Question

import sqlite3

class Database1:
    def __init__(self,**args):
        self.filename = args.get('filename')
        self.table = args.get('table','test')

    def sql_do(self,sql,*params):
        self._db.execute(sql,params)

    def insert(self,row):
        self._db.execute('insert into {}(t1,i1)values(?,?)'.format(self._table),(row['t1'],row['i1']))

    def retrieve(self,key):
        cursor = self._db.execute('select * from {} where i1 = ?'.format(self._table),(key,))
        return dict(cursor.fetchone())
    def update(self,row):
        self._db.execute('update {} set t1 = ? where i1 = ?'.format(self._table),(row['t1'],row['i1']))

    def delete(self,key):
        self._db.execute('delete from {} where i1 = ?'.format(self._table))

    def __iter__(self):
        cs = self._db.execute('select * from {} order by i1'.format(self._table))
        for i in cs:
            yield dict(i)       #no dict

    @property
    def filename(self): return self._filename

    @filename.setter
    def filename(self,fn):
        self._filename = fn
        self._db = sqlite3.connect(fn)
        self._db.row_factory = sqlite3.Row
    @filename.deleter
    def filename(self): self.close()

    @property
    def table(self): return self._table

    @table.setter
    def table(self,T): self._table = T
    @table.deleter
    def table(self): self._table = "test"
    def close(self):
        self._db.close()
        del self._filename

def main():
    db = Database1(filename = "dbfile.db",table = "test")

    db.sql_do('drop table if exists dbfile')
    db.sql_do('create table dbfile(t1 text,i1 int)')

    print('Insert data')
    db.insert(dict(t1 = 'one',i1 = 1))
    db.insert(dict(t1 = 'two',i1 = 2))
    db.insert(dict(t1 = 'three',i1 = 3))
    for disp in db: print(disp)

    print('Retrieve data')
    print(db.retrieve(1),db.retrieve(2),db.retrieve(3))

    print('Updateed data')
    db.update(dict(t1 = 'amir',i1 = 1))
    db.update(dict(t1 = 'reza',i1 = 2))
    for disp in db: print(disp)

    print('deleteed data')
    db.delete(3)
    db.delete(1)
    for disp in db: print(disp)


main()

为什么会出错？

Traceback (most recent call last):
  File "c:\Users\Computer Parsian\Desktop\Untitled-1.py", line 76, in <module>
    main()
  File "c:\Users\Computer Parsian\Desktop\Untitled-1.py", line 57, in main
    db.insert(dict(t1 = 'one',i1 = 1))
  File "c:\Users\Computer Parsian\Desktop\Untitled-1.py", line 12, in insert
    self._db.execute('insert into {}(t1,i1)values(?,?)'.format(self._table),(row['t1'],row['i1']))
sqlite3.OperationalError: no such table: test

Answer 1

您的错误是因为根据

创建表时您已将表命名为 dbfile

db.sql_do('drop table if exists dbfile')
db.sql_do('create table dbfile(t1 text,i1 int)')

您随后尝试将数据插入名为 test 的表中，该表不存在，因为唯一的表是 dbfile 。

此外，您在删除具有的绑定中省略了绑定的参数：-

self._db.execute('delete from {} where i1 = ?'.format(self._table))

我相信以下内容符合您的要求（请参见注释以了解所应用的更改）：-

import sqlite3

class Database1:
    def __init__(self,**args):
        self.filename = args.get('filename')
        self.table = args.get('table','test')

    def sql_do(self,sql,*params):
        self._db.execute(sql,params)

    def insert(self,row):
        self._db.execute('insert into {}(t1,i1)values(?,?)'.format(self._table),(row['t1'],row['i1']))

    def retrieve(self,key):
        cursor = self._db.execute('select * from {} where i1 = ?'.format(self._table),(key,))
        return dict(cursor.fetchone())
    def update(self,row):
        self._db.execute('update {} set t1 = ? where i1 = ?'.format(self._table),(row['t1'],row['i1']))

    def delete(self,key):
        self._db.execute('delete from {} where i1 = ?'.format(self._table),(key,)) #<<<<< Amended

    def __iter__(self):
        cs = self._db.execute('select * from {} order by i1'.format(self._table))
        for i in cs:
            yield dict(i)       #no dict

    @property
    def filename(self): return self._filename

    @filename.setter
    def filename(self,fn):
        self._filename = fn
        self._db = sqlite3.connect(fn)
        self._db.row_factory = sqlite3.Row
    @filename.deleter
    def filename(self): self.close()

    @property
    def table(self): return self._table

    @table.setter
    def table(self,T): self._table = T
    @table.deleter
    def table(self): self._table = "test"
    def close(self):
        self._db.close()
        del self._filename

def main():
    table = "test"
    db = Database1(filename = "dbfile.db",table = table) #<<<<< Optional use the single value previously defined

    db.sql_do('drop table if exists ' + table) #<<<<< Amended
    db.sql_do('create table ' + table + '(t1 text,i1 int)') #<<<<< Amended

    print('Insert data')
    db.insert(dict(t1 = 'one',i1 = 1))
    db.insert(dict(t1 = 'two',i1 = 2))
    db.insert(dict(t1 = 'three',i1 = 3))
    for disp in db: print(disp)

    print('Retrieve data')
    print(db.retrieve(1),db.retrieve(2),db.retrieve(3))

    print('Updateed data')
    db.update(dict(t1 = 'amir',i1 = 1))
    db.update(dict(t1 = 'reza',i1 = 2))
    for disp in db: print(disp)

    print('deleteed data')
    db.delete(3)
    db.delete(1)
    for disp in db: print(disp)

main()

运行此命令将导致：-

Insert data
{'t1': 'one', 'i1': 1}
{'t1': 'two', 'i1': 2}
{'t1': 'three', 'i1': 3}
Retrieve data
{'t1': 'one', 'i1': 1} {'t1': 'two', 'i1': 2} {'t1': 'three', 'i1': 3}
Updateed data
{'t1': 'amir', 'i1': 1}
{'t1': 'reza', 'i1': 2}
{'t1': 'three', 'i1': 3}
deleteed data
{'t1': 'reza', 'i1': 2}

Process finished with exit code 0

sqlite3.OperationalError：没有这样的表？

1 个答案: