sqlalchemy select

If the two databases are a physical machine ~ INSERTINTODB. TBSELECT * FROMDA. TAWHERE... but if the two databases belong to two physical machines ~~ I use sqlalchemy ~ Section 1 fetsesssiona.exe cute ( amp; #39; SELECT * FROMTAWHERE... amp; #39 ;). fetchall () Section 2 #39; #39; #39; dict constructed based on fet #39; #39; #39; Section 3 sessionB. add_all (* mysqlsqlalchemypython If the two d

Tags: mysql connectionORM IntroductionBackground:Writing with the underlying SQL is equivalent to connecting the "http://blog.51cto.com/jacksoner/2113454" through a pymysql cursor, in order to avoid writing SQL statements to death in the code, Is there a way to encapsulate native SQL directly and manipulate it in a familiar way, like an object-oriented one? An ORM is an object mapping relationship program. The equivalent of an ORM helps us to write the form of the class in SQL and then call it t

When learning to use the SQLAlchemy module, step on a pit and share it.Bury The hidden dangerI first created a Student information table with the following statement:> CREATE TABLE student ( -> id INT UNSIGNED AUTO_INCREMENT, -> name VARCHAR(20) NOT NULL, -> age TINYINT, -> PRIMARY KEY (id) -> );Table of 3 fields: self-increment ID (unsigned number, the self-increment ID will not be negative, of course, with unsigned, feel good Professi

This article mainly introduces how to use the SQLAlchemy framework of Python. the SQLAlchemy framework is one of the ORM frameworks used to operate databases in Python. if you need it, refer to the following: the database table is a two‑dimensional table, contains multiple rows and multiple columns. If the content of a table is expressed in the Python data structure, a list can be used to represent multiple

Redis is a key-value storage system it supports storing more value types, including string (string), list (linked list), set (set), Zset (sorted set-ordered collection), and hash (hash type). These data types support Push/pop, Add/remove, and intersection sets and differences and richer operations, and these operations are atomicSome uses of Redis# See informationinfo = R.info ()For key in info:Print "%s:%s"% (key, Info[key])# Check Database sizeprint ' \ndbsize:%s '% r.dbsize ()# See Connection

]:3306/s11", max_overflow=5)engine.execute("INSERT INTO ts_test (a, b) VALUES (‘2‘, ‘v1‘)")engine.execute("INSERT INTO ts_test (a, b) VALUES (%s, %s)",((555,"v1"),(666,"v1"),))engine.execute("INSERT INTO ts_test (a, b) VALUES (%(id)s, %(name)s)",id=999, name="v1")result=engine.execute(‘select * from ts_test‘)result.fetchall() Transactional OperationsNote: View database connection: Show status like ' threads% ';Step Two:Use Schema type/sql Expr

(data) 2.9 Sort data = Session.query (User). Order_by (User.name.desc ()). All () print (data) 　　Third, modify the data The first type of assignment # data = session.query (user). Filter (user.name== ' Marry '). First () data = session.query (user). filter_by (Name= ' Marry '). First () data.name = ' Tom ' session.commit () The second type of update Session.query (User) filter_by (name= ' Tom '). Update ({' name ': ' Hary '}) Session.commit () Rolling

mappings Copy Code code as follows: >>> class User (object): ... def __repr__ (self): ... return '%s (%r,%r) '% (self.__class__.__name__, self.name, Self.email) ... >>> Mapper (User, users_table) # Create Mappings >>> ul = User () >>> Ul.name >>> Print ul User (None, none) >>> Print Ul.name None >>> Establish a session Inquire Copy Code code as follows: >>> session = Create_session () >>> session >>> query = Session.query (User

aliasesThree, multi-table query#Multi-Table QueryPrint(Session.query (User,userdetails). Filter (Userdetails.id==user.id). All ())#Cross Join Query methodPrint(Session.query (User.username,userdetails.lost_login). Join (Userdetails,userdetails.id==user.id). Filter ( userdetails.id==user.id). All ())#INNER Join Query method #There's no difference between the two methods in MySQL .Print(Session.query (Userdetails.lost_login,user.username). Outerjoin (User,user.id==userdetails.id). Filter ( u

