python sqlite循环考虑数据库中的所有表格

Question

我在test.db文件中有700个表格，并且想知道如何循环所有这些表格并返回表格名称，如果columnA值为-？

connection.execute('SELECT * FROM "all_tables" WHERE "columnA" = "-"') 

如何在all_tables中放置全部700个表格？

Answer 1

你可以查询sqlite_master到你的数据库中获得所有的表名：SELECT name FROM sqlite_master WHERE type = 'table'

sqlite_master可以被看作是包含您数据库（元数据）信息的表格。

快速但极有可能低效的方式（因为它会运行700个查询与700个不同的结果集）通过这些表来获取表名的列表，循环和返回数据，其中columnA = "-"：

for row in connection.execute('SELECT name FROM sqlite_master WHERE type = "table" ORDER BY name').fetchall() 
    for result in connection.execute('SELECT * FROM ' + row[1] + ' WHERE "columnA" = "-"').fetchall() 
    # do something with results 

注：上面的代码没有经过测试，但给你一个关于如何解决这个问题的想法。

Answer 2

SQLite的

得到所有表名：

SELECT name FROM sqlite_master WHERE type='table' ORDER BY name; 

周期

for table in tables: 
    ... 
    connection.execute('SELECT * FROM "table1" WHERE "columnA" = "-"') 

或一个SQL UNION要求

sql = [] 
for table in tables 
    sql.append('(SELECT * FROM "' + table + '" WHERE "columnA" = "-";)') 
' UNION '.join(sql) 

Answer 3

要继续围绕着一个主题：

import sqlite3 
try: 
    conn = sqlite3.connect('/home/rolf/my.db') 
except sqlite3.Error as e: 
    print('Db Not found', str(e)) 
db_list = [] 
mycursor = conn.cursor() 
for db_name in mycursor.execute("SELECT name FROM sqlite_master WHERE type = 'table'"): 
    db_list.append(db_name) 
for x in db_list: 
    print "Searching",x[0] 
    try: 
     mycursor.execute('SELECT * FROM '+x[0]+' WHERE columnA" = "-"') 
     stats = mycursor.fetchall() 
     for stat in stats: 
      print stat, "found in ", x 
    except sqlite3.Error as e: 
     continue 
conn.close()