sqlalchemy

Continue on a sqlalchemy learning journey.Creation of many-to-many tablesTable host and table Hostuser are associated by table Hosttohostuserfromsqlalchemyimportcreate_enginefromsqlalchemy.ext.declarativeimport Declarative_basefromsqlalchemyimportcolumn,integer,string,foreignkey, UniqueConstraint,Index,Tablefromsqlalchemy.ormimportsessionmaker, Relationshipengine=create_engine ("Mysql+pymysql://yli:[emailprotected]:3306/mydb", max_ overflow=5) Base=de

the relationship and create the table separately, the entity table is the student table and the curriculum, the relational table is the elective table, where the relational table is based on the joint primary key and the curriculum primary key. 2 SQLAlchemy Table Relationship Usage 2.1 Pair of Multi Like a father can have more than one child, ClassParent(Base):__tablename__=' Parent 'Id=Column(Integer,Primary_key=True)Children= Relationship ( "chil

Tags: Content default method Pre tab Welcome flag bit Data Sheet impInstalling Flask-sqlalchemyPip Install Flask-sqlalchemyLoad SQLAlchemyAdd in hello.py From Flask.ext.sqlalchemy import SQLAlchemy Initialize settingsAdd in hello.py Set Database link Address 1 app.config['sqlalchemy_database_uri'mysql+mysqldb:// :@/charset=utf8' Create User Class1 classUser (db. Model):2 __tablename__='username' 3ID = db. Column (db. integer,primary_key=True)4Nam

keys to clarify the relationship between the two tables. Decide adderess.user relationship () sub-function backref () provides details for expressing the inverse relationship: Relationship () user.address Reference. A many-to-one inverse relationship is always a pair. For more details, refer to basic relrational patterns These two complementary relationships: address.user and user.addresses are called bidirectional relationships. This is A very critical feature of the

Label:I. SQLAlchemy-linked table operation 1. One-to-many Class group (Base): # One-to-many tables, which may contain multiple users __tablename__ = ' group ' nid = Column (Integer, Primary_key=true, Autoincrement=true) caption = Column (String ()) class User (Base): __tablename__ = ' user ' uid = Column (integer, Primary_key=true, autoincrement=true) name = Column (String ()) gid = column (integer, ForeignKey (' Group.n

, this is what all dislike orm people have in common). Now the various ORM frameworks are trying to use various methods to alleviate this block (Lazyload,cache), the effect is still very significant.SQLAlchemy InstallationPip Install SQLAlchemyPip Install PymysqlSQLAlchemy Basic UseCreate a table firstCREATE TABLE User ( ID INTEGER not NULL auto_increment, name varchar (+), password varchar), PRIMARY KEY (ID) )Use SQLAlchemy to achieve the same f

SQLAlchemy newspaper programmingerror:you must not use 8-bit bytestrings unless you use a text_factory the can interpret 8-bit by Testrings Errorpython2.x The most annoying is the coding problem, write down for later use.Workaround:1. At the beginning add:#encoding: Utf-82. Try Convert characters to Unicode formatUnicode (Str_name)This method sometimes appears: "Unicodedecodeerror: ' ASCII ' codec can ' t decode byte 0xe5 in position 108:ordinal not i

Tags: name error LTE expression Language RAM nbsp String filter InstallationIntroducedSQLAlchemy is an ORM framework based on Python implementations. The framework is built on the DB API, using relational object mappings for database operations, in short: converting Classes and objects to SQL, and then using the data API to execute SQL and get execution results.RoleHelp us quickly implement database operations using classes and objects.InstallationPIP3 Install

SQLAlchemy is a Python ORM framework.There is a flask-sqlalchemy extension in flask, which is convenient to use.1. Create a sqlalchemy model moduleTo create a models.py moduleWhen creating the model, first introduce the extension of Flask-sqlalchemy from Flask Import flask from Flask_sqlalchemy import SQLAlchemyThen in

Label: 1. Installation # pip Install SQLAlchemy# pip Install Pymysql 2. Creating an engine >>> from SQLAlchemy import create_engine>>> engine = Create_engine (' Mysql+pymysql://username:[email protected]_host:db_port/db_name ', pool_recycle =3600)pool_recycle Specifies the connection pool recovery time. Once the engine is initialized, you can connect to the database.3. Connect to the database >>> connectio

