Download Structured Query Language

Structured Query Language
Brief History
• Developed in early 1970 for relational data
model:
– Structured English Query Language (SEQUEL)
– Implemented with IBM System R
• 1987 first ISO standard version
• 1992 SQL 2
• 1999 SQL 3
– Object-relational model
• 2003:SQL 2003
– SQL/XML
• Products: DB2, Oracle, MS SQL, MySQL
Oracle Account
• Server: libra.sfsu.edu
• Telnet: libra.sfsu.edu
• How to use Oracle:
– http://www.sfsu.edu/~helpdesk/docs/using/usingoracle.htm
• Basic Unix commands:
– http://www.sfsu.edu/~helpdesk/docs/using/unixcmd.htm
• You may also use MySQL for assignments and project.
Other DBMS
• MySQL 5.0:
– http://dev.mysql.com/downloads/
• MS SQL Server 2005 Express:
– http://msdn.microsoft.com/vstudio/express/sql/
download/
Language Overview
• Three major components:
– Data definition language
• Create Table
– Data manipulation language
• Updating database:
– Insert, Delete, Update
• Query database:
– Select
– Data control language (DCL)
• Help DBA control the database:
– Grant/revoke privileges to access the database, creating procedures,
etc.
• Interface with database:
– Entering command interactively at the DBMS command prompt.
– Embedded in a procedural language
Data Definition Language
• SQL Identifiers
– Character set: A-Z, a-z, 0-9, _
– <= 128 characters
– Start with a letter
– Cannot contain spaces
SQL Data Types
• Boolean
– True, False, Unknown (for Null)
• Character
– Fixed length: CHARACTER(n), CHAR(n), CHAR – default to 1 character
– Varying length:
• CHARACTER VARYING(n): Maximum length is n
• VARCHAR(n)
• Numeric
– NUMERIC(i,j), DECIMAL(i,j), DEC(i,j)
– INTEGER, INT, SMALLINT – up to 32767
– FLOAT, REAL, DOUBLE PRECISION
• Date:
– DATE
– TIME
– TIMESTAMP
• Large objects:
– CHARACTER LARGE OBJECT
– BINARY LARGE OBJECT
CREATE TABLE
• CREATE TABLE tableName(fields and
data type separated by commas);
• Ex.
– CREATE TABLE employee(
eid CHAR(5),
ename VARCHAR(40),
sex CHAR,
salary NUMERIC(9,2),
hire_Date DATE);
Integrity Enhancement Feature
• Required data: NOT NULL
– eid CHAR(5) NOT NULL,
• Default value:DEFAULT
sex CHAR DEFAULT ‘M’,
• Field domain: CHECK(condition)
– salary NUMERIC(9,2) CHECK (salary >= 100 AND salary
<=10000),
– sex CHAR DEFAULT ‘M’ CHECK (sex in (‘M’,’F”)),
• PRIMARY KEY
– PRIMARY KEY(sid)
– PRIMARY KEY(sid, cid)
• Unique – allow null value, the PRIMARY KEY constraint
does not allow null.
– ESSN CHAR(9) UNIQUE
– CREATE TABLE employee(
eid CHAR(5) PRMARY KEY,
ename VARCHAR(40),
sex CHAR DEFAULT ‘M’ CHECK (sex in (‘M’,’F”)),
salary NUMERIC(9,2),
hire_Date DATE);
• create table orderdetail
• (oid char(3), cid char(5), qty numeric(5,2),
• primary key (oid,cid));
ALTER TABLE
• ADD/Modify/DROP COLUMN a new field
from a table.
• Ex.
ALTER TABLE employee
ADD phone CHAR(8);
ALTER TABLE employee
Modify phone CHAR(9);
ALTER TABLE employee
DROP COLUMN Phone;
Adding Constraints with the ALTER
TABLE command
• Constraints:
– PRIMARY KEY, CHECK, UNIQUE
• PRIMARY KEY:
– ALTER TABLE tablename
– ADD CONSTRAINT constraintname
– PRIMARY KEY (columnname);
• CHECK
– ALTER TABLE tablename
– ADD CONSTRAINT constraintname
– CHECK (criteria);
Examples
ALTER TABLE emp
ADD CONSTRAINT empkey PRIMARY KEY (empid);
ALTER TABLE emp
ADD CONSTRAINT validSalary CHECK (salary between 100 AND 20000);
Note: Constraints information are stored in table: USER_CONSTRAINTS. You
can use the DESCRIBE command to show fields in this table.
Dropping Constraints
ALTER TABLE tablename
DROP CONSTRAINT constraintname;
Disable/Enable Constraints
• ALTER TABLE tablename
• DISABLE CONSTRAINT constraintname;
• ALTER TABLE tablename
• ENABLE CONSTRAINT constraintname;
Creating Table Through SubQuery
• CREATE TABLE tableName
• AS (Select query)
• Ex.
– CREATE TABLE newEmp
– AS (SELECT empid, ename,salary FROM
emp);
Renaming a Table
• Rename oldName to newName
Removing a Table
• DROP TABLE tableName
SQL Insert Command
INSERT INTO tableName VALUES (field values separated
by commas);
INSERT INTO tableName (Column names separated by
commas)VALUES (field values separated by commas);
Ex 1. Customer table with CID, CNAME, CITY, RATING.
a. INSERT INTO CUSTOMER VALUES (‘C1’, ‘SMITH’, ‘SF’, ‘A’);
b. INSERT INTO CUSTOMER (CID, CNAME,RATING) VALUES
(‘C1’, ‘SMITH’, ‘A’);
Record with Date Field
• Oracle date format:
– ‘dd-mmm-yyyy’
• Example:
• insert into orders values('O7','c2','s1','10-oct-2007');
Inserting records from an existing
table
• INSERT INTO stu2
• (select * from student);
SQL Delete Command
DELETE FROM tableName [WHERE criteria];
Ex 1. Delete a record from the Customer table.
DELETE FROM CUSTOMER WHERE CID = ‘C1’;
SQL Update Command
UPDATE tableName SET field = new value [WHERE criteria];
Ex 1.
UPDATE CUSTOMER SET RATING = ‘A’ WHERE CID=‘C1’;
Ex 2.
UPDATE CUSTOMER SET CITY = ‘SF’, RATING = ‘A’ WHERE CID=‘C1’;
Dealing with Null
• Null is a key word. We can use Null in the
INSERT, UPDATE, and DELETE command.
• Use IS NULL (or IS NOT NULL) in a criteria.
• Examples:
– INSERT INTO emp VALUES
(‘e95’,’June’,’f’,NULL,5000);
– UPDATE emp SET salary=null where empid=‘e99’;
– SELECT * FROM emp WHERE salary IS NULL;
– SELECT * FROM emp WHERE salary= NULL (not
working);