I had trouble with selecting TEXT data type padded with zeros in front.
Found out there's something wrong with my DB.
My multiple tries and all of answers by peers should all should work.
Thanks #snakecharmerb and #forpas for pointing out for possible flaw in DB.
For example, code column includes
000001, 000010, 000300 ...
There are also a multiple of Data with same code.
code date
000030 20210101
000030 20210102
000030 20210103
000030 20210104
000030 20210105
...
I need to loop through a list so I tried multiple ways of using f-string, but it did not work.
con = sqlite3.connect("DIRECTORY")
cur = con.cursor()
code = '000030' // does not work
code = 000030 // forbidden by python 3.7
query = cur.execute(f"SELECT * From TABLE where code is {code}") // should work
query = cur.execute(f"SELECT * From TABLE where code is '{code}'") // should work
query = cur.execute(f'SELECT * From TABLE where code is "{code}"') // should work
query = cur.execute('SELECT * From TABLE where code = ?',('000030',)) // should work
query = cur.execute("SELECT * From TABLE where code is 000030") // works but cannot loop through a list
Also tried replacing 'is' with '=', '=='. All should work.
Whatever the data type of the column code is, this query should work:
query = cur.execute("SELECT * From TABLE where code = ?", ("000030",))
Try with implicit conversions to integers for the column value and the parameter that you pass:
query = cur.execute("SELECT * From TABLE where code + 0 = ? + 0", ("000030",))
If this does not work, it means that the values of the column code are not like the ones that you posted in your question.
Here's an working example:
import sqlite3
conn = sqlite3.connect(':memory:')
cur = conn.cursor()
cur.execute("""CREATE TABLE test (code TEXT)""")
for i in range(0, 100, 10):
cur.execute("""INSERT INTO test (code) VALUES (?)""", (str(i).zfill(5),))
conn.commit()
cur.execute("""SELECT * FROM test""")
for row in cur:
print(row)
print()
cur.execute("""SELECT code FROM test WHERE code = ?""", ('00030',))
for row in cur:
print(row)
print()
conn.close()
Output
('00000',)
('00010',)
('00020',)
('00030',)
('00040',)
('00050',)
('00060',)
('00070',)
('00080',)
('00090',)
('00030',)
Related
I want to put the result of each column of the result of my request and store them into separate variables, so I can exploit its results.
I precise this is with a SELECt * and not separate requests.
So, If I do for example:
with connection.cursor() as cursor:
# Read a single record
sql = 'SELECT * FROM table'
cursor.execute(sql)
result = cursor.fetchall()
print(result)
I want to do :
a = [results from column1]
b = [results from column2]
The results should be turned into a row and not be left as a column, to make it a dictionary.
It's probably very simple but I'm new with Python / SQL, thank you.
I have a sqlite database named StudentDB which has 3 columns Roll number, Name, Marks. Now I want to fetch only the columns that user selects in the IDE. User can select one column or two or all the three. How can I alter the query accordingly using Python?
I tried:
import sqlite3
sel={"Roll Number":12}
query = 'select * from StudentDB Where({seq})'.format(seq=','.join(['?']*len(sel))),[i for k,i in sel.items()]
con = sqlite3.connect(database)
cur = con.cursor()
cur.execute(query)
all_data = cur.fetchall()
all_data
I am getting:
operation parameter must be str
You should control the text of the query. The where clause shall allways be in the form WHERE colname=value [AND colname2=...] or (better) WHERE colname=? [AND ...] if you want to build a parameterized query.
So you want:
query = 'select * from StudentDB Where ' + ' AND '.join('"{}"=?'.format(col)
for col in sel.keys())
...
cur.execute(query, tuple(sel.values()))
In your code, the query is now a tuple instead of str and that is why the error.
I assume you want to execute a query like below -
select * from StudentDB Where "Roll number"=?
Then you can change the sql query like this (assuming you want and and not or) -
query = "select * from StudentDB Where {seq}".format(seq=" and ".join('"{}"=?'.format(k) for k in sel.keys()))
and execute the query like -
cur.execute(query, tuple(sel.values()))
Please make sure in your code the provided database is defined and contains the database name and studentDB is indeed the table name and not database name.
