T-SQL - WHERE Clause
The MS SQL Server WHERE clause is used to specify a condition while fetching the data from single table or joining with multiple tables.
If the given condition is satisfied, only then it returns a specific value from the table. You will have to use WHERE clause to filter the records and fetch only necessary records.
The WHERE clause is not only used in SELECT statement, but it is also used in UPDATE, DELETE statement, etc., which we would examine in subsequent chapters.
Syntax
Following is the basic syntax of SELECT statement with WHERE clause −
SELECT column1, column2, columnN
FROM table_name
WHERE [condition]
You can specify a condition using comparison or logical operators like >, <, =, LIKE, NOT, etc. The following example will make this concept clear.
Example
Consider the CUSTOMERS table having the following records −
ID NAME AGE ADDRESS SALARY
1 Ramesh 32 Ahmedabad 2000.00
2 Khilan 25 Delhi 1500.00
3 kaushik 23 Kota 2000.00
4 Chaitali 25 Mumbai 6500.00
5 Hardik 27 Bhopal 8500.00
6 Komal 22 MP 4500.00
7 Muffy 24 Indore 10000.00
Following command is an example which would fetch ID, Name and Salary fields from the CUSTOMERS table where salary is greater than 2000.
SELECT ID, NAME, SALARY
FROM CUSTOMERS
WHERE SALARY > 2000;
The above command will produce the following output.
ID NAME SALARY
4 Chaitali 6500.00
5 Hardik 8500.00
6 Komal 4500.00
7 Muffy 10000.00
Following command is an example, which would fetch ID, Name and Salary fields from the CUSTOMERS table for a customer with the name ‘Hardik’. It is important to note that all the strings should be given inside single quotes ('') whereas numeric values should be given without any quote as in the above example −
SELECT ID, NAME, SALARY
FROM CUSTOMERS
WHERE NAME = 'Hardik';
The above command will produce the following output.
ID NAME SALARY
5 Hardik 8500.00
