2. Subject Name Code Credit Hours
Database System COMP 219 3
DBMS Languages:
Types
Data Definition Language( DDL) Data Manipulation Language (DML)
storage definition language (SDL)
storage definition language (SDL)
Procedural DML
Non-Procedural DML
3. Subject Name Code Credit Hours
Database System COMP 219 3
DBMS Languages
– Used by the DBA and database designers to specify the
conceptual schema of a database.
– In many DBMSs, the DDL is also used to define internal and
external schemas (views).
– In some DBMSs, separate storage definition language (SDL) and
view definition language (VDL) are used to define internal and
external schemas.
• SDL is typically realized via DBMS commands provided to the
DBA and database designers
Data Definition Language (DDL):
4. Subject Name Code Credit Hours
Database System COMP 219 3
Data Manipulation Language (DDL):
• Data Manipulation Language (DML):
– Used to specify database retrievals and updates
– DML commands (data sublanguage) can be embedded in a
general-purpose programming language (AKA host
language), such as COBOL, C, C++, or Java.
– Alternatively, stand-alone DML commands can be applied
directly (called a query language).
DBMS Languages
5. Subject Name Code Credit Hours
Database System COMP 219 3
Data Definition Language (DDL):
– Used by the DBA and database designers to specify the
conceptual schema of a database.
– In many DBMSs, the DDL is also used to define internal and
external schemas (views).
– In some DBMSs, separate storage definition language (SDL)
and view definition language (VDL) are used to define
internal and external schemas.
• SDL is typically realized via DBMS commands provided to the DBA
and database designers
6. Subject Name Code Credit Hours
Database System COMP 219 3
Data Manipulation Language (DML)
• Language for accessing and manipulating the data organized
by the appropriate data model
– DML also known as query language
• Two classes of languages
– Procedural – user specifies what data is required and
how to get those data
– Declarative (nonprocedural) – user specifies what data is
required without specifying how to get those data
• SQL is the most widely used query language
7. Subject Name Code Credit Hours
Database System COMP 219 3
Data Definition Language (DDL)
• Specification notation for defining the database schema
Example: create table account (
account-number char(10),
balance integer)
• DDL compiler generates a set of tables stored in a data dictionary
• Data dictionary contains metadata (i.e., data about data)
– Database schema
– Data storage and definition language
• Specifies the storage structure and access methods used
– Integrity constraints
• Domain constraints
• Referential integrity (references constraint in SQL)
• Assertions
– Authorization
8. Subject Name Code Credit Hours
Database System COMP 219 3
DDL statements/commands in SQL
• Create table table name(list of attribute & their
datatypes);
• Create schema schema name authorization
author name;
• Drop schema schema name cascade/restrict;
• Drop table tablename cascade/restrict;
• Alter table talename add/drop
• Create view view name as (select …..)