This is my R piece of code but i want to do the same thing in python, as i am new in it having problems to write the correct code can anybody guide me how to write this is python. I have already made connections of database and also tried simple queries but here i am struggling
sql_command <- "SELECT COUNT(DISTINCT Id) FROM \"Bowlers\";"
total<-as.numeric(dbGetQuery(con, sql_command))
data<-setNames(data.frame(matrix(ncol=8,
nrow=total)),c("Name","Wkts","Ave","Econ","SR","WicketTaker","totalovers",
"Matches"))
for (i in 1:total){
sql_command <- paste("SELECT * FROM \"Bowlers\" where Id = ", i ,";",
sep="")
p<-dbGetQuery(con, sql_command)
p[is.na(p)] <- 0
data$Name[i] = p$bowler[1]
}
after this which works fine how should i proceed to write the loop code:
with engine.connect() as con:
rs=con.execute('SELECT COUNT(DISTINCT id) FROM "Bowlers"')
for row in rs:
print (row)
Use the format method for strings in python to achieve it.
I am using postgresql, but your connection should be similar. Something like:
connect to test database:
import psycopg2
con = psycopg2.connect("dbname='test' user='your_user' host='your_host' password='your_password'")
cur = con.cursor() # cursor method may differ for your connection
loop over your id's:
for i in range(1,total+1):
sql_command = 'SELECT * FROM "Bowlers" WHERE id = {}'.format(i)
cur.execute(sql_command) # execute and fetchall method may differ
rows = cur.fetchall() # check for your connection
print ("output first row for id = {}".format(i))
print (rows[0]) # sanity check, printing first row for ids
print('\n') # rows is a list of tuples
# you can convert them into numpy arrays
I'm using pyodbc to connect to a Teradata database and it seems that something is now working properly:
This:
conn = connect(params)
cur = conn.cursor()
if len(argv) > 1:
query = ''.join(open(argv[1]).readlines())
else:
query = "SELECT count(*) FROM my_table"
cur.execute(query)
print "...done"
print cur.fetchall()
returns what seems to be an overflow, a number like 140630114173190, but in fact there are only 260 entries in the table (which I do get by querying directly on the sql assistant from teradata)
However, when doing a select * the result seems to be correct.
Any idea of what could be going on?
Running on:
Linux eron-redhat-100338 2.6.32-131.0.15.el6.x86_64
Thanks
EDIT: I don't think this is a fetchall() issue. That's only gong to change whether I get a list, or a tuple or whatever but the number won't change.
Interestingly, I discovered that changing to
query = "SELECT CAST(count(*)) AS DECIMAL(10,2) FROM my_table"
does get the right number, only in as float number. Something is going on with the integers.
While fetchall() returns recordset, and you need 1st column of 1st record you should use something like:
print('# of rows: [%s]' % (c.fetchall()[0][0]))
or:
for row in c.fetchall():
print('# of rows: [%s]' % (row[0]))
I have a small database which is legacy from an almost defunct project. This database has a "Patients" table with individual personal data and an unique "Id" field, and an "Exams" table with some fields for each exam, one of these fields being "Patient_Id".
What I want is, for a given patient (row from "Pacientes" table) the exams (rows) from "Exames" table whose "Patient_Id" matches that of the given patient.
I am very beginner with SQL, so if the question is very naive, I apologize.
My working code is the following, but I am using a for loop while I would much rather have a SQL query (which is the very point of using databases, I think...):
#!/usr/bin/env python
# coding: utf-8
import os, sqlite3
conn = sqlite3.connect('BDdata.db3')
conn.row_factory = sqlite3.Row
c = conn.cursor()
c.execute('SELECT * FROM Exames')
exams = c.fetchall()
c.execute('SELECT * FROM Pacientes')
for row in c:
Nome = row['nome']
ID = row['Id']
for exam in exams: # I would like to replace this loop
if exam['Id_Paciente'] == ID: # with a SQL query meaning
print exam['File']
============================
An answer to a similar question seems to be what I want, but I have no idea how to do this in Python with sqlite3 module, much less what in this expression is essential and what is incidental, or what is the syntax structure:
Selecting rows from a table by One a field from other table
SELECT i.prof_image
FROM profile_images i
WHERE cat_id = (select max(cat_id) from images_cat)
I think the following should do what you want:
...
c = conn.cursor()
c.execute('SELECT * FROM Pacientes')
for row in c.fetchall():
Nome = row['nome']
ID = row['Id']
c.execute('SELECT File FROM Exames WHERE Id_Paciente=?', [ID])
for exam in c:
print exam['File']