This article describes how to install sqlalchemy in python in windows and how to prepare tools before installing sqlalchemy. For more information, see For windows operating systems, install easy_install first. . Install setuptools (easy_install ):A. For a 32-bit windows Operating SystemFor a 32-bit windows operating system, find the corresponding exe and install it. B. For a 64-bit windows Operating SystemI

SQLAlchemy ORM, sqlalchemyormI. Installation Pip3 install pymysqlpip3 install sqlalchemyIi. Use From sqlalchemy import create_engineengine = create_engine ('mysql + pymysql ://root: 123456@127.0.0.1/db1? Charset = utf8') # pass the value cursor = engine.exe cute ("insert into t1 values (% s, % s);", [(1, 'egon '), (1, 'egon'), (1, 'egon')]) # pass the value of cursor = engine.exe cute ('insert into t1 val

Creating the engineEgine=create_engine ('Mysql+pymysql://[email Protected]/db1?charset=utf8')#3 Execute your own written SQL statement#egine.execute (' CREATE table if not ' EXISTS t1 (id int PRIMARY KEY auto_increment,name char ( +));#Cur=egine.execute (' INSERT into T1 values (%s,%s); ', [(1, "Egon1"), (2, "Egon2"), (3, "Egon3")]) #按位置传值#Cur=egine.execute (' INSERT into T1 values (% (ID) s,% (name) s); ', name= ' Egon4 ', id=4) #按关键字传值#4 The newly inserted row's self-increment ID#print (CUR.L

(User.Name, Func.sum (user.id). Label ("User_id_sum")). Group_by (User.Name). All ())#子查询stmt = Session.query (address.user_id, Func.count (' * '). Label ("Address_count")). Group_by (address.user_id). Subquery ( )Print (Session.query (User, Stmt.c.address_count). Outerjoin ((stmt, user.id = stmt.c.user_id)). Order_by (user.id). All ())#existsPrint (Session.query (User). Filter (exists (). WHERE (address.user_id = = user.id)))Print (Session.query (User). Filter (User.addresses.any ()))Limit ret

it an "alias", and then we can pass the argument through the alias: Copy Code code as follows: >>> from Sqlalchemy.orm import aliased >>> User_alias = aliased (user, name= ' user_alias ') >>> for row in Session.query (User_alias, User_alias.name). All (): ... print Row.user_alias SELECT User_alias.id as user_alias_id, User_alias.name as User_alias_name, User_alias.fullname as User_alias_fullname, User_alias.password

Label:Initialize and configureORM(Object relational Mapper) objects relational mappings. Refers to a relationship object that maps the method that faces the object to a database.Flask-sqlalchemy is a Flask extension, able to support a variety of database background, we can not need to care about SQL processing details, operations database, a basic relationship corresponding to a class, and an entity corresponding to the class instance object, by invok

representation of the grouping situation. the 1.3 GROUP by keyword is used with the collection function When the group by keyword is used with a collection function, the aggregate record, maximum value, minimum value, and so on, can be calculated from the grouping function. Example: Group the sex field of an employee table into a query. the sex field takes the same value as a group. Each group is then evaluated using the aggregate function count () function to find out the number of records

concurrency conn = pymysql.connect(host=‘‘, port=, user=‘‘, passwd=‘‘, db=‘‘) cus = conn.curse() (2) Execute SQL "select * from Student;" cus.execute(sql) cus.fetchone() 获取单个 返回值 tuple cus.fetchall() 获取多个 返回值 list（单个元素是tuple） cus.fetchmany(size=n) 获取多个 (3) Closing cursors and connections cus.close() conn.close() Note the use of combined try exception finally Ii. Summary of sqlalchemy operation 1. Creating