SQL QUERY PAGE 18

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SQL QUERY

Query


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 the CUSTOMERS table having the following records: 
+----+----------+-----+-----------+----------+ 
| ID | NAME     | AGE | ADDRESS   | SALARY   | 
+----+----------+-----+-----------+----------+ 
|  1 | Ramakrishna  |  32 | Ahmedabad |  2000.00 | 
|  2 | Mdhu sudhan rao   |  25 | Delhi     |  1500.00 | 
|  3 | Sai  |  23 | Kota      |  2000.00 | 
|  4 | Kishor  |  25 | Mumbai    |  6500.00 | 
|  5 | Ranjith    |  27 | Bhopal    |  8500.00 | 
|  6 | Abhi    |  22 | MP        |  4500.00 | 
|  7 | Kumar     |  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 the following records: 
+----+----------+-----+-----------+----------+ 
| ID | NAME     | AGE | ADDRESS   | SALARY   | 
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+----+----------+-----+-----------+----------+ 
|  1 | Ramakrishna  |  32 | Ahmedabad |  2000.00 | 
|  2 | Mdhu sudhan rao   |  25 | Delhi     |  1500.00 | 
|  3 | Sai  |  23 | Kota      |  2000.00 | 
|  4 | Kishor  |  25 | Mumbai    |  6500.00 | 
|  5 | Ranjith    |  27 | Bhopal    |  8500.00 | 
|  7 | Kumar     |  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.