#_*_coding:utf-8_*_#第一部分:sql解析import osdef sql_parse(sql): ‘‘‘ sql_parse--->insert_parse,delete_parse,update_parse,select_parse sql解析总控 :param sql:用户输入的字符串 :return: 返回字典格式sql解析结果 ‘‘‘‘‘ parse_func={ ‘insert‘:insert_parse, ‘delete‘:delete_parse, ‘update‘:update_parse, ‘select‘:select_parse, } sql_l=sql.split(‘ ‘) func=sql_l[0] res=‘‘ if func in parse_func: res=parse_func[func](sql_l) return res
def insert_parse(sql_l): # insert into db.t1 values 鲁海宝,35,13910015353,测试,2005-06-27 ‘‘‘ sql解析分支:insert :param sql_l: sql按照空格分割的列表 :return: 返回字典格式的sql解析结果 ‘‘‘‘‘ sql_dic={ ‘func‘:insert, #函数名 ‘insert‘:[], #insert选项,留出扩展 ‘into‘:[], #表名 ‘values‘:[], #值 } return handle_parse(sql_l,sql_dic)
def delete_parse(sql_l): # delete from db.t1 where id=1 ‘‘‘ sql解析分支:delete :param sql_l: sql按照空格分割的列表 :return: 返回字典格式的sql解析结果 ‘‘‘‘‘ sql_dic={ ‘func‘:delete, ‘delete‘:[], #delete选项,留出扩展 ‘from‘:[], #表名 ‘where‘:[], #filter条件 } return handle_parse(sql_l,sql_dic)
def update_parse(sql_l): # update db.t1 set id=2 where name=‘alex‘ ‘‘‘ sql解析分支:update :param sql_l: sql按照空格分割的列表 :return: 返回字典格式的sql解析结果 ‘‘‘‘‘ sql_dic={ ‘func‘:update, ‘update‘:[], #update选项,留出扩展 ‘set‘:[], #修改的值 ‘where‘:[], #filter条件 } return handle_parse(sql_l,sql_dic)
def select_parse(sql_l): # select * from db1.emp where not id= 1 and name = ‘alex‘ or name= ‘sb‘ limit 3 ‘‘‘ sql解析分支:select :param sql_l: sql按照空格分割的列表 :return: 返回字典格式的sql解析结果 ‘‘‘‘‘ sql_dic={ ‘func‘:select, ‘select‘:[], #查询字段 ‘from‘:[], #表 ‘where‘:[], #filter条件 ‘limit‘:[], #limit条件 } return handle_parse(sql_l,sql_dic)
def handle_parse(sql_l,sql_dic): ‘‘‘ 填充sql_dic :param sql_l: sql按照空格分割的列表 :param sql_dic: 待填充的字典 :return: 返回字典格式的sql解析结果 ‘‘‘‘‘ tag=False for item in sql_l: if tag and item in sql_dic: tag=False if not tag and item in sql_dic: tag=True key=item continue if tag: sql_dic[key].append(item) # print(‘before \033[33;1m%s\033[0m‘ %sql_dic) if sql_dic.get(‘where‘): sql_dic[‘where‘]=where_parse(sql_dic.get(‘where‘))
# print(‘after \033[33;1m%s\033[0m‘ %sql_dic) return sql_dic
def where_parse(where_l): ‘‘‘ 对用户输入的where子句后的条件格式化,每个子条件都改成列表形式 :param where_l: 用户输入where后对应的过滤条件列表 :return: ‘‘‘‘‘ res=[] key=[‘and‘,‘or‘,‘not‘] char=‘‘ for i in where_l: if len(i) == 0:continue if i in key: if len(char) != 0: char=three_parse(char) #将每一个小的过滤条件如,name>=1转换成[‘name‘,‘>=‘,‘1‘] res.append(char) res.append(i) char=‘‘ else: char+=i else: char=three_parse(char) res.append(char) return res
def three_parse(exp_str): ‘‘‘ 将每一个小的过滤条件如,name>=1转换成[‘name‘,‘>=‘,‘1‘] :param exp_str:条件表达式的字符串形式,例如‘name>=1‘ :return: ‘‘‘‘‘ # print(‘three_opt before is \033[34;1m%s\033[0m‘ %exp_str) key=[‘>‘,‘=‘,‘<‘] res=[] char=‘‘ opt=‘‘ tag=False for i in exp_str: if i in key: tag=True if len(char) !=0: res.append(char) char=‘‘ opt+=i if not tag: char+=i if tag and i not in key: tag=False res.append(opt) opt=‘‘ char+=i else: res.append(char) # print(‘res is %s ‘ %res) #新增like功能 if len(res) == 1:#[‘namelike_ale5‘] res=res[0].split(‘like‘) res.insert(1,‘like‘) return res
#第二部分:sql执行def sql_action(sql_dic): ‘‘‘ 执行sql的统一接口,内部执行细节对用户完全透明 :param sql: :return: ‘‘‘‘‘ return sql_dic.get(‘func‘)(sql_dic)
def insert(sql_dic): print(‘insert %s‘ %sql_dic) db,table=sql_dic.get(‘into‘)[0].split(‘.‘) with open(‘%s/%s‘ %(db,table),‘ab+‘) as fh: offs = -100 while True: fh.seek(offs,2) lines = fh.readlines() if len(lines)>1: last = lines[-1] break offs *= 2 last=last.decode(encoding=‘utf-8‘) last_id=int(last.split(‘,‘)[0]) new_id=last_id+1 #insert into db1.emp values 张国辉,30,18500841678,运维,2007-8-1 record=sql_dic.get(‘values‘)[0].split(‘,‘) record.insert(0,str(new_id)) #[‘26‘, ‘alex‘, ‘18‘, ‘13120378203‘, ‘运维‘, ‘2013-3-1\n‘] record_str=‘,‘.join(record)+‘\n‘ fh.write(bytes(record_str,encoding=‘utf-8‘)) fh.flush() return [[‘insert successful‘]]
