What does nvl mean in mysql

In MySQL, the NVL function is used to replace null values, and the syntax is: NVL(expression, replacement). It works according to the rules: if expression is not empty, it returns expression; if expression is empty, it returns replacement. In addition to the NVL functions, the ISNULL(), COALESCE(), and CASE statements are alternatives to null values.

NVL in MySQL

NVL (Null Value Logical) is a MySQL function used to replace null values (NULL). It works with the following syntax:

<code>NVL(expression, replacement)</code>

where:

• expression is the value to check
• replacement is The value to be returned if the value is empty

How it works

The NVL function works according to the following rules:

• If# If ##expression is not empty, expression is returned.
If
• expression is empty, replacement is returned.

Examples

<code>SELECT NVL(column_name, 'Default value') FROM table_name;

SELECT CASE WHEN column_name IS NULL THEN 'NULL' ELSE 'NOT NULL' END
FROM table_name;</code>

Usage

Fill in missing data in a query
• Handle null values ​​in an insert or update operation
• In Handling missing values ​​in data analysis

Alternative methods

ISNULL() function
• COALESCE() function
• CASE statement

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