Podcast
Questions and Answers
What is JSON an abbreviation for?
What is JSON an abbreviation for?
JSON objects can have object IDs.
JSON objects can have object IDs.
False
What are the key-value pairs in JSON objects?
What are the key-value pairs in JSON objects?
attribute name and value
JSON is widely used for data exchange in modern applications, especially in _______________ services.
JSON is widely used for data exchange in modern applications, especially in _______________ services.
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What is the type of data structure used to store multiple values in JSON?
What is the type of data structure used to store multiple values in JSON?
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SQL extensions are not available for JSON data types.
SQL extensions are not available for JSON data types.
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Match the JSON data type with its description:
Match the JSON data type with its description:
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What is the main advantage of using semi-structured data in data exchange?
What is the main advantage of using semi-structured data in data exchange?
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XML is a relatively new notation for semi-structured data.
XML is a relatively new notation for semi-structured data.
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What are some examples of semi-structured data models?
What are some examples of semi-structured data models?
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XML stands for ______________________ Markup Language.
XML stands for ______________________ Markup Language.
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Why may the relational model's requirement of atomic data types be an overkill in some applications?
Why may the relational model's requirement of atomic data types be an overkill in some applications?
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Match the following semi-structured data models with their characteristics:
Match the following semi-structured data models with their characteristics:
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What is a characteristic of semi-structured data models?
What is a characteristic of semi-structured data models?
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JSON is a document format.
JSON is a document format.
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What is the purpose of JSON_agg aggregate function in PostgreSQL?
What is the purpose of JSON_agg aggregate function in PostgreSQL?
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In JSON, character encoding is strictly _______________.
In JSON, character encoding is strictly _______________.
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Match the following data types with their descriptions:
Match the following data types with their descriptions:
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JSON has namespaces.
JSON has namespaces.
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What is an example of an array database?
What is an example of an array database?
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In JSON, the _______________ function is used to generate JSON from relational data.
In JSON, the _______________ function is used to generate JSON from relational data.
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What is the purpose of an object-relational mapping (ORM) system?
What is the purpose of an object-relational mapping (ORM) system?
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What is a characteristic of JSON?
What is a characteristic of JSON?
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Study Notes
JSON
- JSON is a minimal, textual, language-independent representation widely used for data exchange.
- It is a notation for representing data in a format that is easy for humans to read and write.
- JSON is versionless and does not have namespaces, it uses context to avoid ambiguity.
- Character encoding is strictly Unicode.
- JSON is not a document format and is not a markup language.
Generating JSON from Relational Data
- JSON can be generated from relational data using object-relational mapping.
- Example: json.build_object(‘ID’, 12345, ‘name’, ‘Einstein’)
- JSON collections can be created using aggregation functions such as json_agg in PostgreSQL.
Semi-Structured Data Models
- Semi-structured data models have flexible schemas, allowing each tuple to have a different set of attributes.
- They support multivalued data types, such as sets, multisets, and key-value maps.
- Examples: set of interests {‘basketball, ‘La Liga’, ‘cooking’, ‘anime’, ‘jazz’}, key-value map {(brand, Apple), (ID, MacBook Air), (size, 13), (color, silver)}.
- Operations on maps: put(key, value), get(key), delete(key).
Arrays
- Arrays are widely used for scientific and monitoring applications.
- Examples: readings taken at regular intervals can be represented as an array of values instead of (time, value) pairs.
- Array databases provide specialized support for arrays, such as compressed storage and query language extensions.
- Examples of array databases: Oracle GeoRaster, PostGIS, SciDB.
Object-Relational Data Model
- The object-relational data model provides a richer type system with complex data types and object orientation.
- Applications are often written in object-oriented programming languages, which do not match the relational type system.
- Approaches for integrating object-orientation with databases include:
- Building an object-relational database by adding object-oriented features to a relational database.
- Automatically converting data between programming language models and relational models using object-relational mapping.
- Building an object-oriented database that natively supports object-oriented data and direct access from programming languages.
Object-Relational Database Systems
- User-defined types can be created using object-relational database systems.
- Table types can be created using array and multiset data types.
- Example: create type Person (ID varchar(20) primary key, name varchar(20), address varchar(20)) ref from(ID); create table people of Person;
Type and Table Inheritance
- Type inheritance allows for the creation of new types based on existing types.
- Example: create type Student under Person (degree varchar(20)); create type Teacher under Person (salary integer);
- Table inheritance syntax in PostgreSQL and Oracle: create table students (degree varchar(20)) inherits people; create table teachers (salary integer) inherits people;
Reference Types
- Creating reference types: create type Person (ID varchar(20) primary key, name varchar(20), address varchar(20)) ref from(ID); create table people of Person;
- Using references in path expressions: select head->name, head->address from departments;
Object-Relational Mapping
- Object-relational mapping (ORM) systems allow for the specification of mapping between programming language objects and database tuples.
- Automatic creation of database tuples upon creation of objects.
- Automatic update/delete of database tuples when objects are updated/deleted.
- Interface to retrieve objects satisfying specified conditions.
- Examples: Hibernate ORM for Java, Django ORM for Python.
XML
- XML: Extensible Markup Language.
- Earlier generation notation, still used extensively.
- XML uses tags to mark up text.
- Example: Intro.to Computer Science “..” specifies the parent.doc(name) returns the root of a named document.
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Description
This quiz covers the basics of JSON, including its features, versions, and how it is used to represent data. It also touches on generating JSON from relational data.
