What are the types of constraints avaialable in oracle?

Correct Answer: Dropped tables can be recovered using DROP TABLE flashback It works the way recycle bin works Example: FLASHBACK TABLE EMPLOYEE TO BEFORE DROP; The most recently dropped table with that original name is retrieved from the recycle bin, with its original name

Correct Answer: New column can be added using the ALTER TABLE command as shown below: Example: ALTER TABLE employee ADD DateOfBirth date

Correct Answer: When any file is attempted to edit without any arguments (example ed or edit), the last SQL command is saved in AFIEDTBUF, It acts like a default buffer file for edit commands

Correct Answer: 1) START- Used to run a SQL script 2) ACCEPT- Accepts input from user 3) GET- Gets the sql file from user to place in buffer 4) LIST- Displays the last command executed 5) RUN- Used to list and run the command in buffer 6) SHOW- Shows the environment settings Example: SHOW PAGESIZE

Correct Answer: - ABS(number) Returns the absolute positive value of an expression Syntax: ABS(expression) Example: SELECT ABS(-10), ABS(00), ABS(10) Output: 10 0 10 - CEIL(number) Returns the smallest integer greater than, or equal to, the specified numeric expression Syntax: CEILING(expression) Example: SELECT CEILING($22345), CEILING($-22345), CEILING($00) Output: 22400 -22300 000 - FLOOR(number) Returns the largest integer less than, or equal to, the specified numeric expression Syntax: FLOOR(expression) Example: SELECT FLOOR($22345), CEILING($-22345), CEILING($00) Output: 22300 -22400 000 - MOD(number, divisor) Returns the remainder of the division from 2 integer values Syntax: MOD(dividend, divisor) Example: SELECT MOD(20,3) Output: 2 - POWER(number, power) Returns the exponential value for the numeric expression Syntax: POWER(number, power) Example: SELECT POWER(20, 30) Output: 80 - SIGN(number) Returns the sign ie positive or negative value for the numeric expression It returns -1 for negative expressions, a value of 0 for zero Syntax: SIGN(number) Example: SELECT SIGN(4) Output: 1 - ROUND(number, precision) Returns the numeric value rounded off to the next value specified Syntax: ROUND(number, number of places) Example: SELECT ROUND(13456, 2) - SQRT(number) Returns the square root value of the expression Syntax: SQRT(number) Example: SELECT SQRT(40) Output: 20 - TRUNC(number, precision) Returns a numeric value that truncate to the specific places Syntax: TRUNCATE(number,places) Example: SELECT TRUNCATE(13456, 2) Output: 134

Correct Answer: Oracle check constraint is used to ensure that before inserting the data in the database, it is validated and checked for the condition Example: Below, the constraint is that the id has to be between 0 and 1000 create table employee ( id number check (id between 0 and 1000), Name varchar(200) );

Correct Answer: Oracle NOT NULL is used on a column to ensure that the value for that column can never be NULL Example: Below, the constraint is that the id should never be NULL If it is, oracle throws an error create table employee ( id number NOT NULL, Name varchar(200) );

Correct Answer: Primary key constraint ensures that the column(s) always has a unique value to identify the record Example: Below, the primary key is created for column id with name prim_id create table employee ( id number NOT NULL, Name varchar(200) Constraint prim_id primary key(id) );

Correct Answer: A foreign key is a reference to another table It is used to establish relationships between tables For example, relationship between employee and professor table One employee can have multiple professors The Primary key of employee becomes foreign key of professor Example: create table employee ( id number NOT NULL, professor_id NOT NULL, Name varchar(200) Constraint prim_id Foreign key(id) references professor(professor_id) );

Correct Answer: A unique constraint on a column uniquely identifies the record by a combination of one or more fields Few unique constraint fields can have a NULL value as long as the combination of values is unique Example: create table employee ( id number NOT NULL, dob DATE, professor_id NOT NULL, Name varchar(200) Constraint id_unique UNIQUE(id,dob) );