Toán tử KHÔNG PHẢI của SQL

SQL NOT là một toán tử Boolean được sử dụng với mệnh đề WHERE. Toán tử NOT hiển thị các bản ghi nếu biểu thức là sai. Khi chúng tôi sử dụng toán tử NOT, chúng tôi chỉ tìm nạp những dữ liệu từ Bảng không đáp ứng tiêu chí trong biểu thức đã cho.

Chúng ta có thể sử dụng toán tử NOT với câu lệnh SELECT, câu lệnh UPDATE và câu lệnh DELETE. Chúng ta có thể sử dụng toán tử NOT với các toán tử khác như toán tử AND, toán tử HOẶC, toán tử GIỮA, toán tử IN, toán tử LIKE và các toán tử khác.

Cú pháp của toán tử NOT:

SELECT Column_name1, Column_name2, Column_name3 FROM Table_name WHERE Column_name NOT expression;

Bảng hiển thị kết quả của toán tử NOT:

	KHÔNG
Đúng	Sai
Sai	Đúng
Không	Null

Hãy hiểu khái niệm toán tử NOT trong SQL với sự trợ giúp của các ví dụ.

Hãy xem xét các bảng hiện có, có các bản ghi sau:

Bảng 1:Nhân viên

NGƯỜI LAO ĐỘNG	FIRST_NAME	LAST_NAME	TIỀN LƯƠNG	THÀNH PHỐ	CỤC	MANAGERID
1001	VAIBHAVI	MISHRA	65500	PUNE	ORACLE	1
1002	VAIBHAV	SHARMA	60000	NOIDA	C #	5
1003	NIKHIL	VANI	50500	JAIPUR	FMW	2
2001	PRACHI	SHARMA	55500	CHANDIGARH	ORACLE	1
2002	BHAVESH	JAIN	65500	PUNE	FMW	2
2003	RUCHIKA	JAIN	50000	MUMBAI	C #	5
3001	PRANOTI	CHIA SẺ	55500	PUNE	JAVA	3
3002	ANUJA	DÂY	50500	JAIPUR	FMW	2
3003	DEEPAM	JAUHARI	58500	MUMBAI	JAVA	3
4001	RAJESH	MỤC TIÊU	60500	MUMBAI	KIỂM TRA	4
4002	ASHWINI	BAGHAT	54500	NOIDA	JAVA	3
4003	RUCHIKA	AGARWAL	60000	DELHI	ORACLE	1
5001	ARCHIT	SHARMA	55500	DELHI	KIỂM TRA	4
5002	SANKET	CHAUHAN	70000	HYDERABAD	JAVA	3
5003	ROSHAN	NEHTE	48500	CHANDIGARH	C #	5
6001	RAHUL	NIKAM	54500	BANGALORE	KIỂM TRA	4
6002	CHÚ Ý	JADHAV	60500	BANGALORE	C #	5
6003	NIKITA	INGALE	65000	HYDERABAD	ORACLE	1

Bảng 2:Người quản lý

managerid	manager_name	manager_department
1	Snehdeep Kaur	ORACLE
2	KirtiKirtane	FMW
3	Abhishek Manish	JAVA
4	AnupamMishra	TESTING
5	Akash Kadam	C#

Ví dụ 1: Write a query to display the employees' details where the city is NOT Pune.

SELECT * FROM EMPLOYEES WHERE NOT CITY = 'PUNE';

We display employees' details where the city should not be 'Pune'. We used the NOT operator followed by the city column in the WHERE clause. The NOT operator means only those employee details to be displayed whose city is not Pune.

The output of the above query:

EMPLOYEEID	FIRST_NAME	LAST_NAME	SALARY	CITY	DEPARTMENT	MANAGERID
1002	VAIBHAV	SHARMA	60000	NOIDA	C#	5
1003	NIKHIL	VANI	50500	JAIPUR	FMW	2
2001	PRACHI	SHARMA	55500	CHANDIGARH	ORACLE	1
2003	RUCHIKA	JAIN	50000	MUMBAI	C#	5
3002	ANUJA	WANRE	50500	JAIPUR	FMW	2
3003	DEEPAM	JAUHARI	58500	MUMBAI	JAVA	3
4001	RAJESH	GOUD	60500	MUMBAI	TESTING	4
4002	ASHWINI	BAGHAT	54500	NOIDA	JAVA	3
4003	RUCHIKA	AGARWAL	60000	DELHI	ORACLE	1
5001	ARCHIT	SHARMA	55500	DELHI	TESTING	4
5002	SANKET	CHAUHAN	70000	HYDERABAD	JAVA	3
5003	ROSHAN	NEHTE	48500	CHANDIGARH	C#	5
6001	RAHUL	NIKAM	54500	BANGALORE	TESTING	4
6002	ATISH	JADHAV	60500	BANGALORE	C#	5
6003	NIKITA	INGALE	65000	HYDERABAD	ORACLE	1

As we can see, only those records are displayed where the city is not Pune.

