PostgreSQL Array Functions: Syntax & Essential Operations

on Database Management Systems, PostgreSQL • July 13th, 2022 • Write for Hevo

PostgreSQL Array Functions- Featured Image

Are you struggling with inserting multiple values in the same columns in your PostgreSQL database? Creating numerous columns in your database, for example, to store your users’ primary and secondary phone numbers, is still bothering you?

Then, in this case, PostgreSQL Array Functions can rescue you from the hassle of complications.

If you want a basic understanding, you came on the correct hyperlink to start with PostgreSQL Array Functions. This blog will provide information on some of the widely used PostgreSQL Array functions, Syntax, along with Examples.

Table of Contents

What is Array Function in PostgreSQL?

PostgreSQL Array
Image Source

In PostgreSQL, array functions are helpful to store either single or multiple values in columns. This PostgreSQL feature allows users to convert any column into an array, including built-in user-defined and enumerated data types.

A table’s columns can be specified as variable-length multidimensional arrays in PostgreSQL. Every PostgreSQL data type has a corresponding array type.

The integer data type, for example, has the integer[] array type, whereas the character data type has the character[] array type, and so on. The same applies to user-defined data types as well. When a user declares a data type, PostgreSQL creates the associated array type in the background.

Why Use Array Function in PostgreSQL?

PostgreSQL Array Functions have a variety of reasons to be used. Some of them are mentioned below:

  • The array index allows users to access the items quickly.
  • PostgreSQL includes a number of functions for working with arrays. For example array_append(), array_cat(), and array_dims().
  • You can insert, update or delete an array entry using an index.
  • Inserting array elements is simple since we may use several syntaxes such as the [] operator or brackets.

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PostgreSQL Array Functions Overview

PostgreSQL Array functions play a crucial role in database management. This section will discuss some of the basic operations on arrays, their functionality, and examples. These operations will help us to handle arrays efficiently. Let’s discuss them one by one. But before hopping to functions, let’s look into the general syntax of the array in PostgreSQL.

Syntax of Array Data type in PostgreSQL

The syntax of PostgreSQL Array functions is as follows:

variable_name DATA TYPE[];  

where,

  •  variable_name is the name of the column in the table.
  • Data Type is any data type in PostgreSQL, either in-built or user-defined.

Creating Array in PostgreSQL Database

Suppose you have a customer_details table containing the various columns such as cust_id, customer_name, and customer_mobile_numbers. For the customer_mobile_numbers column, we use the one-dimensional array that contains several Mobile numbers that a customer might have.

CREATE TABLE customer_details (  
    cust_id serial PRIMARY KEY,  
    customer_name VARCHAR (200) ,  
    customer_mobile_numbers TEXT []  
);  

Output: When you run the above command, you will get the message window showing that the customer_details table was successfully created in your database.

Inserting Values in PostgreSQL Array

In PostgreSQL Array Function, the following statement illustrates to insert a new customer record into the customer details table.

Example:

INSERT INTO customer_details (customer_name , customer_mobile_numbers )  
VALUES('Maria Smith',ARRAY [ '(444)-333-1234','(555)-333-5432' ]); 

Output:

PostgreSQL Array Insert Command
Image Source: Self

Note: Here, we created an array with the ARRAY constructor to insert it into the customer details table. But there is another way to perform insertion on array in PostgreSQL database. The curly braces {} can also be used as mentioned below.

Insert Array Command with different format
Image Source: Self

Accessing Array in PostgreSQL

We have completed table creation and put entries into the customer details table. Its time to use the SELECT statement to return all rows of the customer details table:

Example:

SELECT customer_name, customer_mobile_numbers  
FROM customer_details;

Output: In the result of the above select statement, you will get the following output which displays all of the data in the customer details table:

Accessing Array PostgreSQL
Image Source: Self

You also can access arrays element with the help of subscript within square brackets []

Note: In PostgreSQL, arrays follow one-based indexing. It signifies that the first array element begins with the number 1. 

Example: If we want to retrieve the contact’s name of a given phone number, we can use the following query: 

SELECT
	customer_name, customer_mobile_numbers
FROM
	customer_details
WHERE
	customer_mobile_numbers [ 2 ] = '(308)-589-23458';

Output:

Accessing Array Element with Indexing
Image Source: Self

Updating Array in PostgreSQL

PostgreSQL allows you to update individual array elements or the entire array.

Example: The below-mentioned query will update the second phone number of the customer with id 3.

UPDATE customer_details  
SET customer_mobile_numbers [2] = '(178)-856-54366'  
WHERE cust_id = 3;  

Output: You can verify the new phone number using the SELECT statement.

SELECT customer_name, customer_mobile_numbers  
FROM customer_details;  
Updating Array PostgreSQL
Image Source: Self

The following command will update an array as a whole.

UPDATE customer_details  
SET customer_mobile_numbers = '{"(408)-589-5842","(408)-589-58423"}'  
WHERE cust_id = 1; 

Output:

Updating Whole Array PostgreSQL
Image Source: Self

Extend Array in PostgreSQL

An array’s values can be divided into rows. This is referred to as array expansion.

For example, in the Customer details table, specific customers have two contacts in the customer phone numbers array. These can be divided into various rows.

To extend an array to a list of rows, PostgreSQL provides the unnest() function. For example, the query below extends all phone numbers in the customer_mobile_numbers array.

SELECT
	customer_name,
	unnest(customer_mobile_numbers )
FROM
	customer_details;
Unnest Array PostgreSQL
Image Source: Self

Let’s say you need to know who owns the phone number (178)-856-54366. You can utilize the ANY() function regardless of the location inside the customer_mobile_numbers array, as shown below statement:

Example:

SELECT customer_name, customer_mobile_numbers  
FROM customer_details  
WHERE '(178)-856-54366' = ANY (customer_mobile_numbers); 

Output: In the result of the above query, you will get the following output.

Searching in PostgreSQL Array
Image Source: Self

Conclusion

This article demonstrated using instructions and examples to utilize the PostgreSQL array functions. The blog offered an overview of the PostgreSQL array, definitions of the array’s function, and examples. The lesson then demonstrated how to create a table in PostgreSQL, put array values into the table, filter rows using the array with the WHERE clause, and explain the unnest function.

Hopefully, you will try leveraging the PostgreSQL Array functions for your future projects. Feel free to leave a comment below expressing your thoughts or recommendations.

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