MYSQL have set a column to not null but still it's accepting null value [duplicate]

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Structure for a table in mysql5.5

tablename:

id:
name:
detail:

here even altering the table:

ALTER TABLE tablename MODIFY name VARCHAR(255) CHARACTER SET utf8 COLLATE utf8_persian_ci NOT NULL;

OR 

ALTER TABLE `tablename` CHANGE `name` `name` VARCHAR(255) CHARACTER SET utf8 COLLATE utf8_persian_ci NOT NULL DEFAULT NOT NULL;

after inserting value:

INSERT INTO `databasename`.`tablename` (`id`, `name`, `detail`) VALUES (NULL, '', 'asdfasfdadsfadsfafd');

query has run successfully no error row has been added to table,

how can i prevent such empty or null.

regards

SAR

출처 mysql sql

1 답변

0

Try this:

ALTER TABLE tablename 
MODIFY COLUMN name VARCHAR(255) CHARACTER SET utf8 COLLATE utf8_persian_ci NOT NULL CHECK (name <> '');

DEMO:

mysql> create table tablename(id int(2) not null, something varchar(25) null, primary key(id));
Query OK, 0 rows affected (0.15 sec)
mysql> insert into tablename values(0,'hello');
Query OK, 1 row affected (0.38 sec)

mysql> insert into tablename values(1,'salut');
Query OK, 1 row affected (0.31 sec)

mysql> select * from tablename;
+----+-----------+
| id | something |
+----+-----------+
|  0 | hello     |
|  1 | salut     |
+----+-----------+
2 rows in set (0.00 sec)

Now, I run the UPDATE command:

mysql> ALTER TABLE tablename  MODIFY COLUMN something VARCHAR(255) CHARACTER SET utf8 COLLATE utf8_persian_ci NOT NULL;
Query OK, 2 rows affected (0.70 sec)
Records: 2  Duplicates: 0  Warnings: 0

I insert a normal row:

mysql> insert into tablename values(2,'france');
Query OK, 1 row affected (0.29 sec)

But it does not allow me to insert a NULL value:

mysql> insert into tablename values(3,NULL);
ERROR 1048 (23000): Column 'something' cannot be null

I check to be sure:

mysql> select * from tablename;
+----+-----------+
| id | something |
+----+-----------+
|  0 | hello     |
|  1 | salut     |
|  2 | france    |
+----+-----------+
3 rows in set (0.00 sec)

  • No effect Same result. - SAR
  • @abas_rafiq I tried the command I gave you on a test table I created. You can see it does its job very well (it can not allow me NULL values insertion). But in your case, I do not understand why. I suggest you to show your MySQL version - user3522371
  • please try (insert into tablename values(3,'');) - SAR
  • @abas_rafiq NO, you are wrong: '' is different from NULL because '' means empty string so it will accept it of course - user3522371
  • yes on my insert i have explain not null i mean not empty. - SAR

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