Online Toy Store Management System - Sql (with Answers)

Online Toy Store Management System

CREATE TABLE TOY_STORE_PRASANTH

(TOY_STORE_ID NUMBER(3) PRIMARY KEY,

TOY_STORE_NAME VARCHAR2(30) NOT NULL,

CITY VARCHAR2(30) DEFAULT 'Delhi',

PHONENUMBER NUMBER(10) NOT NULL UNIQUE,

STORE_OPENING_TIME TIMESTAMP CHECK(STORE_OPENING_TIME < '8:00:00') ,

STORE_CLOSING_TIME TIMESTAMP CHECK(STORE_CLOSING_TIME > '10:00:00'))

Table Created.

Constraints used:

PRIMARY KEY:

     The PRIMARY KEY constraint uniquely identifies each record in a database table. Primary keys must contain UNIQUE values. A primary key column cannot contain NULL values. Most tables should have a primary key, and each table can have only ONE primary key. A table can have only one primary key, which may consist of single or multiple fields. When multiple fields are used as a primary key, they are called a composite key.

NOT NULL:

     We select only the records with no NULL values. Always use IS NULL to look for NULL values.

DEFAULT Constraint:

     The DEFAULT constraint is used to insert a default value into a column.The default value will be added to all new records, if no other value is specified.

UNIQUE:

     The UNIQUE constraint uniquely identifies each record in a database table.The UNIQUE and PRIMARY KEY constraints both provide a guarantee for uniqueness for a column or set of columns. A PRIMARY KEY constraint automatically has a UNIQUE constraint defined on it. 

Note that you can have many UNIQUE constraints per table, but only one PRIMARY KEY constraint per table.

TIMESTAMP:

     TIMESTAMP - format: YYYY-MM-DD HH:MI:SS