def delete_data(self, tag, tb_name):
"""
删除数据库中的符合指定条件的记录
:param tag: 字段
:param value: 值
用法：delete from tb_name where xx=xx
:return:
"""
result = []
tb_path = DATABASE_PATH + "%s/%s" % (get_dbname(), tb_name + '.txt')
with open(tb_path, 'r') as f:
res = f.readlines()
for r in res:
raw = r.strip('\n')
li_raw = raw.replace('\t', ',')
li_lst = li_raw.split(',')
if tag not in li_lst:
result.append(r)
with open(tb_path, 'w') as f:
f.writelines(result)
if len(res) == len(result):
print 'The data is not exist!'
else:
print 'Delete data successfully!'
def current_db(self):
"""
显示当前使用的数据库
:return:
"""
current_db_name = get_dbname()
print 'current database:%s' % current_db_name
def create_table(self, tb_name, date):
"""
创建数据表
:param tb_name:
:return:
"""
# 创建用于存储表中数据的磁盘文件
if self.__check_db():
try:
os.mknod(DATABASE_PATH + "%s/%s" %
(get_dbname(), tb_name + '.txt'))
print "Create table %s successfully!" % tb_name
except Exception as e:
print "The table:%s has been existed!" % tb_name
# 创建一张表就会创建一棵树，树的名字就是表的名字
tb_path = DATABASE_PATH + "%s/%s" % (get_dbname(),
tb_name + '.txt')
self.__write_date(tb_path, date, tb_name)
def __check_db(self):
"""
对数据表操作之前必须选定一个数据库
:return:
"""
if not get_dbname():
print 'Please select a database!'
return False
return True
def insert_date(self, date, tb_name):
"""
插入数据，使用方法：insert into tb_name value (xxx=xxx,xxx=xxx)
:param tb_name: 要插入的表的名字
:param date: 要插入的数据
:return:
"""
tb_path = DATABASE_PATH + "%s/%s" % (get_dbname(), tb_name + '.txt')
self.__write_date(tb_path, date, tb_name)
def show_tables(self):
"""
显示当前操作数据库下的所有表
:return:
"""
if self.__check_db():
tbs_lst = []
tbs = os.listdir(DATABASE_PATH + get_dbname())
for t in tbs:
tbs_lst.append(t.split('.')[0])
ui('tbs', tbs_lst)
def drop_table(self, tb_name):
"""
删除表
:param tb_name: 表名
:return:
"""
if self.__check_db():
try:
os.remove(DATABASE_PATH + get_dbname() + "/%s.txt" % tb_name)
print "The tables %s delete successfully!" % tb_name
except Exception as e:
print e
print "The tables %s is not existed!" % tb_name
def operation():
"""
系统操作入口函数
:return:
"""
while True:
oper = raw_input('%s#> ' % get_dbname())
if oper == 'exit':
change_db("")
print 'Bye~'
sys.exit()
else:
sql_analysis(oper)
def rename_table(self, tb_name, new_name):
"""
更改表名
:param tb_name: 原来的表名
:param new_name: 新表名
:return:
"""
if self.__check_db():
path = DATABASE_PATH + get_dbname() + "/"
try:
os.rename(path + tb_name + '.txt', path + new_name + '.txt')
print "The table %s rename successfully!" % tb_name
except Exception as e:
print e
print "The table %s rename failded!" % tb_name
def select_date(self, tag, tb_name):
"""
数据库查询操作
select * from tb_name 查询该数据表中所有记录
select count(*) from tb_name 查询该表中的总记录数量
:param tag: * or count(*)
:param tb_name: 表名
todo!加where 条件查询，只要加where就会用到索引树
:return:
"""
tb_path = DATABASE_PATH + "%s/%s" % (get_dbname(), tb_name + '.txt')
with open(tb_path, 'r') as f:
res = f.readlines()
if tag == '*':
print '----------------------datas--------------------------'
for r in res:
print r.strip('\n')
print '-----------------------------------------------------'
elif tag == 'count(*)':
print 'count: ', len(res)
def update_data(self, tb_name, value, section):
"""
更新记录操作
用法：update tb_name set xx=xx where id=?
:return:
"""
tb_path = DATABASE_PATH + "%s/%s" % (get_dbname(), tb_name + '.txt')
with open(tb_path, 'r') as f:
res = f.readlines()
tag = value.split('=')[0]
flag = False
update_set = []
for r in res:
raw = r.strip('\n')
li_raw = raw.replace('\t', ',')
li_lst = li_raw.split(',')
if section in li_lst:
flag = True
new = []
for i in li_lst:
if i.startswith(tag):
new.append(value)
else:
new.append(i)
new_str = ','.join(new)
new_raw = new_str.replace(',', '\t') + '\n'
update_set.append(new_raw)
else:
update_set.append(r)
if not flag:
print 'error update,the name is not in this data!'
with open(tb_path, 'w') as f:
f.writelines(update_set)
print 'update data successfully!'