Answer Posted / saraswathi muthuraman

Compost key :

More than one column will be used to create compst key

SQL> create table ts_250 (a number,b number,c number,
primary key(a,c));

Table created.

here column A and column C is used to create compst key.
U can't insert null value in both columns.
Only unique combination of column A and column B value can
be inserted.

Primary key :

Key will be created on a single column in table.

SQL> create table ts_251 (a number,b number,c number,
primary key(a));

Table created.


null value cann't be inserted into column a.
oracle will create a index
only unique value can be inserted into column a.
only one primary key can be created on a table

How to get a list of all tables in a database?

580

---

How do you backup a database in mysql?

580

---

How many columns is too many mysql?

474

---

What is use of mysql?

493

---

How to Recover a MySQL root password. Stop the MySQL server process. Start again with no grant tables. Login to MySQL as root. Set new password. Exit MySQL and restart MySQL server.

534

---

---

Which is better sqlite or mysql?

496

---

Explain what is mysql?

588

---

What is row?

570

---

What is pdo connection?

469

---

How do I install mysql on windows 10?

508

---

What is striped backup

1827

---

How to use 'mysql' to run sql statements?

529

---

What is the difference between procedure and function in mysql?

512

---

What's the difference between mysql and sql server?

476

---

How do you rename a table in mysql?

508

---