Python SQLite3 UPDATE WHERE无法更新

Question

Problem: Call my method, values get executed and should get committed, but don't. Method below, but it does not generate any error... nothing happens but values do get printed:

def updateNameWhereTime(self, time, name): # time is a floating point from time.time(), 
                                           # name is a simple string like 'this'
    print(time, name) # This prints right values.
    self.db.execute("UPDATE Flights SET name=(?) WHERE startTime=(?);", (name, time))
    self.db.commit() # Does not save anything to the .db

I quarantined has little of the database has I could, and it works perfectly fine. ( quarantine here ). I know this code should run. Also, I'm a beginner and this is my very first project.

Anything specific that I should be looking for? Is there something I might not be doing?

EDIT: Full code that generates the data here, has static sample html for test runs: https://github.com/SimonWoodburyForget/Experiments/tree/master/WarThunder

Answer 1

Below is the sample code with time as text for now. It is quick and dirty so you can use it to test. I will work on converting it to time.time().

If the datatype of startType function parameter does not match the database startTime datatype that will also be a problem of course and no match will be found to update.

def updateNameWhereTime(time, name): # time is a floating point from time.time(),                        
    print(time, name) 
    c.execute("UPDATE Flights SET name=? WHERE startTime=?;", (name, time))
    conn.commit() 

def insertRows(table, startTime, name):
    c.execute("INSERT INTO Flights VALUES ('"+startTime+"', '"+name+"')")

def printTableRows(table):
    for row in c.execute("SELECT * FROM "+table):
        print row

import sqlite3
conn = sqlite3.connect('example.db')

c = conn.cursor()

c.execute('''DROP TABLE IF EXISTS Flights''')
c.execute('''CREATE TABLE Flights
             (startTime text, name text)''')

print "Inserting rows into table"
insertRows('Flights','2015-04-11 10:00','Test 1')
insertRows('Flights','2015-04-11 10:05','Test 2')
insertRows('Flights','2015-04-11 10:10','Test 3')
insertRows('Flights','2015-04-11 10:15','Test 4')

print "Original data in table"
printTableRows('Flights')

print "Updating rows in table"
updateNameWhereTime('2015-04-11 10:05','Test 2 Updated')
updateNameWhereTime('2015-04-11 10:10','Test 3 Updated')

print "Updated rows in table"
printTableRows('Flights')

Here is the output generated:

Inserting rows into table
Original data in table
(u'2015-04-11 10:00', u'Test 1')
(u'2015-04-11 10:05', u'Test 2')
(u'2015-04-11 10:10', u'Test 3')
(u'2015-04-11 10:15', u'Test 4')
Updating rows in table
('2015-04-11 10:05', 'Test 2 Updated')
('2015-04-11 10:10', 'Test 3 Updated')
Updated rows in table
(u'2015-04-11 10:00', u'Test 1')
(u'2015-04-11 10:05', u'Test 2 Updated')
(u'2015-04-11 10:10', u'Test 3 Updated')
(u'2015-04-11 10:15', u'Test 4')

Answer 2

If you want to store startTime as a date or timestamp then you want to declare the datatype of the column on creation accordingly.

c.execute("create table Flights (..., startTime date or startTime timestamp, ...)")

Note that internally sqlite will not store the data as date or timestamp. The data will be numeric.

Part of your challenge is to make sure the datatype in the update statement matches the datatype that is used when inserting the data into the table.

If you decide to create the startTime column in this manner then the default adapters may be enough for what you need. Here is the link to the documentation and immediately after the sample code that seems most relevant.

https://docs.python.org/2/library/sqlite3.html#sqlite3.PARSE_COLNAMES

import sqlite3
import datetime

con = sqlite3.connect(":memory:",  detect_types=sqlite3.PARSE_DECLTYPES|sqlite3.PARSE_COLNAMES)
cur = con.cursor()
cur.execute("create table test(d date, ts timestamp)")

today = datetime.date.today()
now = datetime.datetime.now()

cur.execute("insert into test(d, ts) values (?, ?)", (today, now))
cur.execute("select d, ts from test")
row = cur.fetchone()
print today, "=>", row[0], type(row[0])
print now, "=>", row[1], type(row[1])

cur.execute('select current_date as "d [date]", current_timestamp as "ts [timestamp]"')
row = cur.fetchone()
print "current_date", row[0], type(row[0])
print "current_timestamp", row[1], type(row[1])