Introduction to Array in PostgreSQL
An array is having a very important role in PostgreSQL. We can create variable-length columns for a specific table. The data types defined in PostgreSQL have their own type like the character is having character[], the integer is having integer[] array, etc. If we have specified our own data types, then in the background, it will create an array type for the defined data type. We can define array type for any column of any data type like user-defined type, built-in type or enum types.
How to Create an Array in PostgreSQL?
To understand the data type insertion, let’s create a ‘student’ table with the following structure.
The student table consists of two columns:
- stud_id: The column is the primary key column that uniquely identifies the student.
- stud_name: The column is for showing student name
- stud_mob_num: The column stores the student’s contact information in the form of an array.
Let’s create the table by using the CREATE TABLE statement:
Query:
CREATE TABLE student (
stud_id serial NOT NULL PRIMARY KEY,
stud_name VARCHAR(80) NOT NULL ,
stud_mob_num TEXT []
);
Illustrate the result of the above statement table using the following snapshot and statement:
SELECT * FROM student;
How to Add Array Elements in PostgreSQL?
There are two ways to add elements in array type column; we will go through them one by one as follows:
1. Using [] Subscript Operator
We can insert the data using the subscript operator in the array column of the table as follows; here, we have to use single quotes around each element as we are using [] operator for insertion:
Query:
INSERT INTO student (stud_name, stud_mob_num)
VALUES
(
‘Oliver Jake’,
ARRAY [ '(+91)-9958655468',
'(+91)-9953246468' ]
),
(
‘Jack Connor’,
ARRAY [ '(+91)-9958655423',
'(+91)-9953246434' ]
);
Illustrate the result of the above statement table using the following snapshot and statement:
SELECT * FROM student;
Output:
2. Using {} Curly Braces
We can insert the data using curly braces in a column of the table as follows; here, we have to use double quotes around each array element as we are using curly {} braces for insertion:
Query:
INSERT INTO student (stud_name, stud_mob_num)
VALUES
(
'Harry Callum', '{ "(+91)-9958655468","(+91)-9953246468"}'
),
(
'Jacob John','{ "(+91)-9958633468","(+91)-9953243368"}'
);
Illustrate the result of the above statement table using the following snapshot and statement:
SELECT * FROM student;
Output:
Examples to Implement Array Operations in PostgreSQL
Below are the examples:
Example #1 – Access Array Data
- We can retrieve the data using the following snapshot and statement:
Query:
SELECT * FROM student;
Output:
- PostgreSQL allows us to access the array elements using the subscript [] operator
The array elements are numbered with one based indexing in PostgreSQL, which means the array’s base index is one. Consider the following example where we will get the student’s name and second mobile number with the help of the following statement:
Query:
SELECT
stud_name,
stud_mob_num [ 2 ]
FROM
student;
Output:
- PostgreSQL allows us to use array elements in the WHERE clause to filter out the rows.
Consider the following example where we will check for mobile number (+91)-9953243368 as the first mobile number with the help of the following statement:
Query:
SELECT
stud_name
FROM
student
WHERE
stud_mob_num [ 1 ] = '(+91)-9958633468';
Output:
Example #2 – Modify PostgreSQL Array Data
We can update the individual elements of an array or entire array.
- Update Individual Element
We will update the first mobile number of ‘Harry Callum’. Before updating Harry Callum’s first mobile number, we will execute the following statement and will have a look at the snapshot:
Query:
SELECT
stud_name,
stud_mob_num [ 1 ]
FROM
student
WHERE
stud_id = 3;
Output:
Now update the first mobile number of ‘Harry Callum’ using the following statement:
Query:
UPDATE student
SET stud_mob_num [ 1 ] = '(+91)-9958652222'
WHERE
stud_id = 3;
Illustrate the result of the above statement table using the following snapshot and statement:
SELECT
stud_name,
stud_mob_num [ 1 ]
FROM
student
WHERE
stud_id = 3;
Output:
- Update the Entire Array
Now we will update the entire mobile number array of ‘Harry Callum’ using the following statement:
Query:
UPDATE student
SET stud_mob_num = '{"(+91)-9958651111"}'
WHERE
stud_id = 3;
Illustrate the result of the above statement table using the following snapshot and statement:
SELECT
stud_name,
stud_mob_num
FROM
student
WHERE
stud_id = 3;
Output:
- PostgreSQL Array Data Search
With the ANY() function provided, we can find any record if beforehand we know the mobile number of the student irrespective of the position in the array, consider the following statement and snapshot:
Query:
SELECT
stud_name,
stud_mob_num
FROM
student
WHERE
'(+91)-9958633468' = ANY (stud_mob_num);
Output:
- PostgreSQL Array Expand
With the unnest() function provided by PostgreSQL to expand an array to a list of rows. Consider the following statement to expand mobile numbers of the stud_mob_num array.
Query:
SELECT
stud_name,
unnest(stud_mob_num)
FROM
student;
Output:
Advantages of Array in PostgreSQL
- We can access the elements with the help of the index, which leads to faster access.
- PostgreSQL provides various functions to work with an array.
- We can insert, update the array element by using an index.
- Insertion on the array element is very easy as we can use multiple syntaxes like [] operator or {} braces.
Conclusion
We Frome the above article, we hope you have understood how to use the PostgreSQL Array data type and how the PostgreSQL array data type works to store the data. Also, we have added some examples of array type to understand it in detail.
Recommended Articles
This is a guide to Array in PostgreSQL. Here we discuss the Introduction and how to Create & Add Array in PostgreSQL and the practical examples and different subquery expressions. You can also go through our suggested articles to learn more –
