DBMS Support a variety of users and provides appropriate languages and interface or each category of users.Here are some languages that are provided by DBMS:
1) Data Definition Language (DDL): This Language is used define data structures and specially database schemas. these statements are used to create, alter, or drop data structures. ALTER ,CREATE ,DROP are some examples of DDL.
2) Storage Definition Language (SDL): This language is used to define internal schema. It defines that what will be the Physical structure of database, How many bites per field will be used, what will be the order of fields, and how records will be accesses etc.
3) View Definition Language (VDL): This language is used to specify user views and their mapping to conceptual schema. It defines the subset of records available to classes of users. It creates virtual tables and the view appears to users like conceptual level.It specifies user interfaces.
4) Data Manipulation Language (DML): It is used at conceptual level and external level and is used to perform operations like Query, Delete Update or Insert.Read Only Queries are also sometimes considered as component of DML.It modifies the data but not schema or database objects. These languages are further divided into two types:
a) Procedural Programming: It simply contains series of computational steps to be carried out.any procedure might be called at any point during program execution.
b) Declarative Programming: It Describes the logic of computation without describing its control flow.
Whereas Standard SQL Defines Following Languages:
1) Conceptual Level DDL
2) Conceptual Level DML
3) External Level DDL (Views are defined as queries with names)
4) External Level DML
NO Storage Definition Language.
1) Data Definition Language (DDL): This Language is used define data structures and specially database schemas. these statements are used to create, alter, or drop data structures. ALTER ,CREATE ,DROP are some examples of DDL.
2) Storage Definition Language (SDL): This language is used to define internal schema. It defines that what will be the Physical structure of database, How many bites per field will be used, what will be the order of fields, and how records will be accesses etc.
3) View Definition Language (VDL): This language is used to specify user views and their mapping to conceptual schema. It defines the subset of records available to classes of users. It creates virtual tables and the view appears to users like conceptual level.It specifies user interfaces.
4) Data Manipulation Language (DML): It is used at conceptual level and external level and is used to perform operations like Query, Delete Update or Insert.Read Only Queries are also sometimes considered as component of DML.It modifies the data but not schema or database objects. These languages are further divided into two types:
a) Procedural Programming: It simply contains series of computational steps to be carried out.any procedure might be called at any point during program execution.
b) Declarative Programming: It Describes the logic of computation without describing its control flow.
Whereas Standard SQL Defines Following Languages:
1) Conceptual Level DDL
2) Conceptual Level DML
3) External Level DDL (Views are defined as queries with names)
4) External Level DML
NO Storage Definition Language.
No comments:
Post a Comment