Filtering Data From Tables in MySQL LIMIT, IS NULL, and IS NOT NULL Operators

You may want results with no NULL values across numerous columns in some circumstances.

We’ll look at how to use the IS NOT NULL operator to filter entries without nulls in an MS SQL Server database table column.

For demonstration purposes, we will create a demo orders table in a database called “geeks.”

• Making a Database:

Create a geek database using an SQL query.

Create a database

• Making Use of the Database:

To change the database context to geeks, use the SQL command below:

USE geeks;

• Table Definition

 In our geek’s database, we make a table.

Simply said, NULL is a placeholder for data that does not exist. When inserting data into tables, there can be moments when some field values are unavailable.

In MySQL, NULL is employed as a placeholder for values that have not been entered in order to fulfill the standards of real relational database management systems.

Let’s go through some of the fundamentals of NULL.

1. NULL is not a data type, it is not recognized as an “int,” “date,” or any other specified data type.
2. Arithmetic operations using NULL always return NULL, as in 69 + NULL = NULL.
3. All aggregate functions have no effect on rows with NULL values.

Why is null not used?

There will be times when we must compute a query result set and provide the results. Any arithmetic operation performed on columns with a NULL value yields a null output. To prevent such circumstances from occurring, we may utilize the NOT NULL clause to limit the outcomes on which our data acts.

Values that are not NULL

Assume we want to establish a table with particular fields that should always be filled in when adding new rows into a table. When constructing the table, we may utilize the NOT NULL clause on a specific field.

• The term that conducts the Boolean comparison is “is null.” If the provided value is NULL, it returns true; otherwise, it returns false.
• The term that conducts the Boolean comparison is “NOT NULL.” If the given value is not NULL, it returns true; otherwise, it returns false.

Contrasting null values

• Three-value logic entails conducting Boolean operations on situations involving NULL and returning “Unknown,” “True,” or “False.”
• When doing comparison operations using NULL, for example, using the “IS NULL” keyword can yield either true or false. Other comparison operators provide “Unknown” (NULL).