import sqlite3
# ***************************************************
# *
# * Description: Python操作SQLite3数据库辅助类(查询构造器)
# * Author: wangye
# *
# ***************************************************
def _wrap_value(value):
return repr(value)
def _wrap_values(values):
return list(map(_wrap_value, values))
def _wrap_fields(fields):
for key,value in fields.items():
fields[key] = _wrap_value(value)
return fields
def _concat_keys(keys):
return "[" + "],[".join(keys) + "]"
def _concat_values(values):
return ",".join(values)
def _concat_fields(fields, operator = (None, ",")):
if operator:
unit_operator, group_operator = operator
# fields = _wrap_fields(fields)
compiled = []
for key,value in fields.items():
compiled.append("[" + key + "]")
if unit_operator:
compiled.append(unit_operator)
compiled.append(value)
compiled.append(group_operator)
compiled.pop() # pop last group_operator
return " ".join(compiled)
class DataCondition(object):
"""
本类用于操作SQL构造器辅助类的条件语句部分
例如:
DataCondition(("=", "AND"), id = 26)
DataCondition(("=", "AND"), True, id = 26)
"""
def __init__(self, operator = ("=", "AND"), ingroup = True, **kwargs):
"""
构造方法
参数:
operator 操作符，分为(表达式操作符, 条件运算符)
ingroup 是否分组，如果分组，将以括号包含
kwargs 键值元组，包含数据库表的列名以及值
注意这里的等于号不等于实际生成SQL语句符号
实际符号是由operator[0]控制的
例如:
DataCondition(("=", "AND"), id = 26)
(id=26)
DataCondition((">", "OR"), id = 26, age = 35)
(id>26 OR age>35)
DataCondition(("LIKE", "OR"), False, name = "John", company = "Google")
name LIKE 'John' OR company LIKE "Google"
"""
self.ingroup = ingroup
self.fields = kwargs
self.operator = operator
def __unicode__(self):
self.fields = _wrap_fields(self.fields)
result = _concat_fields(self.fields, self.operator)
if self.ingroup:
return "(" + result + ")"
return result
def __str__(self):
return self.__unicode__()
def toString(self):
return self.__unicode__()
class DataHelper(object):
"""
SQLite3 数据查询辅助类
"""
def __init__(self, filename):
"""
构造方法
参数: filename 为SQLite3 数据库文件名
"""
self.file_name = filename
def open(self):
"""
打开数据库并设置游标
"""
self.connection = sqlite3.connect(self.file_name)
self.cursor = self.connection.cursor()
return self
def close(self):
"""
关闭数据库，注意若不显式调用此方法，
在类被回收时也会尝试调用
"""
if hasattr(self, "connection") and self.connection:
self.connection.close()
def __del__(self):
"""
析构方法，做一些清理工作
"""
self.close()
def commit(self):
"""
提交事务
SELECT语句不需要此操作，默认的execute方法的
commit_at_once设为True会隐式调用此方法，
否则就需要显示调用本方法。
"""
self.connection.commit()
def execute(self, sql = None, commit_at_once = True):
"""
执行SQL语句
参数:
sql 要执行的SQL语句，若为None，则调用构造器生成的SQL语句。
commit_at_once 是否立即提交事务，如果不立即提交，
对于非查询操作，则需要调用commit显式提交。
"""
if not sql:
sql = self.sql
self.cursor.execute(sql)
if commit_at_once:
self.commit()
def fetchone(self, sql = None):
"""
取一条记录
"""
self.execute(sql, False)
return self.cursor.fetchone()
def fetchall(self, sql = None):
"""
取所有记录
"""
self.execute(sql, False)
return self.cursor.fetchall()
def __concat_keys(self, keys):
return _concat_keys(keys)
def __concat_values(self, values):
return _concat_values(values)
def table(self, *args):
"""
设置查询的表，多个表名用逗号分隔
"""
self.tables = args
self.tables_snippet = self.__concat_keys(self.tables)
return self
def __wrap_value(self, value):
return _wrap_value(value)
def __wrap_values(self, values):
return _wrap_values(values)
def __wrap_fields(self, fields):
return _wrap_fields(fields)
def __where(self):
# self.condition_snippet
if hasattr(self, "condition_snippet"):
self.where_snippet = " WHERE " + self.condition_snippet
def __select(self):
template = "SELECT %(keys)s FROM %(tables)s"
body_snippet_fields = {
"tables" : self.tables_snippet,
"keys" : self.__concat_keys(self.body_keys),
}
self.sql = template % body_snippet_fields
def __insert(self):
template = "INSERT INTO %(tables)s (%(keys)s) VALUES (%(values)s)"
body_snippet_fields = {
"tables" : self.tables_snippet,
"keys" : self.__concat_keys(list(self.body_fields.keys())),
"values" : self.__concat_values(list(self.body_fields.values()))
}
self.sql = template % body_snippet_fields
def __update(self):
template = "UPDATE %(tables)s SET %(fields)s"
body_snippet_fields = {
"tables" : self.tables_snippet,
"fields" : _concat_fields(self.body_fields, ("=",","))
}
self.sql = template % body_snippet_fields
def __delete(self):
template = "DELETE FROM %(tables)s"
body_snippet_fields = {
"tables" : self.tables_snippet
}
self.sql = template % body_snippet_fields
def __build(self):
{
"SELECT": self.__select,
"INSERT": self.__insert,
"UPDATE": self.__update,
"DELETE": self.__delete
}[self.current_token]()
def __unicode__(self):
return self.sql
def __str__(self):
return self.__unicode__()
def select(self, *args):
self.current_token = "SELECT"
self.body_keys = args
self.__build()
return self
def insert(self, **kwargs):
self.current_token = "INSERT"
self.body_fields = self.__wrap_fields(kwargs)
self.__build()
return self
def update(self, **kwargs):
self.current_token = "UPDATE"
self.body_fields = self.__wrap_fields(kwargs)
self.__build()
return self
def delete(self, *conditions):
self.current_token = "DELETE"
self.__build()
#if *conditions:
self.where(*conditions)
return self
def where(self, *conditions):
conditions = list(map(str, conditions))
self.condition_snippet = " AND ".join(conditions)
self.__where()
if hasattr(self, "where_snippet"):
self.sql += self.where_snippet
return self
下面举几个例子供大家参考吧：
复制代码 代码如下:
db = DataHelper("/home/wangye/sample.db3")
db.open() # 打开数据库
db.execute("""
CREATE TABLE [staffs] (
[staff_id] INTEGER PRIMARY KEY AUTOINCREMENT,
[staff_name] TEXT NOT NULL,
[staff_cardnum] TEXT NOT NULL,
[staff_reserved] INTEGER NOT NULL
)
""") # 直接执行SQL语句，注意这里commit_at_once默认为True
db.table("staffs").insert(staff_name="John", staff_cardnum="1001", staff_reserved=0)
# 插入一条记录
rs = db.table("staffs").select("staff_id", "staff_name").fetchall()
# 直接取出所有staff_id和staff_name
rs = db.table("staffs").select("staff_name").where(DataCondition(("=", "AND"), id = 1)).fetchone()
# 取一条staff_id为1的staff_name
rs = db.table("staffs").select("staff_name").where(DataCondition(("# 取一条id小于100并且staff_reserved为1的staff_name记录
db.close() # 关闭数据库
目前还没有让其支持星号(*)操作符，另外在多表同名列操作方面处理得也不是很好，这个只用于日常简单的脚本操作，最好不要用于生产环境，因为可能有未知问题。
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