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SQL Aggregate Functions First

                         

SQL Aggregate Function First, that performs calculation of data. The SQL aggregate function retrieve a single value, by calculate from values in a column. 

  Understand with Example

The Tutorial illustrate an example from SQL Aggregate Functions First. The Example create a table 'Stu_Table'. The create table keyword create a table 'Stu_Table' with field attribute like 'Stu_Id','Stu_Name' and 'Stu_Class' .Each fields in the table have different data type respectively.

create the Table Stu_Table

SQL statement to create table:

create table Stu_Table(Stu_Id integer(2), Stu_Name varchar(15), Stu_Class  varchar(10));

Insert data into Stu_Table

Insert into keyword add the records or rows to the table 'Stu_Table'.

SQL statement to insert data into table:

insert into Stu_Table values(1,'Komal',10);
insert into Stu_Table values(2,'Ajay',10);
insert into Stu_Table values(3,'Rakesh',10);
insert into Stu_Table values(4,'Bhanu',10);
insert into Stu_Table values(5,'Santosh',10);
insert into Stu_Table values(6,'Tanuj',10);
insert into Stu_Table values(1,'Komal',10);
insert into Stu_Table values(2,'Ajay',10);
insert into Stu_Table values(3,'Rakesh',10);
insert into Stu_Table values(4,'Bhanu',10);
insert into Stu_Table values(5,'Santosh',10);
insert into Stu_Table values(2,'Ajay',10);
insert into Stu_Table values(3,'Rakesh',10);
insert into Stu_Table values(4,'Bhanu',10);
insert into Stu_Table values(5,'Santosh',10);
insert into Stu_Table values(1,'Komal',10);
insert into Stu_Table values(2,'Ajay',10);
insert into Stu_Table values(3,'Rakesh',10);
insert into Stu_Table values(4,'Bhanu',10);
insert into Stu_Table values(2,'Ajay',10);
insert into Stu_Table values(3,'Rakesh',10);
insert into Stu_Table values(4,'Bhanu',10);
insert into Stu_Table values(5,'Santosh',10);
insert into Stu_Table values(1,'Komal',10);
insert into Stu_Table values(2,'Ajay',10);

Stu_Table

Records in the table:

+--------+----------+-----------+
| Stu_Id | Stu_Name | Stu_Class |
+--------+----------+-----------+
| 1      | Komal    | 10        |
| 2      | Ajay     | 10        |
| 3      | Rakesh   | 10        |
| 4      | Bhanu    | 10        |
| 5      | Santosh  | 10        |
| 6      | Tanuj    | 10        |
| 1      | Komal    | 10        |
| 2      | Ajay     | 10        |
| 3      | Rakesh   | 10        |
| 4      | Bhanu    | 10        |
| 5      | Santosh  | 10        |
| 2      | Ajay     | 10        |
| 3      | Rakesh   | 10        |
| 4      | Bhanu    | 10        |
| 5      | Santosh  | 10        |
| 1      | Komal    | 10        |
| 2      | Ajay     | 10        |
| 3      | Rakesh   | 10        |
| 4      | Bhanu    | 10        |
| 2      | Ajay     | 10        |
| 3      | Rakesh   | 10        |
| 4      | Bhanu    | 10        |
| 5      | Santosh  | 10        |
| 1      | Komal    | 10        |
| 2      | Ajay     | 10        |
+--------+----------+-----------+

Query

The given Query return you the records and retrieve a single value, by calculate from values in a column 'stu_name' enlisted in the select statement from 'Stu_Table'. The group by keyword group all  the records which is grouped by attribute 'stu_id' from a table 'Stu_Table'. 

select stu_name,count(stu_name) from stu_table group by stu_id;

Result

+----------+-----------------+
| stu_name | count(stu_name) |
+----------+-----------------+
| Komal    | 4               |
| Ajay     | 6               |
| Rakesh   | 5               |
| Bhanu    | 5               |
| Santosh  | 4               |
| Tanuj    | 1               |
+----------+-----------------+

                         

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