The SQL 
DELETE Query is used to delete the existing records  from a table.
You can use WHERE clause with DELETE query to delete selected rows,  otherwise all the records would be deleted.
Syntax:
The basic syntax of DELETE query with WHERE clause is as follows:
| DELETE FROM table_name
WHERE [condition]; | 
You can combine N number of conditions using AND or OR operators.
Example:
Consider CUSTOMERS table is having following records:
| +----+----------+-----+-----------+----------+
| ID | NAME     | AGE | ADDRESS   | SALARY   |
+----+----------+-----+-----------+----------+
|  1 | Ramesh   |  32 | Ahmedabad |  2000.00 |
|  2 | Khilan   |  25 | Delhi     |  1500.00 |
|  3 | kaushik  |  23 | Kota      |  2000.00 |
|  4 | Chaitali |  25 | Mumbai    |  6500.00 |
|  5 | Hardik   |  27 | Bhopal    |  8500.00 |
|  6 | Komal    |  22 | MP        |  4500.00 |
|  7 | Muffy    |  24 | Indore    | 10000.00 |
+----+----------+-----+-----------+----------+ | 
Following is an example which would DELETE a customer whose ID is 6:
| SQL> DELETE FROM CUSTOMERS
WHERE ID = 6; | 
Now CUSTOMERS table would have following records:
| +----+----------+-----+-----------+----------+
| ID | NAME     | AGE | ADDRESS   | SALARY   |
+----+----------+-----+-----------+----------+
|  1 | Ramesh   |  32 | Ahmedabad |  2000.00 |
|  2 | Khilan   |  25 | Delhi     |  1500.00 |
|  3 | kaushik  |  23 | Kota      |  2000.00 |
|  4 | Chaitali |  25 | Mumbai    |  6500.00 |
|  5 | Hardik   |  27 | Bhopal    |  8500.00 |
|  7 | Muffy    |  24 | Indore    | 10000.00 |
+----+----------+-----+-----------+----------+ | 
If you want to DELETE all the records from CUSTOMERS table, you do  not need to use WHERE clause and DELETE query would be as follows:
| SQL> DELETE FROM CUSTOMERS; | 
Now CUSTOMERS table would not have any record.
 
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