How to use the notnull annotation

The usage is to limit the value range of the field by setting field constraints to avoid data errors or situations that do not comply with business rules. For more information on how to use the notnull annotation, you can read the following article.

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How to use the notnull annotation

Detailed explanation of usage of not null annotation

The usage is to limit the value range of fields by setting field constraints to avoid data errors or situations that do not comply with business rules.

Nov 07, 2023 am 11:00 AM

not null

How to delete not null restriction in mysql

In mysql, you can use the "ALTER TABLE" statement to delete the "not null" non-null restriction from the columns of the specified table. You can use modify to modify the data type and constraints of the fields in the table. The syntax is "ALTER TABLE table name MODIFY field name INT NULL;".

Apr 06, 2022 pm 03:25 PM

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Detailed explanation of NULL and NOT NULL in MySQL

This article introduces what NULL and NOT NULL are in MySQL, as well as the difference between NULL and NOT NULL, and some usage examples.

May 05, 2020 am 10:56 AM

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How to modify the not null attribute in mysql

MySQL is a very popular relational database management system that allows users to create, modify, and delete tables as well as query and operate data in tables. In MySQL, when we create a table, we can set a property for each column, such as data type, default value, primary key, foreign key, etc. Among them, a common attribute is NOT NULL, which means that the value of this column cannot be empty. In some cases, we may need to modify the NOT NULL attribute of a table. For example, when we create a table, we may not know

Apr 17, 2023 pm 04:40 PM