Page 41 - Modular_V2.0_SQL_Flipbook

+-----------+
| New Marks |
+-----------+
| 17.40 |
+-----------+
| 13.20 |
+-----------+
This query will show the 20 percent of marks and display the result in New Marks column

Select 3.1.416 as pi;
This expression can help to set the value of pi as 3.1416.

Let's take some more examples.
Table-STUDENT

Stu_id Stu_name Age Class Marks
101 Rahim 18 XII 87

102 Raja 19 XII 66
103 Riya 18 XII 55

Table-FEE

Stu_id Fees Fine Transport
101 12000 100 2000

102 13000 500 3000
103 12000 100 5000

Similarly, table aliases can be used to shorten the names of big table names if in use.
SELECT S.stu_name, F.Fee FROM STUDENT AS S, FEE AS F

WHERE S.Stu_id = F.Stu_id;
In the above example S and F are used instead of Student and Fee Table.

PERFORMING CALCULATIONS IN QUERIES

We can easily perform basic queries in MySQL using functions. The functions are called aggregate
functions or group functions.

1. COUNT(): This function helps to count the number of records or values in a specified column/expression.

2. AVG(): This function helps to find the average of any numeric field in the table.
3. MAX(): This function is helpful in finding maximum value in the given set of values.

4. MIN(): This function help in finding the minimum value in the given set of values.

5. SUM(): This function finds the sum of values under a specific column.

Examples to show the working of MIN() and MAX() function.:
SELECT MIN(Fees) AS "min(fees)" FROM FEE;

SELECT MAX(Fees) AS "max(fees)" FROM FEE;

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