Page 30 - Modular_V2.0_SQL_Flipbook

Let us change the marks of the student having 10002 as StudentID from 480 to 485 by using the
following command:

UPDATE Students SET Marks = 485 where Student_id = 10002;

DELETING RECORDS FROM A TABLE
The DELETE command is used to remove records from a table. The DELETE command can be used
in two ways:

Without WHERE clause With the WHERE clause
You can remove a specific record by using the WHERE clause with the DELETE command. If you use
the DELETE command without the WHERE clause, it will remove all the records from the table. Let us
use the DELETE command to remove the record of a student whose LastName is Kumar:

DELETE FROM Students WHERE Last_name="Kumar";
To remove all the records, following command is used:
Tech Funda
DELETE FROM Students;
USING DISTINCT CLAUSE
TRUNCATE TABLE empties a table
The DISTINCT clause is used with the SELECT
completely.
command to display the unique values of a
column.

The syntax of the DISTINCT clause is as
follows:
SELECT DISTINCT <column_name > FROM <table_name>;
For Example,

SELECT DISTINCT COST FROM OFFICE;
+------+
| COST | Hands On
+------+
| 20 |
+------+ Create an Orders table with columns: OrderID,
| 10 | CustomerID, and Product. Insert some records
+------+
| 45 | with duplicate product names. Then, write a query
+------+ using the DISTINCT clause to retrieve unique
| 120 |
+------+ product names from the Orders table.
| 30 |
+------+
USING OPERATORS

SQL statements consist of reserved words or symbols which are used to perform arithmetical
operations, comparisons, etc. These reserved words or symbols are called as ‘Operators’.
The three types of operators in SQL are:

Relational Operators
Boolean Operators

Special Operators
Let us learn about them.

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