MySQL NULL Functions

MySQL provides several functions that are specifically designed to work with NULL values. These functions allow you to check for NULL values, handle NULL values, and perform operations on NULL values.

Here are some of the commonly used NULL functions in MySQL:

IS NULL:

This function checks if a value is NULL. It returns 1 if the value is NULL, otherwise it returns 0. For example:

SELECT * FROM table_name WHERE column_name IS NULL;

This query will return all rows in the table_name where the value of column_name is NULL.

IS NOT NULL:

This function checks if a value is not NULL. It returns 1 if the value is not NULL, otherwise it returns 0. For example:

SELECT * FROM table_name WHERE column_name IS NOT NULL;

This query will return all rows in the table_name where the value of column_name is not NULL.

IFNULL:

This function returns the first argument if it is not NULL, otherwise it returns the second argument. For example:

SELECT IFNULL(column_name, 'NA') FROM table_name;

This query will return the value of column_name if it is not NULL, otherwise it will return the string ‘NA’.

COALESCE:

This function returns the first non-NULL value in a list of arguments. For example:

SELECT COALESCE(column_name1, column_name2, column_name3, 'NA') FROM table_name;

This query will return the first non-NULL value among column_name1, column_name2, and column_name3, or the string ‘NA’ if all of these columns are NULL.

NULLIF:

This function returns NULL if the two arguments are equal, otherwise it returns the first argument. For example:

SELECT NULLIF(column_name, 0) FROM table_name;

This query will return NULL if the value of column_name is 0, otherwise it will return the value of column_name.

These functions are useful when dealing with NULL values in your MySQL queries, and can help you handle these values in a more efficient and concise way.

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