Select: - Select is used to fetch the data from the tables in the database. Following is the syntax for using the select statement.
Syntax: -
SELECT <Column Name> FROM <Table Name>
;
Example: - If you want to see Teacher Name from the Teacher Table:-
Select Teacher_Name from Teacher;
The above query will fetch the names of all the teachers in the teacher table.
To fetch all the details of the teachers we will use the following query: -
Select * from Teacher;
The above query will display all the details of the teachers. Here '*' refers to all the columns.
To fetch the details of more than one column (not all the columns), we will use delimeter (,) between the column names. For example: -
Select Teacher_Name, Qualification from Teacher; will display the Teacher Names and their qualifications.
Where Clause: - Where clause is used to fetch the data according according to the conditions given by the user with the help of operators. The following is the syntax for using where: -
Syntax: - SELECT <Column Name> FROM
<Table Name> WHERE <Condition>
Example: - If you want to see the ID of the students who secured percentage of marks equal to 65%.
Select Student_ID from Marks where MarksPercentage = 65;
Similarly we can use the different operators with where clause: -
Select Student_ID from Marks where MarksPercentage > 65;
Select Student_ID from Marks where MarksPercentage < 65;
Select Student_ID from Marks where MarksPercentage < > 65;
Order By: - It is used to fetch the data in the given order (Ascending or Descending). The following is the syntax for order by: -
Syntax: - SELECT <column Name> FROM <Table Name> [WHERE ] ORDER BY [ASC, DESC] Example: - If you want to see the details of the students in ascending order according to the name.
Select * from Student order by StudentName;
In the above example we have not mentioned the type of the ordering because by default it is ascending order but for the descending order we have to specify the order: -
Select * from Student order by StudentName Desc; will display the data in the descending order. |