域名預(yù)訂/競(jìng)價(jià),好“米”不錯(cuò)過(guò)
這篇文章主要介紹了基于postgreSql 常用查詢小結(jié),具有很好的參考價(jià)值,希望對(duì)大家有所幫助。一起跟隨小編過(guò)來(lái)看看吧。
1. 日期格式轉(zhuǎn)化(參考)
1select 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'
注:beg_time, end_time以TEXT形式存儲(chǔ),求時(shí)間差時(shí)轉(zhuǎn)化為時(shí)間戳再相減得到結(jié)果(s)
2. select * from (中間結(jié)果) t
select count(*) from (
select chkid, count(*) from abc_table GROUP BY chkid) t
補(bǔ)充:自己寫(xiě)的postgreSQL查詢語(yǔ)句
我就廢話不多說(shuō)了,大家還是直接看代碼吧~
import psycopg2
class PostgreConn():
'''
數(shù)據(jù)庫(kù)連接類
'''
def __init__(self, database, user, password, host, port):
self.conn = psycopg2.connect(database=database, user=user, password=password, host=host, port=port)
print('數(shù)據(jù)庫(kù)連接成功')
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('數(shù)據(jù)庫(kù)連接關(guān)閉')
def select_sql(table, keys, conditions, isdistinct=0):
'''
生成select的sql語(yǔ)句
@table,查詢記錄的表名
@key,需要查詢的字段
@conditions,插入的數(shù)據(jù),字典
@isdistinct,查詢的數(shù)據(jù)是否不重復(fù)
'''
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):
'''
將字典變成,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: 數(shù)據(jù)庫(kù)fetchall的結(jié)果
:param key_list: 查詢字段的keys
:return:
format SQL Result 格式化數(shù)據(jù)庫(kù)查詢的結(jié)果,轉(zhuǎn)化成包含多個(gè)字典的列表格式,即((1,2),(3,4))->[{"key1":1,"key2":2},{"key1":3,"key2":4}]
返回 @dict 查詢結(jié)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()
文章來(lái)源:腳本之家
來(lái)源地址:https://www.jb51.net/article/204847.htm
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