基于postgreSql 常用查询小结

select beg_time, end_time, extract(epoch from to_timestamp(end_time,’yyyy-mm-dd-HH24-MI-SS-US’))-extract(epoch from to_timestamp(beg_time,’yyyy-mm-dd-HH24-MI-SS-US’)) from cdb_all_iu_data where beg_time > ‘2017-09-21’

select count(*) from (
select chkid, count(*) from abc_table GROUP BY chkid) t

import psycopg2
class PostgreConn():
”’
数据库连接类
”’
def __init__(self, database, user, password, host, port):
self.conn = psycopg2.connect(database=database, user=user, password=password, host=host, port=port)
print(‘数据库连接成功’)
self.cur = self.conn.cursor()
self.rows = None

def cur(self):
return self.cur()

def execute(self, sql, fetchone=0):
self.cur.execute(sql)
if fetchone:
self.rows = self.cur.fetchone()
else:
self.rows = self.cur.fetchall()
return self.rows

def close(self):
self.cur.close()
self.conn.close()
print(‘数据库连接关闭’)

def select_sql(table, keys, conditions, isdistinct=0):
”’
生成select的sql语句
@table，查询记录的表名
@key，需要查询的字段
@conditions,插入的数据，字典
@isdistinct,查询的数据是否不重复
”’
if isdistinct:
sql = ‘SELECT distinct %s ‘ % “,”.join(keys)
else:
sql = ‘SELECT %s ‘ % “,”.join(keys)
sql += ‘ from %s ‘ % table
if conditions:
sql += ‘ WHERE %s ‘ % dict_str_and(conditions)
return sql

def dict_str_and(dictin):
”’
将字典变成，key=’value’ and key=’value’的形式
”’
tmplist = []
for k, v in dictin.items():
tmp = “%s=’%s'” % (str(k), str(v))
tmplist.append(‘ ‘ + tmp + ‘ ‘)
return ‘ and ‘.join(tmplist)

def fSqlResult(r,key_list):
”’
:param r: 数据库fetchall的结果
:param key_list: 查询字段的keys
:return:
format SQL Result 格式化数据库查询的结果，转化成包含多个字典的列表格式，即((1,2),(3,4))->[{“key1″:1,”key2”:2},{“key1″:3,”key2″:4}]
返回 @dict 查询结果
”’
mlist=[]
l=len(key_list)
if r:
for item in r:
tmp={}
for i in range(l):
tmp[key_list[i]]=str(item[i])
mlist.append(tmp)
return mlist

conn = PostgreConn(‘settle’, ‘admin’, ‘settle8’, ‘123.57.285.89’, ‘5432’)
key_list = [‘user_id’]
sql = select_sql(‘st_user’, key_list, {‘phone’: ‘138****’})
print(sql)
r = conn.execute(sql)
re = fSqlResult(r, key_list)
print(re)
conn.close()