Explain What Is "IS NULL" Query in MySQL

The ‘IS NULL” query in the MySQL database shows the data which is either missing or is unknown to DMS. A NULL value is different as it has no value, it is neither equal to zero integer or to an empty set.  Null is a state, not a value, if we compare the NULL value to any other NULL value, the result will always be NULL because it’s unknown itself. A “IS NULL” query is used when data is missing or unknown for example we make a list of phone directories, if any person’s phone number is unknown then “IS NULL” will extract it and the number can later be added to complete the directory.

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Explain What Is "IS NULL" Query in MySQL

The ‘IS NULL” query in the MySQL database shows the data which is either missing or is unknown to DMS. A NULL value is different as it has no value, it is neither equal to zero integer or to an empty set.  Null is a state, not a value, if we compare the NULL value to any other NULL value, the result will always be NULL because it’s unknown itself. A “IS NULL” query is used when data is missing or unknown for example we make a list of phone directories, if any person’s phone number is unknown then “IS NULL” will extract it and the number can later be added to complete the directory.

#mysql 

Learn About MySQL IS NULL With EXAMPLES

Learn About MySQL IS NULL with EXAMPLES

In our previous tutorial – you have learned about logical operators like AND, OR, NOT and MySQL IS NOT NULL with syntax and examples. IF you want to know more about MySQL logical operators and IS NOT NUL.

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How To Check Variable Is NULL in PHP | PHP is_null() Tutorial Example

How To Check Variable Is NULL in PHP | PHP is_null() Tutorial Example is today’s topic. PHP is_null() function finds whether a variable is NULL. A special NULL value represents the variable with no value. The NULL is the only possible value of type NULL.

The variable is considered to be null if:

1. It has been assigned a constant NULL.
2. It has not been set to any value yet.
3. It has been unset().

How To Check Variable Is NULL in PHP

The is_null() function is used to test whether the variable is NULL or not. The is_null() function returns TRUE if the variable is null, FALSE otherwise.

There is only one value of type  null, and it is the case-insensitive constant NULL.

#php #false #null

What is null value in SQL?

In SQL, null is a special marker that represents the absence of a value in a column of a table. It is not the same as an empty string or a zero value, but rather indicates that the value is unknown or undefined. Null values can be tricky to work with because they can produce unexpected results in SQL queries and calculations. As such, it's important to handle null values carefully and explicitly account for them in your SQL code. See more DBMS interview questions.

What is Null Safety in Kotlin?

Kotlin is null safety that is, it eliminates the jeopardy of null reference from the code. Null Pointer Exceptions are thrown by the program at runtime and sometimes cause application failure or system crashes. In Kotlin, the type system differentiates between references that can hold null (nullable references) and those that cannot (non-null references).

var c: String = "abc"

c = null // Null exception error cause the String cannot hold null.

you can add "?" to the type to decalre a nullable variable

var c: String? = "abc"

c= null // ok