Answer Posted / karthicksharma

As said earlier UNIQUE is a constraint and can be used
during a table creation to prevent duplication of data .

-----------------------------------------------------
CREATING A TABLE USING UNIQUE CONSTRAINT:
=================================================

eg:
SQL> create table empl1 (name varchar2(15),no number(5)
unique);

Table created.

-----------------------------------------------------

So from this it is clearly implied that UNIQUE constraint
is used to prevent INSERTION AS WELL AS RETRIVAL of non-
duplicate data.

whereas DISTINCT clause can only be used for RETRIVAL of
non-duplicate data.

Whereas DISTINCT is a clause and cannot be used during a
table creation to limit the duplication of data.

-----------------------------------------------------
CREATING A TABLE USING DISTINCT CLAUSE:
===========================================
eg:
create table empl2(name varchar2(15),no number(5) distinct)
*
ERROR at line 1:
ORA-00907: missing right parenthesis

-----------------------------------------------------

How many scalar data types are supported in pl/sql?

982

---

How to avoid using cursors? What to use instead of cursor and in what cases to do so?

1134

---

Why primary key is required?

943

---

what happens when the column is set to auto increment and you reach the maximum value for that table? : Sql dba

979

---

What is %rowtype in pl sql?

933

---

Is pl sql a scripting language?

977

---

How do I enable sql encryption?

975

---

How can we avoid duplicating records in a query?

933

---

how to use regular expression in pattern match conditions? : Sql dba

975

---

Do stored procedures prevent sql injection?

925

---

What is the most important ddl statements in sql are?

952

---

How can we store rows in PL/SQL using array?

1167

---

Is it possible for a table to have more than one foreign key?

989

---

Can we have two clustered index on a table?

976

---

Can we join same table in sql?

966

---