I am trying to check if an entry is already in the database and add the entry if it isn't but the if statement never runs even though the condition is met.
userCurs.execute("SELECT EXISTS(SELECT 1 FROM images WHERE imageLink=?)", (image,))
exists = userCurs.fetchone()
if exists is None:
addImage(userName,image,'','')
else:
print '--------> image skipped'
print userCurs.fetchone()
I get this output:
--------> image skipped
None
--------> image skipped
None
and no entries are made to the database
The SQL statement:
SELECT EXISTS(SELECT 1 FROM images WHERE imageLink=?)
will always return a single row. The value of the column in that row will be the result of the EXISTS() function, which will be TRUE if any matches are found, or FALSE otherwise.
Since your original code only tested for the existence of a row in the result, and the full statement will always return exactly one row, you get the behavior you see.
What I think you should do is have your query return a rowset that has zero rows if no matches are found, and one (or more) rows if matches are found:
userCurs.execute("SELECT 1 FROM images WHERE imageLink=?", (image,))
Now your original test should work - if no imageLinks match the query, then there will be no rows in the result, so the first fetchone() will return a null object as you expect.
Of course, as several others have mentioned, you should ony call fetchone() once per row since it moves the cursor.
Solved it by changing the code to
userCurs.execute("SELECT EXISTS(SELECT 1 FROM images WHERE imageLink=?)", (image,))
exists = userCurs.fetchone()
if exists[0] == 0:
addImage(userName,image,'','')
else:
print '--------> image skipped'
print exists
As people have said the calling fetchone() twice gives different results the actual value of exists was (0,)
Don't call cursor.fetchone() again; the next row is always empty. Reuse the variable. You are fetching a (0,) or (1,) tuple; you could use tuple assignment to extract the flag value (note the comma on exits, =):
exists, = userCurs.fetchone()
if not exists:
addImage(userName, image, '', '')
else:
print '--------> image skipped'
print exists
Now exists will be set to 0 or 1, rather than (0,) or (1,) and the if not exists: test will not pass for the 0 case.
Related
I would like to create a trigger with I can check the uploaded data and I can insert into another table as well. In the initial table (capture) I have 15 columns, but I would like to transfer only 5 columns (ring_number, code, year, date, species, location) to another table (ring).
The ring table is a background table in which I am collecting the combinations of ring_number and code, more specifically one ring_number could be paired only with one code. There is one exception, when the code include "X", than it can be changed later, and in this case this code can be paired with more ring_number, and if originally belongs to the ring_number a code with "X" it can be changed later.
In the capture table, could be possible to upload the same combination of code and ring_number multiple times with a condition of a third column. But still the ring_number can be paired only with one code, with exceptions of codes included "X". The name of the conditional column is recapture. If recapture (boolean column type) is "true", then you can upload the combination of code and ring_number again. If it is "empty" or "no" you can upload only new combinations of code and ring_number. If somebody uploads old combinations then the following error message has to raise: this combination already exists, please check your data and if it is a recapture, then set the recapture column to yes.
Additionally: ring_number is a not null column, but code can be empty. And different ring_number can be paired with empty code than later can be paired with actual value.
I have several problems with my code:
1: I would like to define the exception to X with regex, and the X can be anywhere in the code. But can not manage the regex in a good way. It does just not work.
2: I write conditional checkpoint with recapture column and if I have an old combination this is work on the right way and say please set the recapture column to yes. But! If I set the recapture column to yes I get the same error message.
Could you help to solve these issues?
Here is my code:
Declare
a integer := 0;
b integer := 0;
c integer := 0;
d integer := 0;
Begin
IF new.code <> '' THEN
--Az 'a' means whether the given ring_number already exist in the database with a code, which is not empty
SELECT INTO a COUNT(*) FROM plover_captures PC WHERE PC.ring_number = new.ring_number AND PC.code <> new.code AND PC.code <> '' AND PC.code ~ '[X]{2}[\.]{1}[X]{2}[|]{1}[X]{2}[\.]{1}[X]{2}';
--Az 'b' means the given code already exist in the database with a ring_number
SELECT INTO b COUNT(*) FROM plover_captures PC WHERE PC.ring_number <> new.ring_number AND PC.code = new.code AND PC.code ~ '[X]{2}[\.]{1}[X]{2}[|]{1}[X]{2}[\.]{1}[X]{2}';
--Az 'c' how much times exist the given ring_number with the given code in the database
SELECT INTO c COUNT(*) FROM plover_captures PC WHERE PC.ring_number = new.ring_number AND PC.code = new.code AND PC.code ~ '[X]{2}[\.]{1}[X]{2}[|]{1}[X]{2}[\.]{1}[X]{2}';
--Az 'd' means the given combination already exist in ring table or not
SELECT INTO d COUNT(*) FROM plover_rings PC WHERE PC.ring_number = new.ring_number AND PC.code = new.code;
IF a > 0 THEN
raise exception 'This ring_number is already paired with another code before. %', new.ring_number;
END IF;
IF b > 0 THEN
raise exception 'This code is already paired with another ring_number before. %', new.code;
END IF;
IF c > 0 AND (new.rettrap IS null OR new.rettrap IS false) THEN
raise exception 'This ring_number and code pair is already in the database. So it is a rettrap but the rettrap attribute set to false or null. %, %, %', new.ring_number, new.code, new.rettrap;
END IF;
IF c = 0 AND new.rettrap IS true THEN
raise exception 'The rettrap attribute set to true but this ring_number and code pair is not in this database yet. %, %, %', new.ring_number, new.code, new.rettrap;
END IF;
IF c = 0 AND d = 0 THEN
Insert into plover_rings values(new.ring_number,new.code,new.species,new.location,new.year, new.date);
END IF;
END IF;
Return new;
End
I'm trying to impute missing values in a dataframe df. I have a column A with 300 NaN's. I want to randomly set 2/3rd of it to value1 and the rest to value2.
