Mega Code Archive
Retrieve NULL value
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/*
mysql> select * from Student;
+-----------+------------+-----------+
| StudentID | first_name | last_name |
+-----------+------------+-----------+
| 1 | John | Jones |
| 2 | NULL | Burton |
| 3 | Emily | Scarlett |
| 4 | Bruce | Lee |
| 5 | Anna | Wolff |
| 6 | Vic | Andrews |
| 7 | NULL | Alaska |
+-----------+------------+-----------+
7 rows in set (0.01 sec)
mysql> select * from Student WHERE first_name IS NULL;
+-----------+------------+-----------+
| StudentID | first_name | last_name |
+-----------+------------+-----------+
| 2 | NULL | Burton |
| 7 | NULL | Alaska |
+-----------+------------+-----------+
2 rows in set (0.02 sec)
*/
Drop table Student;
CREATE TABLE Student (
StudentID INT NOT NULL PRIMARY KEY,
first_name VARCHAR(50),
last_name VARCHAR(50) NOT NULL
)TYPE = InnoDB;
INSERT INTO Student (StudentID,first_name, last_name) VALUES (4,'Bruce', 'Lee');
INSERT INTO Student (StudentID,first_name, last_name) VALUES (1,'John', 'Jones');
INSERT INTO Student (StudentID, last_name) VALUES (2, 'Burton');
INSERT INTO Student (StudentID, last_name) VALUES (7, 'Alaska');
INSERT INTO Student (StudentID,first_name, last_name) VALUES (5,'Anna', 'Wolff');
INSERT INTO Student (StudentID,first_name, last_name) VALUES (6,'Vic', 'Andrews');
INSERT INTO Student (StudentID,first_name, last_name) VALUES (3,'Emily', 'Scarlett');
select * from Student;
select * from Student WHERE first_name IS NULL;
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