python更新中的SQLite3，其中有多个可能的匹配项

Question

Perhaps you can help me. I am selecting the oldest # rows in a database, then want to update the date column for each item I selected.

from datetime import datetime
import sqlite3

conn = sqlite3.connect('testing.db')
cursor = conn.cursor()
# Create the table
cursor.execute('CREATE TABLE IF NOT EXISTS players (player_tag TEXT, update_date TEXT, UNIQUE(player_tag));')
max_player_tags = 2
# Insert some data with old dates
arr = [['tag1','20200123T05:06:07'], ['tag2','20200123T05:06:07'], ['tag3','20200123T05:06:07'], ['tag4', datetime.now().isoformat()]]
cursor.executemany('INSERT OR IGNORE INTO PLAYERS values (?, ?)', arr)
conn.commit()
#Select the oldest 2 items
old_tags = [i[0] for i in cursor.execute('SELECT player_tag FROM players ORDER BY update_date DESC LIMIT 2')]
print(old_tags)
#Now update the dates to now
cursor.execute('UPDATE players SET update_date = datetime("now") WHERE player_tag in %s' % old_tags)
print([i for i in 'SELECT * FROM players'])
cursor.close()
conn.close()

The error I get is

    cursor.execute('UPDATE players SET update_date = datetime("now") WHERE player_tag in %s' % old_tags)
sqlite3.OperationalError: no such table: 'tag1', 'tag2'
['tag1', 'tag2']

I have also tried:

cursor.executemany('INSERT OR IGNORE INTO PLAYERS values (?, ?) ON DUPLICATE KEY UPDATE', upd_arr)

Any ideas?

Answer 1

I would just use a single query here:

sql = """UPDATE players
         SET update_date = datetime("now")
         WHERE player_tag IN (SELECT player_tag FROM players
                              ORDER BY update_date DESC LIMIT 2)"""
cursor.execute(sql)