ORM Querying Guide

この節では、:term:`2.0 style`を使用してSQLAlchemy ORMでクエリを発行する方法の概要を説明します。

このセクションの読者は SQLAlchemy Unified Tutorial のSQLAlchemyの概要に精通しているはずです。特に、ここでの内容のほとんどは Using SELECT Statements の内容を拡張したものです。

For users of SQLAlchemy 1.x

SQLAlchemy 2.xシリーズでは、ORM用のSQL SELECT文はCoreで使用されているものと同じ select() 構文を使用して構築され、 Session.execute() メソッドを使用して Session の観点から呼び出されます( ORM-Enabled INSERT, UPDATE, and DELETE statements 機能で使用されるようになった update() および delete() 構文も同様です)。しかし、レガシーの Query オブジェクトは、より”オールインワン”オブジェクトとして同じ手順を実行しますが、この新しいシステムの薄いファサードとして引き続き使用可能であり、すべてのクエリを大規模に置き換えることなく、1.xシリーズで構築されたアプリケーションをサポートします。このオブジェクトのリファレンスについては、 Legacy Query API を参照してください。

• Writing SELECT statements for ORM Mapped Classes
  • Selecting ORM Entities and Attributes
    • Selecting ORM Entities
    • Selecting Multiple ORM Entities Simultaneously
    • Selecting Individual Attributes
    • Grouping Selected Attributes with Bundles
    • Selecting ORM Aliases
    • Getting ORM Results from Textual Statements
    • Selecting Entities from Subqueries
    • Selecting Entities from UNIONs and other set operations
  • Joins
    • Simple Relationship Joins
    • Chaining Multiple Joins
    • Joins to a Target Entity
    • Joins to a Target with an ON Clause
    • Combining Relationship with Custom ON Criteria
    • Using Relationship to join between aliased targets
    • Joining to Subqueries
    • Joining to Subqueries along Relationship paths
    • Subqueries that Refer to Multiple Entities
    • Setting the leftmost FROM clause in a join
  • Relationship WHERE Operators
    • EXISTS forms: has() / any()
    • Relationship Instance Comparison Operators
• Writing SELECT statements for Inheritance Mappings
  • SELECTing from the base class vs. specific sub-classes
  • Using selectin_polymorphic()
    • Applying selectin_polymorphic() to an existing eager load
    • Applying loader options to the subclasses loaded by selectin_polymorphic
    • Configuring selectin_polymorphic() on mappers
  • Using with_polymorphic()
    • Filtering Subclass Attributes with with_polymorphic()
    • Using aliasing with with_polymorphic
    • Configuring with_polymorphic() on mappers
  • Joining to specific sub-types or with_polymorphic() entities
    • Eager Loading of Polymorphic Subtypes
  • SELECT Statements for Single Inheritance Mappings
    • Optimizing Attribute Loads for Single Inheritance
  • Inheritance Loading API
    • with_polymorphic()
    • selectin_polymorphic()
• ORM-Enabled INSERT, UPDATE, and DELETE statements
  • ORM Bulk INSERT Statements
    • Getting new objects with RETURNING
    • Using Heterogeneous Parameter Dictionaries
    • ORMバルクインサート文でのNULL値の送信
    • Bulk INSERT for Joined Table Inheritance
    • ORM Bulk Insert with SQL Expressions
    • Legacy Session Bulk INSERT Methods
    • ORM “upsert” Statements
  • ORM Bulk UPDATE by Primary Key
    • Disabling Bulk ORM Update by Primary Key for an UPDATE statement with multiple parameter sets
    • Bulk UPDATE by Primary Key for Joined Table Inheritance
    • Legacy Session Bulk UPDATE Methods
  • ORM UPDATE and DELETE with Custom WHERE Criteria
    • Important Notes and Caveats for ORM-Enabled Update and Delete
    • Selecting a Synchronization Strategy
    • Using RETURNING with UPDATE/DELETE and Custom WHERE Criteria
    • UPDATE/DELETE with Custom WHERE Criteria for Joined Table Inheritance
    • Legacy Query Methods
• Column Loading Options
  • Limiting which Columns Load with Column Deferral
    • Using load_only() to reduce loaded columns
    • Using defer() to omit specific columns
    • Using raiseload to prevent deferred column loads
  • Configuring Column Deferral on Mappings
    • Using deferred() for imperative mappers, mapped SQL expressions
    • Using undefer() to “eagerly” load deferred columns
    • Loading deferred columns in groups
    • Undeferring by group with undefer_group()
    • Undeferring on wildcards
    • Configuring mapper-level “raiseload” behavior
  • Loading Arbitrary SQL Expressions onto Objects
    • Using with_expression() with UNIONs, other subqueries
  • Column Loading API
    • defer()
    • deferred()
    • query_expression()
    • load_only()
    • undefer()
    • undefer_group()
    • with_expression()
• Relationship Loading Techniques
  • Summary of Relationship Loading Styles
  • Configuring Loader Strategies at Mapping Time
  • Relationship Loading with Loader Options
    • Adding Criteria to loader options
    • Specifying Sub-Options with Load.options()
  • Lazy Loading
    • Preventing unwanted lazy loads using raiseload
  • Joined Eager Loading
    • The Zen of Joined Eager Loading
  • Select IN loading
  • Subquery Eager Loading
  • What Kind of Loading to Use ?
  • Polymorphic Eager Loading
  • Wildcard Loading Strategies
    • Per-Entity Wildcard Loading Strategies
  • Routing Explicit Joins/Statements into Eagerly Loaded Collections
    • Using contains_eager() to load a custom-filtered collection result
  • Relationship Loader API
    • contains_eager()
    • defaultload()
    • immediateload()
    • joinedload()
    • lazyload()
    • Load
    • noload()
    • raiseload()
    • selectinload()
    • subqueryload()
• ORM API Features for Querying
  • ORM Loader Options
  • ORM Execution Options
    • Populate Existing
    • Autoflush
    • Fetching Large Result Sets with Yield Per
    • Identity Token
• Legacy Query API
  • The Query Object
    • Query
  • ORM-Specific Query Constructs