# How to Use CARDINALITY() Function in PostgreSQL?

> In PostgreSQL, CARDINALITY() is an array function that counts the total number of array elements. The return type of the stated function is INT.

In PostgreSQL, a variety of array functions are available that assist us in working with the array data productively. Some frequently used array functions include the ARRAY_APPEND(), ARRAY_REMOVE(), ARRAY_REPLACE(), etc. In Postgres, **CARDINALITY()** is also a notable array function that counts the total number of array elements.

This article will demonstrate different use cases of the CARDINALITY() function using appropriate examples.

 **How to Use CARDINALITY() Function in PostgreSQL?**

The CARDINALITY() function accepts a single or multi-dimensional array and retrieves the total number of elements present in that array. Here is the syntax for the CARDINALITY() function:
    
    
    CARDINALITY(arr);

It retrieves an integer that represents the number of the array elements.

Let’s learn it practically.

 **Example 1: CARDINALITY() Function With 1-D Array**

In the following example, a single dimensional array is passed to the “CARDINALITY()” function:
    
    
    SELECT CARDINALITY(ARRAY['Joe', 'John', 'Mike', 'Seth']);

The output demonstrates that the input array has four elements.

 **Example 2: CARDINALITY() Function With Multi-Dimensional Array**

Let’s learn how to find the array elements of the multi-dimensional array using the CARDINALITY() function:
    
    
    SELECT CARDINALITY('[2:4][2:3]={{10,20},{70,90},{100,120}}'::INTEGER[]);

The output shows that the given multi-dimensional array has six elements.

 **Example 3: CARDINALITY() Function on Table’s Data**

In this example, we will use an already created table named “std_info”:
    
    
    SELECT * FROM std_info;

Let’s utilize the CARDINALITY() function on the “std_num” column of the “std_info” table:
    
    
    SELECT std_name, std_num, CARDINALITY(std_num) 
    FROM std_info;

The CARDINALITY() function retrieves the total elements of the std_num array.

That’s all from this Postgres guide.

 **Conclusion**

In PostgreSQL, **CARDINALITY()** is an array function that counts the total number of array elements. It accepts a single or multi-dimensional array and retrieves the total number of elements present in that array. The return type of the stated function is INT. This post explained a complete guide on how to use the CARDINALITY() function in PostgreSQL.

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