Ví dụ 2: Write a query to display the employees’ details where the Department is NOT C#.

SELECT * FROM EMPLOYEES WHERE NOT DEPARTMENT = 'C#';

From the above query, we display employees' details where Department should not be 'C#'. Only those employee details to be displayed whose Department is not C#. We used the NOT operator followed by the city column in the WHERE clause.

The output of the above query:

EMPLOYEEID	FIRST_NAME	LAST_NAME	SALARY	CITY	DEPARTMENT	MANAGERID
1001	VAIBHAVI	MISHRA	65500	PUNE	ORACLE	1
1003	NIKHIL	VANI	50500	JAIPUR	FMW	2
2001	PRACHI	SHARMA	55500	CHANDIGARH	ORACLE	1
2002	BHAVESH	JAIN	65500	PUNE	FMW	2
3001	PRANOTI	SHENDE	55500	PUNE	JAVA	3
3002	ANUJA	WANRE	50500	JAIPUR	FMW	2
3003	DEEPAM	JAUHARI	58500	MUMBAI	JAVA	3
4001	RAJESH	GOUD	60500	MUMBAI	TESTING	4
4002	ASHWINI	BAGHAT	54500	NOIDA	JAVA	3
4003	RUCHIKA	AGARWAL	60000	DELHI	ORACLE	1
5001	ARCHIT	SHARMA	55500	DELHI	TESTING	4
5002	SANKET	CHAUHAN	70000	HYDERABAD	JAVA	3
6001	RAHUL	NIKAM	54500	BANGALORE	TESTING	4
6003	NIKITA	INGALE	65000	HYDERABAD	ORACLE	1

As we can see, only those records are displayed where Department is not C#.

Example 3: Write a query to display employee details where the city is not ‘Mumbai’, 'Pune', and ‘Delhi’.

SELECT * FROM EMPLOYEES WHERE CITY NOT IN ('PUNE', 'MUMBAI', 'DELHI');

From the above query, we display the employees' details where city is not 'Pune', 'Mumbai', and 'Delhi'. We have used IN operator with the NOT operator. NOT IN operator allow only those records whose values are not present in the IN operator parameter.

The output of the above query:

EMPLOYEEID	FIRST_NAME	LAST_NAME	SALARY	CITY	DEPARTMENT	MANAGERID
1002	VAIBHAV	SHARMA	60000	NOIDA	C#	5
1003	NIKHIL	VANI	50500	JAIPUR	FMW	2
2001	PRACHI	SHARMA	55500	CHANDIGARH	ORACLE	1
3002	ANUJA	WANRE	50500	JAIPUR	FMW	2
4002	ASHWINI	BAGHAT	54500	NOIDA	JAVA	3
5002	SANKET	CHAUHAN	70000	HYDERABAD	JAVA	3
5003	ROSHAN	NEHTE	48500	CHANDIGARH	C#	5
6001	RAHUL	NIKAM	54500	BANGALORE	TESTING	4
6002	ATISH	JADHAV	60500	BANGALORE	C#	5
6003	NIKITA	INGALE	65000	HYDERABAD	ORACLE	1

As we can see, only those records are displayed where city is not 'Pune', 'Mumbai', and 'Delhi.'

Ví dụ 4: Write a query to display employee details where the city is not ‘Mumbai’ or Department is not ‘Oracle’.

SELECT * FROM EMPLOYEES WHERE NOT CITY = 'MUMBAI' AND NOT DEPARTMENT = 'ORACLE';

From the above query, we have displayed the employees' details where the city is not 'Mumbai' or Department is not 'Oracle'. The above query excludes all those records whose city is 'Mumbai' and Department is 'Oracle’.

The output of the above query:

EMPLOYEEID	FIRST_NAME	LAST_NAME	SALARY	CITY	DEPARTMENT	MANAGERID
1002	VAIBHAV	SHARMA	60000	NOIDA	C#	5
1003	NIKHIL	VANI	50500	JAIPUR	FMW	2
2002	BHAVESH	JAIN	65500	PUNE	FMW	2
3001	PRANOTI	SHENDE	55500	PUNE	JAVA	3
3002	ANUJA	WANRE	50500	JAIPUR	FMW	2
4002	ASHWINI	BAGHAT	54500	NOIDA	JAVA	3
5001	ARCHIT	SHARMA	55500	DELHI	TESTING	4
5002	SANKET	CHAUHAN	70000	HYDERABAD	JAVA	3
5003	ROSHAN	NEHTE	48500	CHANDIGARH	C#	5
6001	RAHUL	NIKAM	54500	BANGALORE	TESTING	4
6002	ATISH	JADHAV	60500	BANGALORE	C#	5

As we can see, only those records are displayed where the city is not 'Mumbai' and Department is not 'Oracle'.

