Answer Posted / ambresh pratap srivastava

primary key is combination of column which uniquely specify a row.A table have at most one primary key. primary key creates Clustered Index.A primary key column allows no row having null value

Unique key can uniquely identify each row in a table and is closely related to super key concept.A unique key comprises a single column or a group of column.A unique key column allows only one row having null value.Unique key creates unclustered Index.

21. Using a set operator, display the client number of all clients who have ever placed an order and whose whose name does not contain the string Sm.

2165

---

How to add another datafile to a tablespace?

1088

---

Explain what are clusters?

1155

---

What are the execution control statements in oracle?

1130

---

Difference between oracle's plus (+) notation and ansi join notation?

1160

---

Difference between the “verify” and “feedback” command?

1427

---

How to define a record variable to store a table row?

1113

---

How can we find out the duplicate values in an oracle table?

1119

---

Explain index?

1307

---

What is meant by recursive hints in oracle?

1130

---

Give syntax for SQL and ORACLE joins.

1144

---

What happens to the current transaction if the session is killed?

1035

---

What is set verify off in oracle?

1157

---

How to return top 5 rows in oracle?

1112

---

What are the types of trigger in oracle?

1028

---