WHERE Clause-To limit the retrieval of the data from the database for given condition

WHERE Clause
Where clause is used to limit the retrieval of the data from the database for given condition 
and use the key word WHERE.Where clause follows the FROM clause in the SQL Statement.

Syntax-

SELECT   *|[DISTINCT]Column|expression [Alias]
From Table_Name;
[WHERE <Condition(s)>]

SELECT -a list of columns
* -Select the all columns 
DISTINCT-suppresses the duplicates 
alias-alternate name of the column(s) that is/are used as the heading of that column(s).  
Table_name-specifies the table name containing the column(s). 
WHERE<Condition(s)>- the condition must meet to retrieve the data from the database.

Note- Condition is combination of column names,constants,variables,expressions and comparison operator.

Example- 

1.Write the query to find the id,name,address of employee whose address is Lucknow.

Query-    select ID,Name,Address from employee where address='Lucknow';
Output-
Number of Records: 2
ID   Name  address
4    Aman  Lucknow
5    Hari  Lucknow

2.Write the query to retrieve employees details whose salary is more than 10000 and less than 50000. 

Query-  SELECT * FROM employee where salary>10000 and salary<50000
Output-
Number of Records: 1
ID  Name      email             address  phone_number   salary
5   Hari   Hari@gmail.com        Lucknow   36756890      15000

3.Write the query to display the id,name and the yearly salary of the employees whose annual salaries are less than 200000.

Query-SELECT ID , Name , salary*12  Annual_salary FROM employee where Annual_salary<200000;
Output-
Number of Records: 2
ID Name     Annual_salary
1 sharat    60000
5 Hari      180000

4.Write the query to display the id,name and the yearly salary of the employees and also label the column heading id as Emp_Id,name as Employee Name and salary as 
Yearly Salary Package.

Query-  SELECT ID as Emp_Id, Name as "Employee Name", salary*12 as "Yearly Salary Package" FROM employee;
Output-
Number of Records: 5
Emp_Id Employee Name     Yearly Salary Package
1         sharat         60000
2         Ajay           612000
3         Amit           612000
4         Aman           612000
5         Hari           180000