Example 5: Write a query to display employee details where the salary is not greater than 60000.

SELECT * FROM EMPLOYEES WHERE NOT SALARY > 60000;

From the above query, we displayed the employees' details where salary is not greater than 60000. Here, we didn't use less than the operator. We used NOT operator with greater than the operator.

The output of the above query:

EMPLOYEEID	FIRST_NAME	LAST_NAME	SALARY	CITY	DEPARTMENT	MANAGERID
1002	VAIBHAV	SHARMA	60000	NOIDA	C#	5
1003	NIKHIL	VANI	50500	JAIPUR	FMW	2
2001	PRACHI	SHARMA	55500	CHANDIGARH	ORACLE	1
2003	RUCHIKA	JAIN	50000	MUMBAI	C#	5
3001	PRANOTI	SHENDE	55500	PUNE	JAVA	3
3002	ANUJA	WANRE	50500	JAIPUR	FMW	2
3003	DEEPAM	JAUHARI	58500	MUMBAI	JAVA	3
4002	ASHWINI	BAGHAT	54500	NOIDA	JAVA	3
4003	RUCHIKA	AGARWAL	60000	DELHI	ORACLE	1
5001	ARCHIT	SHARMA	55500	DELHI	TESTING	4
5003	ROSHAN	NEHTE	48500	CHANDIGARH	C#	5
6001	RAHUL	NIKAM	54500	BANGALORE	TESTING	4

As we can see, only those records are displayed where the salary is not greater than 60000.

Example 6: Write a query to display employees' details where the city is not Bangalore and Department is not FMW or Testing.

SELECT * FROM EMPLOYEES WHERE NOT CITY = 'BANGALORE' AND NOT (DEPARTMENT = 'FMW' OR DEPARTMENT = 'TESTING');

From the above query, we displayed the employees' details where the city is not Bangalore, and neither Department is FMW or Testing. Explanation of the above query how actually query works, first the bracket part will get executed i.e.

Step1: (DEPARTMENT =‘FMW’ OR DEPARTMENT =‘TESTING’); the output of this query part is that only employee's details whose Department are either FMW or Testing are selected.

Step 2: WHERE NOT CITY =‘BANGALORE’AND NOT (output of the query); the output of this query part will terminate all those employees' details where the city is Bangalore and output of step 1.

Step 3: SELECT * FROM EMPLOYEES; the output of this final query is the records that are left from excluding the records from the above query part.

The output of the above query:

EMPLOYEEID	FIRST_NAME	LAST_NAME	SALARY	CITY	DEPARTMENT	MANAGERID
1001	VAIBHAVI	MISHRA	65500	PUNE	ORACLE	1
1002	VAIBHAV	SHARMA	60000	NOIDA	C#	5
2001	PRACHI	SHARMA	55500	CHANDIGARH	ORACLE	1
2003	RUCHIKA	JAIN	50000	MUMBAI	C#	5
3001	PRANOTI	SHENDE	55500	PUNE	JAVA	3
3003	DEEPAM	JAUHARI	58500	MUMBAI	JAVA	3
4002	ASHWINI	BAGHAT	54500	NOIDA	JAVA	3
4003	RUCHIKA	AGARWAL	60000	DELHI	ORACLE	1
5002	SANKET	CHAUHAN	70000	HYDERABAD	JAVA	3
5003	ROSHAN	NEHTE	48500	CHANDIGARH	C#	5
6003	NIKITA	INGALE	65000	HYDERABAD	ORACLE	1

As we can see from the output, only those records are displayed where the city is not 'Bangalore' and Department is not 'FMW', or Department is not 'Testing'.

Example 7: Write a subquery to display employees' details where the manager id is not 2 from the manager table.

SELECT * FROM EMPLOYEES WHERE NOT MANAGERID = (SELECT MANAGERID FROM MANAGER WHERE MANAGERID = 2);

We display the employees' details from the above query where the manager id is not 2. We have used a subquery in the above query.

