HSCI 709 SQL Data Definition Language. SQL Standard SQL-92 was developed by the INCITS Technical...
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Transcript of HSCI 709 SQL Data Definition Language. SQL Standard SQL-92 was developed by the INCITS Technical...
SQL Standard• SQL-92 was developed by the INCITS Technical Committee H2 on
Databases. • SQL-92 was designed to be a standard for relational database
management systems (RDBMSs)• Next Version: SQL3
– Will enhance SQL into a computationally complete language for the definition and management of persistent, complex objects.
• generalization and specialization hierarchies• multiple inheritance• user defined data types• triggers and assertions• support for knowledge based systems• recursive query expressions• and additional data administration tools• abstract data types (ADTs)• object identifiers• Methods• Inheritance, Polymorphism, Encapsulation, and all of the other facilities
normally associated with object data management
SQL Components
SQL
DCL DDL DML
DBA Activities
Create UsersDelete UsersGrant privilegesImplement AccessSecurity
RDBMS Structure
Create/Delete DBs
Create/Delete TablesAlter Tables
Data I/O
Create Record
Read Record
Update Record
Delete Record
"Create Table" Syntax
CREATE TABLE <myTable>
(<Field1> <DataType>, <Field2> <DataType>,…);
CREATE TABLE PAT
(PAT_ID INT, PAT_FM TEXT(20),PAT_LNM TEXT(35));
"Alter Table" Statement
• This statement can be used to:– Add new columns– Delete defined columns– Make a column the primary key– Change column data types– Change table names*– Make a column a foreign key– Add constraints to a column, e.g., indexing
* NOT SUPPORTED IN MS ACCESS
Adding a New Column
ALTER TABLE PAT ADD COLUMN PAT_DESCR MEMO;
ALTER TABLE <myTable> ADD COLUMN <NewField> <DataType>;
Creating a PK
ALTER TABLE PAT ADD PRIMARY KEY(PAT_ID);
ALTER TABLE <myTable> ADD PRIMARY KEY(<Field>);
Changing Data Types
ALTER TABLE <myTable> ALTER COLUMN <field> <newDataType>;
ALTER TABLE PAT ALTER COLUMN PAT_LNM TEXT(55);
Foreign KeysPAT
PAT_ID INT
PAT_FNM TEXT(20)PAT_LNM TEXT(35)
CLNCIAN
CLNCIAN_ID INT
CLNCIAN_NM TEXT(250)PAT_ID
Foreign Keys
CREATE TABLE CLNCIAN (CLNCIAN_ID INTEGER PRIMARY KEY, CLNCIAN_NM TEXT (55), PAT_ID INT, CONSTRAINT FKPatId FOREIGN KEY (PAT_ID) REFERENCES PAT);
PAT
PAT_ID INT
PAT_FNM TEXT(20)PAT_LNM TEXT(35)
CLNCIAN
CLNCIAN_ID INT
CLNCIAN_NM TEXT(250)PAT_ID