There are two kinds of return types for SQLAlchemy, one is model object and one is query collection (only partial fields). Both return results are from the same type Sqlalchemy.orm.query.Query So for the query to do the corresponding processing, let him return to a dict Class Alchemyjsonencoder (JSON. Jsonencoder): def default (self, obj): # Determines if the query is isinstance (obj, query): # defines a dictionary array F

The user table is described in the previous section, but in real life with the complexity of the problem the data stored in the database can not be so simple, let us imagine that there is another table, this table and user has a connection, can be mapped and query, then this table can store any number of e-mail addresses associated with an account. This connection is a typical 1-n (one-to-many) relationship in database theory, and a user table has a user that corresponds to N e-mail records. Be

Today, Clubot was upgraded, but after importing the data, Chinese characters are garbled, and one is to find the information to add the encoded information when the engine is created: Engine = Create_engine ("Mysql://root: @localhost: 3306/clubot?charset=utf8") But that's not OK, and then look at the table information: > Show CREATE TABLE Clubot_members;clubot_members | CREATE TABLE ' clubot_members ' (' id ' int (one) not null auto_increment, ' email ' varchar () DEFAULT NULL, ' Nick ' varcha

1. Install mysql-connector 2. DB = create_engine ('mysql + mysqlconnector: // root: liukesun @ localhost/testdb ') Gevent_sqlalchemy_test.py #! /Usr/bin/pythonimport geventfrom gevent import monkey # patches stdlib (including socket and SSL modules) to cooperate with other greenletsmonkey. patch_all () Import usertabledef get_user_data (): Print "Starting get_user_data" usertable. get_data () print "End get_user_data. "# jobs = [gevent. spawn (print_head, URL) for URL in URLs] jobs = [g

The Python Flask framework and Mysql database are used, and the database ORM adopts the SQLAlchemy framework. For solutions to Chinese garbled characters, see the following code snippet:@ App. route ('/', methods = ['get']) The code is as follows: Copy code Def index ():Games_origin = DimGameName. query. all ()Games = []For g in games_origin:Game = {}Game ['va

specify the encoding when creating the table in SQLAlchemy. So only in MySQL itself to find: > Show VARIABLES like "character%%"; +--------------------------+-----------------------------+ | variable_name | Value | +--------------------------+-----------------------------+ | character_set_client | UTF8 | | character_set_connection | UTF8 | | Character_set_database | Latin1 | | Character_set_filesystem | binary | | Character_set_results | UTF8 |

Tags: ase data lis root att children body parent ATISQLAlchemy uses the adjacency list pattern to represent the self-reference of a class. For example, for a class node self-reference: class Node (Base): __tablename__='node' ID=column (integer,primary_key=True) parent_id=column (Integer,foreignkey ('node.id')) data =column (String) children=relationship ('Node') For the structure as shown: Root--------------->child1 -------->child2---------->subchild1 ---------->subchild2 ---

ifFilter_type = = 1: Search= And_ (Gameroom.status ==1, Or_ (And_ (gameroom.white_user_id==user_id, Gameroom.active_player= = 1), And_ (gameroom.black_user_id==user_id, Gameroom.active_player==0 )))elifFilter_type = = 2: Search= And_ (Gameroom.status ==1, Or_ (And_ (gameroom.white_user_id==user_id, Gameroom.active_player==0), And_ (gameroom.black_user_id==user_id, Gameroom.active_player= = 1))) elifFilter_type = = 3: Search= Gameroom.create_by = =user_id db.session.query (gameroom). Filte

Tags: important primary key IKE class SQL and function HTTP NULLColumn Common parameters: Default: Defaults Nullable: Is it possible to have Primary_key: Whether the primary key Unique: Is it unique AutoIncrement: Whether to grow automatically OnUpdate: Functions that are executed when updating Name: Field mappings for this property in the database SQLAlchemy Common data types: Integer: Shaping float:

as Django, and you may be able to find some information on the web that appears to be what you need, but it is very likely that the modules used, the drivers will have different versions of the pits , from the wheel of patchwork to get together may appear a variety of error, this time you have an error to resolve the error, to check the cause of the error, to check the Patchwork module documentation, there are many versions of the MySQL driver, Pymysql, MYSQLDB, MySQL -connector, Mysql-connecto