Explanation of the above query how the actual query works:

Bước 1: (SELECT MANAGERID FROM MANAGER WHERE MANAGERID =2);

First, the inner query will get executed. The output of this query is only manager details selected where manager id =2. The output of the query:

Step 2: SELECT * FROM EMPLOYEES WHERE NOT MANAGERID =2;

2 is the output of the inner query, which will now use as input for the main query to display the final output of the entire query. The output of the above query will be those employees' details where the manager id is not 2 in the employees' Table.

The output of the above query:

EMPLOYEEID	FIRST_NAME	LAST_NAME	SALARY	CITY	DEPARTMENT	MANAGERID
1001	VAIBHAVI	MISHRA	65500	PUNE	ORACLE	1
1002	VAIBHAV	SHARMA	60000	NOIDA	C#	5
2001	PRACHI	SHARMA	55500	CHANDIGARH	ORACLE	1
2003	RUCHIKA	JAIN	50000	MUMBAI	C#	5
3001	PRANOTI	SHENDE	55500	PUNE	JAVA	3
3003	DEEPAM	JAUHARI	58500	MUMBAI	JAVA	3
4001	RAJESH	GOUD	60500	MUMBAI	TESTING	4
4002	ASHWINI	BAGHAT	54500	NOIDA	JAVA	3
4003	RUCHIKA	AGARWAL	60000	DELHI	ORACLE	1
5001	ARCHIT	SHARMA	55500	DELHI	TESTING	4
5002	SANKET	CHAUHAN	70000	HYDERABAD	JAVA	3
5003	ROSHAN	NEHTE	48500	CHANDIGARH	C#	5
6001	RAHUL	NIKAM	54500	BANGALORE	TESTING	4
6002	ATISH	JADHAV	60500	BANGALORE	C#	5
6003	NIKITA	INGALE	65000	HYDERABAD	ORACLE	1

As we can see in the output, only those records are displayed where the manager id is not 2.

Example 8: Write a query to display employee id, first name and last name, the city from the employees' Table, and manager id from the manager table where the city is not 'Hyderabad'.

SELECT E.EMPLOYEEID, CONCAT (E.FIRST_NAME, CONCAT (" ", E.LAST_NAME)) AS NAME, E.CITY, M.MANAGERID FROM EMPLOYEES E INNER JOIN MANAGER M ON E.MANAGERID = M.MANAGERID WHERE NOT E.CITY = 'HYDERABAD';

We join two tables from the above query and display the employees' details where the city is not 'Hyderabad'. We also did concatenation for First Name and Last Name as Name. And records are displayed in ascending order.

The output of the above query:

EMPLOYEEID	NAME	CITY	MANAGERID
1001	VAIBHAVI MISHRA	PUNE	1
2001	PRACHI SHARMA	CHANDIGARH	1
4003	RUCHIKA AGARWAL	DELHI	1
1003	NIKHIL VANI	JAIPUR	2
2002	BHAVESH JAIN	PUNE	2
3002	ANUJA WANRE	JAIPUR	2
3001	PRANOTI SHENDE	PUNE	3
3003	DEEPAM JAUHARI	MUMBAI	3
4002	ASHWINI BAGHAT	NOIDA	3
4001	RAJESH GOUD	MUMBAI	4
5001	ARCHIT SHARMA	DELHI	4
6001	RAHUL NIKAM	BANGALORE	4
1002	VAIBHAV SHARMA	NOIDA	5
2003	RUCHIKA JAIN	MUMBAI	5
3003	ROSHAN NEHTE	CHANDIGARH	5
6002	ATISH JADHAV	BANGALORE	5

As we can see in the output, only those records are displayed where the city is not 'Hyderabad'.

Example 9: Write a query to display employees’ details where salary is not between 50000 and 60000.

SELECT * FROM EMPLOYEES WHERE SALARY IS NOT BETWEEN 50000 AND 60000;

The above query displays employees' details where employee salary is not between 50000 and 60000. We used BETWEEN operator with NOT operator to select salary between 50000 and 60000.

The output of the above query:

EMPLOYEEID	FIRST_NAME	LAST_NAME	SALARY	CITY	DEPARTMENT	MANAGERID
1001	VAIBHAVI	MISHRA	65500	PUNE	ORACLE	1
2002	BHAVESH	JAIN	65500	PUNE	FMW	2
4001	RAJESH	GOUD	60500	MUMBAI	TESTING	4
5002	SANKET	CHAUHAN	70000	HYDERABAD	JAVA	3
5003	ROSHAN	NEHTE	48500	CHANDIGARH	C#	5
6002	ATISH	JADHAV	60500	BANGALORE	C#	5
6003	NIKITA	INGALE	65000	HYDERABAD	ORACLE	1

As we can see in the output, only those records are displayed where the salary is not between 50000 and 60000.