I am new to Python and am hoping someone can help me figure out how to perform an SQL query on each item in a tuple using Python.
I have a SQL Express server that contains a number of databases for a badge reader system. What I am trying to do is pull the user id's that have scanned into a particular reader, then use those id's to get the actual user names.
Currently, I am able run the query that pulls the user id's and run a query on the other table using just one id. What want to be able to do, and seem to be having an issue figuring out, is running that second query on every user id in the tuple that is created from the first query. Below is the code for the two functions I am currently using.
def get_id():
global cardholder
global cur
cur.execute("SELECT user_id FROM db.table WHERE badgereaderid = 'badgereader1'")
cardholder = []
rows = cur.fetchall()
for row in rows:
if row == None:
break
cardholder.append(row[0])
print(cardholder)
def get_name():
global cardholder
global user
global cur
cur.execute("SELECT FirstName, LastName FROM db.table WHERE user_id= '%s'" % cardholder)
while 1:
row = cur.fetchone()
if row == None:
break
user = row[0] + row[1]
Two possible options
Repeated queries in Python
for user_id in cardholder:
cur.execute("SELECT FirstName, LastName FROM db.table WHERE user_id= '%s'" % user_id)
But why not just pull all the data in the first query?
cur.execute("SELECT a.user_id, b.FirstName, b.LastName FROM db.table1 a left join bd.table2 b on a.user_id = b.user_id WHERE a.badgereaderid = 'badgereader1'")
or, use triple quotes to allow multi-line strings and make the SQL command easier to understand
cur.execute("""SELECT
a.user_id,
b.FirstName,
b.LastName
FROM db.table1 a
left join db.table2 b
on a.user_id = b.user_id
WHERE a.badgereaderid = 'badgereader1'""")
A good practice in Python is to define the data collections outside the function if you intend to use them later on in your code
Try this code:
cardholder_names = []
#pass the cardholder as a param to the function
def get_name(cardholder):
#cur is already defined as a global param, no need to do it twice
cur.execute("SELECT FirstName, LastName FROM db.table WHERE user_id='{0}'".format(cardholder))
return cur.fetchone()
#now use the for loop to iterate over all the cardholders
for holder in cardholders:
cardholder_name = get_name(holder)
cardholder_names.append( {"name" : cardholder_name[0], "surname" : cardholder_name[1]})
Related
python & mysql
I am making a query on MySQL database in python module, as follows :
qry = "select qtext,a1,a2,a3,a4,rightanswer from question where qno = 1 ")
mycursor.execute(qry)
myresult = mycursor.fetchone()
qtext.insert('1', myresult[0])
I access the fields by their index number (i.e myresult[0])
my question is how can I access fields by their field-name instead of their index in the query ?
I have to add the following line before executing the query
mycursor = mydb.cursor(dictionary=True)
this line converts the query result to a dictionary that enabled me to access fields by their names names instead of index as follows
qtext.insert('1', myresult["qtext"])
qanswer1.insert('1',myresult["a1"]) # working
qanswer2.insert('1',myresult["a2"]) # working
qanswer3.insert('1',myresult["a3"]) # working
qanswer4.insert('1',myresult["a4"]) # working
r = int(myresult["rightanswer"])
Here is your answer: How to retrieve SQL result column value using column name in Python?
cursor.execute("SELECT name, category FROM animal")
result_set = cursor.fetchall()
for row in result_set:
print "%s, %s" % (row["name"], row["category"])```
I am currently working on a coursework project for school and it is a database system with a user interface using Tkinter, Python and SQLite3. I have made a form to add, delete, update and search for customers. I am able to display the result from a single field, however, I am struggling to get the message box to display all the fields, which is what I would like it to do. I have attached photos of the form along with the code. Thank you in advance.
def SearchCustomer(self):
customerid = self.CustomerEntry.get();
with sqlite3.connect("LeeOpt.db") as db:
cursor = db.cursor()
search_customer = ('''SELECT * FROM Customer WHERE CustomerID = ?''')
cursor.execute(search_customer, [(customerid)])
results = cursor.fetchall()
if results:
for i in results:
tkinter.messagebox.showinfo("Notification",i[0])
It is because you showed only the first column (i[0]) from result.
Since there should be only one record for a specific customer ID, you should use fetchone() instead of fetchall(), then you can show the whole record as below:
def SearchCustomer(self):
customerid = self.CustomerEntry.get()
with sqlite3.connect("LeeOpt.db") as db:
cursor = db.cursor()
search_customer = "SELECT * FROM Customer WHERE CustomerID = ?"
cursor.execute(search_customer, [customerid])
result = cursor.fetchone() # there should be only one record for specific customer ID
if result:
tkinter.messagebox.showinfo("Notification", "\n".join(str(x) for x in result))
I need to do a SELECT to an SQL Server table and treat the information I get separately.
