I'm making Car parking system, and I have some difficulities with SQL database.
I'm selecting data from SQL database, but I need to get the time correctly that I could use it for further calculations. So for example I need to get the time that was inserted to database as VARCHAR, maybe the bad thing is that I needed to use other method as TIME, but that's not the case. The thing I need is to use this line Started_Parking = row [3]. This should get the time from database and after that, I should be able to see the time difference from the start when car was registered and current time. By doing that I should be able to calculate the sum which the "User" should pay for parking.
So by short I just need to somehow get the time from database and use it for calculations. Here's my code, I also get errors when compiling :
Error while fetching data from PostgreSQL unsupported operand type(s) for -: 'datetime.datetime' and 'str'
try:
connection = psycopg2.connect(user="postgres",
password="Dziugas420",
host="127.0.0.1",
port="5432",
database="postgres")
cursor = connection.cursor()
postgreSQL_select_Query = "select * from vartotojai WHERE carnum=('%s')" % car_numb
cursor.execute(postgreSQL_select_Query) # PALEIST KOMANDA
vartotoju_data = cursor.fetchall() # READ DATA
print(" CAR DETAILS: ")
for row in vartotoju_data:
print("Current ID: ", row[0])
print("Car Number: ", row[1])
print("Parked on: ", row[3], "\n")
Pay_Time = datetime.datetime.now()
Started_Parking = row [3]
Prastovetas_Laikas = Pay_Time - Started_Parking
print(Prastovetas_Laikas)
# NOW LET'S CHECK IF THE TIME DIFFERENCE IS WORKING, LET'S SEE THE DIFFERENCE AFTER 20SECS.
time.sleep(20)
Pay_Time2 = datetime.datetime.now()
Prastovetas_Laikas2 = Pay_Time2 - Started_Parking
print(Prastovetas_Laikas2)`
**EDIT
Here's the code I use to import this time into database:
Car_Reg_Time = datetime.datetime.now().strftime("%Y-%m-%d %H:%M")
postgres_insert_query = """ INSERT INTO vartotojai (CARNUM, TIME, LAIKAS) VALUES (%s,%s, %s)"""
record_to_insert = (car_numb, Reg_Tikslus_Laikas, Car_Reg_Time)
And here's the table of my database:
! laikas in database is when car was registered, the time in database is the time when the injection was made.