def delete(sql_dic): db,table=sql_dic.get(‘from‘)[0].split(‘.‘) bak_file=table+‘_bak‘ with open("%s/%s" %(db,table),‘r‘,encoding=‘utf-8‘) as r_file,\ open(‘%s/%s‘ %(db,bak_file),‘w‘,encoding=‘utf-8‘) as w_file: del_count=0 for line in r_file: title="id,name,age,phone,dept,enroll_date" dic=dict(zip(title.split(‘,‘),line.split(‘,‘))) filter_res=logic_action(dic,sql_dic.get(‘where‘)) if not filter_res: w_file.write(line) else: del_count+=1 w_file.flush() os.remove("%s/%s" % (db, table)) os.rename("%s/%s" %(db,bak_file),"%s/%s" %(db,table)) return [[del_count],[‘delete successful‘]]
def update(sql_dic): #update db1.emp set id=‘sb‘ where name like alex db,table=sql_dic.get(‘update‘)[0].split(‘.‘) set=sql_dic.get(‘set‘)[0].split(‘,‘) set_l=[] for i in set: set_l.append(i.split(‘=‘)) bak_file=table+‘_bak‘ with open("%s/%s" %(db,table),‘r‘,encoding=‘utf-8‘) as r_file,\ open(‘%s/%s‘ %(db,bak_file),‘w‘,encoding=‘utf-8‘) as w_file: update_count=0 for line in r_file: title="id,name,age,phone,dept,enroll_date" dic=dict(zip(title.split(‘,‘),line.split(‘,‘))) filter_res=logic_action(dic,sql_dic.get(‘where‘)) if filter_res: for i in set_l: k=i[0] v=i[-1].strip("‘") print(‘k v %s %s‘ %(k,v)) dic[k]=v print(‘change dic is %s ‘ %dic) line=[] for i in title.split(‘,‘): line.append(dic[i]) update_count+=1 line=‘,‘.join(line) w_file.write(line)
w_file.flush() os.remove("%s/%s" % (db, table)) os.rename("%s/%s" %(db,bak_file),"%s/%s" %(db,table)) return [[update_count],[‘update successful‘]]
def select(sql_dic): db,table=sql_dic.get(‘from‘)[0].split(‘.‘) fh=open("%s/%s" %(db,table),‘r‘,encoding=‘utf-8‘)
filter_res=where_action(fh,sql_dic.get(‘where‘)) # print(‘filter_res is ====>‘,filter_res) fh.close()
limit_res=limit_action(filter_res,sql_dic.get(‘limit‘)) # print(‘limit_res is ====>‘,limit_res)
search_res=search_action(limit_res,sql_dic.get(‘select‘)) # print(‘select_res is ====>‘,search_res)
return search_res
def where_action(fh,where_l): res=[] logic_l=[‘and‘,‘or‘,‘not‘] title="id,name,age,phone,dept,enroll_date" if len(where_l) !=0: for line in fh: dic=dict(zip(title.split(‘,‘),line.split(‘,‘))) logic_res=logic_action(dic,where_l) if logic_res: res.append(line.split(‘,‘)) else: res=fh.readlines() return res
def logic_action(dic,where_l): res=[] # print(‘==\033[45;1m%s\033[0m==\033[48;1m%s\033[0m‘ %(dic,where_l)) for exp in where_l: if type(exp) is list: exp_k,opt,exp_v=exp if exp[1] == ‘=‘: opt=‘%s=‘ %exp[1] if dic[exp_k].isdigit(): dic_v=int(dic[exp_k]) exp_v=int(exp_v) else: dic_v="‘%s‘" %dic[exp_k] if opt != ‘like‘: exp=str(eval("%s%s%s" %(dic_v,opt,exp_v))) else: if exp_v in dic_v: exp=‘True‘ else: exp=‘False‘ res.append(exp) res=eval(‘ ‘.join(res)) # print(‘==\033[45;1m%s\033[0m‘ %(res)) return res
def limit_action(filter_res,limit_l): res=[] if len(limit_l) !=0: index=int(limit_l[0]) res=filter_res[0:index] else: res=filter_res
return res
def search_action(limit_res,select_l): res=[] fileds_l=[] title="id,name,age,phone,dept,enroll_date" if select_l[0] == ‘*‘: res=limit_res fileds_l=title.split(‘,‘) else:
for record in limit_res: dic=dict(zip(title.split(‘,‘),record)) # print("dic is %s " %dic) fileds_l=select_l[0].split(‘,‘) r_l=[] for i in fileds_l: r_l.append(dic[i].strip()) res.append(r_l)
return [fileds_l,res]
if __name__ == ‘__main__‘: while True: sql=input("sql> ").strip() if sql == ‘exit‘:break if len(sql) == 0:continue
sql_dic=sql_parse(sql)
if len(sql_dic) == 0:continue #输入命令非法 res=sql_action(sql_dic)
for i in res[-1]: print(i)
时间： 2024-07-30 19:43:36