Please help.
EDIT: I'm actually trying to this on dask, which does not support item assignment. This is what I have currently. Initially, I thought I'll try to convert all NA's to value1
da.where(df.A.isnull() == True, 'value1', df.A)
I got the following error:
ValueError: need more than 0 values to unpack
As the comment suggests, you can solve this with Series.where.
The following will work, but I cannot promise how efficient this is. (I suspect it may be better to produce a whole column of replacements at once with numpy.choice.)
df['A'] = d['A'].where(~d['A'].isnull(),
lambda df: df.map(
lambda x: random.choice(['value1', 'value1', x])))
explanation: if the value is not null (NaN), certainly keep the original. Where it is null, replace with the corresonding values of the dataframe produced by the first lambda. This maps values of the dataframe (chunks) to randomly choose the original value for 1/3 and 'value1' for others.
Note that, depending on your data, this likely has changed the data type of the column.
When printing row in a csv file, how do you get it to iterate over the entire csv instead of one line at a time when performing an if statement? For example:
import csv
nameid = raw_input("ID please")
with open('cards.csv', 'rb') as csvfile:
reader = csv.reader(csvfile, delimiter=',')
for row in reader:
row = list(row)
if nameid == row[0]:
print row
else:
print "sorry"
with this csv:
101,8
102,10
103,5
104,0
will use only the first line, then the second line, and so on, giving me a false statement 3 out of 4 times. So if I search for "102" in my raw_input, it will print:
"sorry"
['102', '10']
"sorry"
"sorry
You're actually very close to your intended functionality. You don't want to print "sorry" for every line that doesn't match, so you don't want that else block where it is. But you do want to print "sorry" if nothing at all in the file matches. As it turns out, you can just scoot that else block over one level to the left and have it correspond to the for block instead of the if. You'll also need one extra line:
import csv
nameid = raw_input("ID please")
with open('cards.csv', 'rb') as csvfile:
reader = csv.reader(csvfile, delimiter=',')
for row in reader:
row = list(row)
if nameid == row[0]:
print row
break
else:
print "sorry"
Now the else block is only triggered if the for block runs to completion (more info on this syntax here). To make sure it only runs to completion if there are no matches, add the break to immediately exit the loop when you see a match.
It's not giving you a false statement each time. You are iterating through the csv and checking every row's first element against the input. If it doesn't match, you print 'sorry'. If it does, you print the row.
If you want to only print a 'sorry' message if no matches are found, get rid of your else clause. Instead, set a boolean flag that gets initialized as false and only set to true when a match is found. After your iteration is complete, only print the 'sorry' message if the boolean is still false.
Okay, so I just recently got into lua and find myself stuck with the following:
I have the function peripheral.getNames() (which is a custom function)
it will return a table with the structure key,value, whereas key is always a number and starts from 1 and value will be what the function finds (it searches for devices connected to it)
In my example it creates a table which looks like this
1 herp
2 derp
3 monitor_1
4 morederp
I can print the values with the following
local pgn = peripherals.getNames()
for key,value in pairs(pgn) do
setCursorPos(1,key)
write(value)
end
end
this will output the corresponding value of the table at key on my display like this
herp
derp
monitor_1
morederp
now, I try to filter my results so it only prints something if value contains 'monitor'
I tried to achive this with
for key,value in pairs(pgn) do
if string.match(value, monitor) then
#dostuff
end
end
but it always returns 'bad argument: string expected, got nil'
so obviously string.match either does not accept 'value' or, value is not a string
so i tried converting value first
for key,value in pairs(pgn) do
value = tostring(value)
if ....
#dostuff
end
end
but it still throws the same error
Do any of you have an idea how i might either get string.match to accept 'value' or if there is another method to check the contents of 'value' for a pattern while in this for loop?
The error message is talking about the variable monitor, which is not defined and so has a nil value.
Try string.match(value, "monitor").
How would I do:
FinancialStatements.objects.get(statement_id=statement_id)
or SalesStatements.objects.get(statement_id=statement_id)
The result will always yield one result.
I ended up using the try/except route here:
try:
statement_object = FinancialStatements.objects.get(statement_id=statement_id)
except FinancialStatements.DoesNotExist:
statement_object = SalesStatements.objects.get(statement_id=statement_id)
Why not simply do:
result = (FinancialStatements.objects.filter(statement_id=statement_id) or
SalesStatements.objects.filter(statement_id=statement_id))
This should work, because filter returns a list - and an empty list if no entries match. An empty list evaluates to false in python's boolean logic, e.g. try running:
print [] or "hello"
(Just as a check, compare print ["Hi"] or "hello")
So, if the first query returns empty, the second will then be run. However, if the first matches anything, this will be result and the second query will be ignored.
Addendum: result will then be of a list type - you'll need to extract the (one and only) element with result[0].