For example, let's say I have this table named Table1
And I do this SELECT in python:
SELECT name, phone, date FROM Table1
In the print the result would be:
[['Sara Miller',611111111],['Jane Smith',622222222],['Amanda
Laurens',633333333]]
I need to treat each row and each name and phone number separately to send SMS... So, how can I access each one using Python?
For example, to send an SMS to the number 611111111 saying
"Dear Sara Miller, tomorrow (20/05/2020) you have an appointment in
the Clinic"
The SMS part I have covered, using an API, the problem is I can't figure out how to treat received data from SQL Server.
The code I have at the moment is:
conn = pypyodbc.connect("Connection parameters, waorking OK")
cursor = conn.cursor()
cursor.execute('SELECT name, phone, date FROM Table1')
result = cursor.fetchall()
final_result = [list(i) for i in result]
print(final_result)
If I need to clarify something please let me know.
I haven't really worked with pypyodbc so I'm not sure what the format of the data that cursor.fetchall returns so I have listed two approaches which should cover both scenarios.
conn = pypyodbc.connect("Connection parameters, waorking OK")
cursor = conn.cursor()
cursor.execute('SELECT name, phone, date FROM Table1')
for row in cursor.fetchall():
name = row[0]
phone = row[1]
date = row[2]
# do something with these variables
If the result returned is a dict instead of a list then it becomes:
for row in cursor.fetchall():
name = row['name']
phone = row['phone']
date = row['date']
# do something with these variables
Or as #DanGuzman mentions we can also do:
for row in cursor.fetchall():
name = row.name
phone = row.phone
date = row.date
# do something with these variables
I have a large postgresql DB of users that I connect with using psycopg2. I need to retrieve (SELECT) the information of a specific large subset of users (>200). I am provided with a list of ids and I need to return the age of each of those users. I put down a working solution:
conn = psycopg2.connect("dbname= bla bla bla")
cur = conn.cursor()
for user_id in interesting_users:
qr = "SELECT age FROM users WHERE country_code = {0} AND user_id = {1}".format(1, user_id)
cur.execute(qr)
fetched_row = cur.fetchall()
#parse results
This solution works fine, however it is not ideal when the length of interesting_users is large. I am looking for a more efficient approach than executing multiple queries. One solution would be to create a single query by appending all the user ids:
for user_id in interesting_users:
query += "OR user_id {0}".format(user_id)
But I was hoping for a more elegant solution.
I found that psycopg2 provides the executemany() method. So, I tried to apply to my problem. However, I can't manage to make it work. This:
cur.executemany("SELECT age FROM users WHERE country_code = %s AND user_id = %s",[(1, user_id) for user_id in interesting_users])
r = cur.fetchall()
returns:
r = cur.fetchall()
psycopg2.ProgrammingError: no results to fetch
So, can executemany() be used for a SELECT statement? If yes, what's wrong with my code? If no, how can I perform multiple SELECT queries at once?
Note: ids in interesting_users have no order so I can't use something like WHERE id < ...
SOLUTION:
query = "SELECT age FROM users WHERE country_code = {0} AND user_id IN ({1});".format(1, ",".join(map(str, interesting_users)))
cur.execute(query)
fetched_rows = cur.fetchall()
executemany works only with INSERT, not SELECT. Use IN:
cur.executemany("SELECT age FROM users WHERE country_code = %s AND user_id IN ({})".format(','.join(['%s'] * len(interesting_users)),
[1] + interesting_users)
r = cur.fetchall()
I am trying to get the rowid of a username in sqlite3, i have got the basics of it but when ever i run it i get somthing like 'sqlite3.Cursor object at 0x03885660' and it changes every time i run it with the same username. I know it is because i print rowid but i cant find an alternative way.
here is my code:
def sign_in():
username = input("What is your username?")
password = input("What is your password?")
c.execute("SELECT username FROM stuffToPlot")
names = {name[0] for name in c.fetchall()}
if username in names:
rowid = c.execute("SELECT rowid, * FROM stuffToPlot WHERE username = (username)")
print(rowid)
You got to the point where your cursor executes that query, but then you need to tell it what to return from it. Return the first match with that query? return every record? Fetch the data depending on what you need. You can use fetchone(), fetchall() or many other ways to get it.
if username in names:
c.execute("SELECT rowid, * FROM stuffToPlot WHERE username = (username)")
rowid = c.fetchone()
print(rowid)