sqlite3，以日期时间选择

Question

The Problem

I am trying to do a sqlite3 query, in Python, using a datetime in the WHERE section.

The placedDate is datetime object, and my code is below. For some reason, the query returns items placed today, rather than bets placed in the last hour. What could be wrong?

    sql = r"""SELECT count(*) FROM bet WHERE placedDate>?"""
    td = timedelta( minutes=60 )
    dt = datetime.utcnow()-td
    with closing( conn.cursor() ) as cur:
        cur.execute( sql, ( dt, ) )
        print cur.fetchone()[0]

I have also tried

sql = r"""SELECT count(*) FROM bet WHERE placedDate>datetime(?)"""

An example placedDate is

 'placedDate': u'2015-02-06T01:20:37.000Z', 

Table Definition

Using

    meta = conn.execute("PRAGMA table_info('bet')")
    print( 'bet table info:')
    for r in meta:
        print r

I get

(0, u'id', u'INTEGER', 0, None, 1)
(1, u'marketId', u'varchar', 0, None, 0)
(2, u'sizeMatched', u'decimal(10,2)', 0, None, 0)
(3, u'orderType', u'varchar', 0, None, 0)
(4, u'selectionId', u'int', 0, None, 0)
(5, u'price', u'decimal(5,2)', 0, None, 0)
(6, u'persistenceType', u'varchar', 0, None, 0)
(7, u'size', u'decimal(10,2)', 0, None, 0)
(8, u'placedDate', u'datetime', 0, None, 0)
(9, u'averagePriceMatched', u'decimal(10,2)', 0, None, 0)
(10, u'side', u'varchar', 0, None, 0)
(11, u'description', u'varchar', 0, None, 0)

Answer 1

This works for me:

 import sqlite3
 from datetime import datetime, timedelta

 conn = sqlite3.connect(":memory:", detect_types=sqlite3.PARSE_DECLTYPES)


 c = conn.cursor()

 c.execute("""
 CREATE TABLE test (
    foo varchar,
    ts datetime
 );""")

 rowcount = c.execute("SELECT COUNT(*) FROM test").fetchone()[0]
 assert 0 == rowcount, rowcount

 dt = timedelta(minutes=5)

 now = datetime.now()

 then = now

 for i in xrange(100):
     then -= dt
     c.execute("INSERT INTO test VALUES(?, ?)", (str(i), then))

 rowcount = c.execute("SELECT COUNT(*) FROM test").fetchone()[0]
 assert 100 == rowcount, rowcount


 hour_ago = now - timedelta(minutes=60)
 rowcount = c.execute(
     "SELECT COUNT(*) FROM test WHERE ts >= ?",
     (hour_ago,) ).fetchone()[0]
 assert 12 == rowcount, rowcount

If it does for you, I suspect the data being different than your expectation.