How to set null in mysql

Methods to set NULL in MySQL include: 1. Use the INSERT statement to insert a NULL value; 2. Use the UPDATE statement to update the value to NULL; 3. Use the ALTER TABLE statement to set the column to allow NULL; 4. Use DEFAULT The NULL keyword sets the column's default value to NULL when creating a new table. Note that NULL, unlike the empty string or zero, is always false when compared, and should be used with caution to avoid data integrity issues.

How to set NULL in MySQL

NULL represents an unknown or non-existent value in MySQL. The method of setting NULL is as follows:

1. Use the INSERT statement

<code class="sql">INSERT INTO table_name (column_name) VALUES (NULL);</code>

2. Use the UPDATE statement

<code class="sql">UPDATE table_name SET column_name = NULL WHERE condition;</code>

3. Use the ALTER TABLE statement

To set the column to allow NULL, you can use the ALTER TABLE statement, as follows:

<code class="sql">ALTER TABLE table_name ALTER COLUMN column_name SET NULL;</code>

4. When using the DEFAULT keyword

to create a new table, you can use the DEFAULT NULL keyword to set the default value of the column to NULL, as follows:

<code class="sql">CREATE TABLE table_name (column_name VARCHAR(255) DEFAULT NULL);</code>

Note:

• NULL is not the same as the empty string or zero.
• NULL The value is always false when compared.
• Avoid using NULL in columns involving mathematical operations as it may cause unexpected results.
• Use NULL wisely as it may introduce data integrity issues.

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