a bit rusty. The only thing I can think of that is creating your problem is that you created a character range that was interpreted as a byte array, which was then converted to a Digits and then multiplied, which gave you those weird values. But, I could be wrong. I am unfamiliar with FreePascal.
Type
Range9 = 0..8
Board = Array[Range9,Range9] of Integer;
var
A : Board;
I,J : Integer;
begin
For I:=0 to 8 do
For J:=0 to 8 do
A[I,J]:=I*J;
end.
Reference: ftp://ftp.freepascal.org/pub/fpc/docs-pdf/ref.pdf
I posted this earlier and it got closed because I did not show my try at coding it, so here is the question:
SECTIONS
$160 = section 1
$220 = section 2
$280 = section 3
$350 = section 4
$425 = section 5
Develop pseudocode that accepts as input the name of an unspecified number of masqueraders who each have paid the full cost of their costume and the amount each has paid.
A masquerader may have paid for a costume in any of the five sections in the band. The algorithm should determine the section in which the masquerader plays, based on the amount he/she has paid for the costume. The algorithm should also determine the number of masqueraders who have paid for costumes in each section.
The names of persons and the section for which they have paid should be printed. A listing of the sections and the total number of persons registered to play in each section should also be printed, along with the total amount paid in each section.
Here is my try at it: *Note this is programmed in Pascal, and I need help fixing it up and finishing it. Please help and thanks again.
program Masqueraders;
uses
WinCrt; { Allows Writeln, Readln, cursor movement, etc. }
const
MAX = 5; {this determine the amount of masquarader entered}
Type
listname = Array[1..MAX] of string;
listsect = Array[1..MAX] of string;
var
names : listname;
sections : listsect;
i, amount, TotalMas, TotalAmt, c1, c2, c3, c4, c5, amt1, amt2, amt3, amt4, amt5 : integer;
begin
amount := 1;
while amount <> 0 do
begin
i := i + 1;
readln(names[i]);
readln(amount);
if(amount = 160) then
begin
c1 := c1 + 1; {Count the number of persons for section 1}
amt1 := amt1 + amount; {accumulate the amount for section 1}
sections[i] := 'Section 1';
end;
if(amount = 220) then
begin
c2 := c2 + 1; {Count the number of persons for section 1}
amt2 := amt2 + amount; {accumulate the amount for section 1}
sections[i] := 'Section 2';
end; {end the IF for section 2}
if(amount = 280) then
begin
c3 := c3 + 1; {Count the number of persons for section 1}
amt3 := amt3 + amount; {accumulate the amount for section 1}
sections[i] := 'Section 3';
end; {end the IF for section 3}
if(amount = 350) then
begin
c4 := c4 + 1;
amt4 := amt4 + amount;
sections[i] := 'Section4';
end; {end If for section 4}
if (amount = 425) then
begin
c5 := c5 + 1;
amt5 := amt5 + amount;
sections[i] := 'Section5';
end;{end the while loop}
TotalMas := c1 + c2 + c3;
TotalAmt := amt1 + amt2 + amt3;
writeln('Name Section'); {Heading for the output}
for i := 1 to MAX do
begin
write(names[i]);
writeln(' ',sections[i]);
end;
writeln('Section 1: ');
write('Masquader: ', c1);
write('Amount: ', amt1);
writeln('Total Number of Masquarader: ', TotalMas);
writeln('Total Amount Paid by masquarader: ', TotalAmt);
end;
end.
In short, it should accept an undefined number of people and assign them to their respective sections based on the amount of money they entered, then calculate the number of people in each section. This is my current output:
Name John Money=160 Section 1
Name Keith Money=220 Section John
This is what I want:
Name John Money=160 Section1
Name Keith Money=220 Section2
I'm not really familiar with Pascal so I can't tell you how to fix this but one issue I notice is that your code seems to violate the "DRY" rule: Don't Repeat Yourself. The code inside each if amt = xxx block looks almost exactly the same, so is there a way you can write that code once, and then call your code with different parameters each time? Something so that you're not rewriting the same code five times.
Here's are a few hints to improve your code:
Do you think there might be a way to print "Section {i}" in your final loop without looking it up using sections[i], thereby negating the need for the array completely?
How could you build this so that adding a section 6 wouldn't require modifications to your code?
listname and listsect are awfully similar, what modifications to your code could you do to eliminate the need to have two identical definitions?
What happens if the user enters 0 for the amount the third time they are prompted?
Note: one of these hints should point you directly to the source of your problem.
Here are the problems I see:
The requirements say an "unspecified number of masqueraders" but you have set the max to 5. You can't store the list of names in a fixed size array if there are possibly going to be more than 5 masqueraders. As is, the app may either crash or corrupt memory (depending on the version of Pascal you're using) when user enters the 6th masquerader. If you are allowed to print the masquerader's Name and Section immediately after it is input, then you should print that right after the user inputs the Name and Amount (not after the input while loop). However, if it is required that you print the list of Names and Sections after all input, then you need to store the Name+Section in a variable length data structure like a linked list or even simpler a string.
The variables c1 to c5 and amt1 to amt5 would be better declared as two arrays (c and amt) of 1..MAX instead of 10 variables. When user inputs the amount, use it determine the section number which then can be used as the index into the c and amt arrays.
Not sure what implementation of Pascal you're using but it would be safer to initialize all variables before use otherwise they could contain unpredictable values.
The sections array is unnecessary. All it ends up containing is the title of the section which doesn't need to be calculated or stored.
If you used a repeat/until loop instead of a while loop, it would avoid the slightly kludgy "amount := 1" initialization at the top to enter the while loop. The repeat/until would be until Amount = 0.
TotalMas is only adding c1 to c3 (what about c4 and c5)?
TotalAmt is only adding amt1 to amt3 (what about amt4 and amt5)?
The for-loop to print the names and section is completely wrong, see points 1 and 4.
Hope this helps and let me know if you need clarification on any points.
My gripes with this code:
1) The variable names stink. Virtually all of them are way too short, they do not communicate what they do.
2) The wrong loop control structure is used here.
3) I see virtually identical code repeated 5 times. This is simply crying out for arrays.
4) The comments explain what you are doing, not why you are doing it. Half of them are virtually completely useless, if you're going to comment an end you should simply comment it with the identity of whatever it's an end to. end; //if I see only one comment that even tries to explain why and you've got it wrong as you're mixing up people with sections.
5) Your sections array accomplishes nothing useful. The assignments to the values are always fixed and thus there is no reason to store them at all--if you need the labels you can create them at print time.
6) You are assuming there are only going to be 5 people. That's not given in the problem--there's 5 sections.