What is the difference between a schema and a table and a database?

Question

This is probably a n00blike (or worse) question. But I\'ve always viewed a schema as a table definition in a database. This is wrong or not entirely correct. I don\'t rememb

Answer 1

A relation schema is the logical definition of a table - it defines what the name of the table is, and what the name and type of each column is. It's like a plan or a blueprint. A database schema is the collection of relation schemas for a whole database.

A table is a structure with a bunch of rows (aka "tuples"), each of which has the attributes defined by the schema. Tables might also have indexes on them to aid in looking up values on certain columns.

A database is, formally, any collection of data. In this context, the database would be a collection of tables. A DBMS (Database Management System) is the software (like MySQL, SQL Server, Oracle, etc) that manages and runs a database.

Answer 2

Contrary to some of the above answers, here is my understanding based on experience with each of them:

• MySQL: database/schema :: table
• SQL Server: database :: (schema/namespace ::) table
• Oracle: database/schema/user :: (tablespace ::) table

Please correct me on whether tablespace is optional or not with Oracle, it's been a long time since I remember using them.

Answer 3

schema : database : table :: floor plan : house : room

Answer 4

In oracle Schema is one user under one database,For example scott is one schema in database orcl. In one database we may have many schema's like scott

Answer 5

A database contains one or more named schemas, which in turn contain tables. Schemas also contain other kinds of named objects, including data types, functions, and operators. The same object name can be used in different schemas without conflict; for example, both schema1 and myschema can contain tables named mytable. Unlike databases, schemas are not rigidly separated: a user can access objects in any of the schemas in the database he is connected to, if he has privileges to do so.

There are several reasons why one might want to use schemas:

To allow many users to use one database without interfering with each other.

To organize database objects into logical groups to make them more manageable.

Third-party applications can be put into separate schemas so they do not collide with the names of other objects.

Schemas are analogous to directories at the operating system level, except that schemas cannot be nested.

Official documentation can be referred https://www.postgresql.org/docs/9.1/ddl-schemas.html

Answer 6

A database schema is a way to logically group objects such as tables, views, stored procedures etc. Think of a schema as a container of objects. And tables are collections of rows and columns. combination of all tables makes a db.