python sqlite3进行循环更新

Question

import sqlite3    
conn = sqlite3.connect('sample.db')    
cursor = conn.cursor()    
data = cursor.execute('''SELECT * From Table''')

for i in data:    
    title = i[0]        
    status = i[1]    
    cursor.execute('''UPDATED Table SET status=? WHERE title=?''', (status, title))

cursor.close()    
conn.commit()

I am trying to update over multiple iterations. However, the script breaks out of the loop as soon as the database makes the first update. How to fix this? Thanks!

Answer 1

Use data = data.fetchall() before your loop. Otherwise you wind up recycling the cursor inside of your loop (resetting its result set) while you're trying to loop over that result set.

Using .fetchall() returns a list of results so that you have them stored locally before you re-use the cursor.

Alternatively, create a separate cursor to use for your update statements if you don't want to cache the results of the first query locally.