An information schema view is one of several methods SQL Server provides for obtaining metadata.
SQL Server supports a three-part naming convention when you refer to the current server. The ISO standard also supports a three-part naming convention. However, the names used in both naming conventions are different. The information schema views are defined in a special schema named INFORMATION_SCHEMA. This schema is contained in each database. Each information schema view contains metadata for all data objects stored in that particular database. The following table shows the relationships between the SQL Server names and the SQL standard names.
Database
Catalog
Schema
Object
user-defined data type
Domain
This name-mapping convention applies to the following SQL Server ISO-compatible views.
CHECK_CONSTRAINTS
REFERENTIAL_CONSTRAINTS
COLUMN_DOMAIN_USAGE
ROUTINES
COLUMN_PRIVILEGES
ROUTINE_COLUMNS
COLUMNS
SCHEMATA
CONSTRAINT_COLUMN_USAGE
TABLE_CONSTRAINTS
CONSTRAINT_TABLE_USAGE
TABLE_PRIVILEGES
DOMAIN_CONSTRAINTS
TABLES
DOMAINS
VIEW_COLUMN_USAGE
KEY_COLUMN_USAGE
VIEW_TABLE_USAGE
PARAMETERS
VIEWS
Also, some views contain references to different classes of data such as character data or binary data.
When you reference the information schema views, you must use a qualified name that includes the INFORMATION_SCHEMA schema name. For example:
INFORMATION_SCHEMA
SELECT TABLE_CATALOG, TABLE_SCHEMA, TABLE_NAME, COLUMN_NAME, COLUMN_DEFAULT FROM AdventureWorks.INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = N'Product'; GO