PostgreSQL/Array/Array Column Select

Accessing two dimensional Arrays

   <source lang="sql">

postgres=# CREATE TABLE sal_emp ( postgres(# name text, postgres(# pay_by_quarter integer[], postgres(# schedule text[][] postgres(# ); CREATE TABLE postgres=# postgres=# INSERT INTO sal_emp postgres-# VALUES ("Bill", postgres(# ARRAY[10000, 10000, 10000, 10000], postgres(# ARRAY[["meeting", "lunch"], ["training", "presentation"]]); INSERT 0 1 postgres=# postgres=# INSERT INTO sal_emp postgres-# VALUES ("Carol", postgres(# ARRAY[20000, 25000, 25000, 25000], postgres(# ARRAY[["breakfast", "consulting"], ["meeting", "lunch"]]); INSERT 0 1 postgres=# postgres=# -- Accessing Arrays postgres=# postgres=# SELECT name FROM sal_emp WHERE pay_by_quarter[1] <> pay_by_quarter[2];

name

---

Carol

(1 row) postgres=# postgres=# SELECT * FROM sal_emp;

name  |      pay_by_quarter       |                 schedule

---

+---------------------------+-------------------------------------------

Bill  | {10000,10000,10000,10000} | {{meeting,lunch},{training,presentation}}
Carol | {20000,25000,25000,25000} | {{breakfast,consulting},{meeting,lunch}}

(2 rows) postgres=# postgres=# postgres=# drop table sal_emp; DROP TABLE postgres=# postgres=#

      </source>
   
  

Array Input and Output Syntax

   <source lang="sql">

postgres=# postgres=# -- Array Input and Output Syntax postgres=# SELECT 1 || ARRAY[2,3] AS array;

    array

---

[0:2]={1,2,3}

(1 row) postgres=# postgres=#

      </source>
   
  

Reference array element

   <source lang="sql">

postgres=# postgres=# postgres=# CREATE TABLE sal_emp ( postgres(# name text, postgres(# pay_by_quarter integer[], postgres(# schedule text[][] postgres(# ); CREATE TABLE postgres=# postgres=# INSERT INTO sal_emp postgres-# VALUES ("Bill", postgres(# ARRAY[10000, 10000, 10000, 10000], postgres(# ARRAY[["meeting", "lunch"], ["training", "presentation"]]); INSERT 0 1 postgres=# postgres=# INSERT INTO sal_emp postgres-# VALUES ("Carol", postgres(# ARRAY[20000, 25000, 25000, 25000], postgres(# ARRAY[["breakfast", "consulting"], ["meeting", "lunch"]]); INSERT 0 1 postgres=# postgres=# -- Retrieves the third quarter pay of all employees: postgres=# postgres=# SELECT pay_by_quarter[3] FROM sal_emp;

pay_by_quarter

---

         10000
         25000

(2 rows) postgres=# postgres=# SELECT * FROM sal_emp;

name  |      pay_by_quarter       |                 schedule

---

+---------------------------+-------------------------------------------

Bill  | {10000,10000,10000,10000} | {{meeting,lunch},{training,presentation}}
Carol | {20000,25000,25000,25000} | {{breakfast,consulting},{meeting,lunch}}

(2 rows) postgres=# postgres=# drop table sal_emp; DROP TABLE postgres=# postgres=#

      </source>
   
  

Searching in Arrays

   <source lang="sql">

postgres=# postgres=# postgres=# CREATE TABLE sal_emp ( postgres(# name text, postgres(# pay_by_quarter integer[], postgres(# schedule text[][] postgres(# ); CREATE TABLE postgres=# postgres=# INSERT INTO sal_emp postgres-# VALUES ("Bill", postgres(# ARRAY[10000, 10000, 10000, 10000], postgres(# ARRAY[["meeting", "lunch"], ["training", "presentation"]]); INSERT 0 1 postgres=# postgres=# INSERT INTO sal_emp postgres-# VALUES ("Carol", postgres(# ARRAY[20000, 25000, 25000, 25000], postgres(# ARRAY[["breakfast", "consulting"], ["meeting", "lunch"]]); INSERT 0 1 postgres=# postgres=# SELECT * FROM sal_emp;

name  |      pay_by_quarter       |                 schedule

---

+---------------------------+-------------------------------------------

Bill  | {10000,10000,10000,10000} | {{meeting,lunch},{training,presentation}}
Carol | {20000,25000,25000,25000} | {{breakfast,consulting},{meeting,lunch}}

(2 rows) postgres=# -- Searching in Arrays postgres=# SELECT * FROM sal_emp WHERE pay_by_quarter[1] = 10000 OR postgres-# pay_by_quarter[2] = 10000 OR postgres-# pay_by_quarter[3] = 10000 OR postgres-# pay_by_quarter[4] = 10000;

name |      pay_by_quarter       |                 schedule

---

+---------------------------+-------------------------------------------

Bill | {10000,10000,10000,10000} | {{meeting,lunch},{training,presentation}}

(1 row) postgres=# postgres=# postgres=# drop table sal_emp; DROP TABLE postgres=#

      </source>
   
  

SELECT ARRAY[1,2] || ARRAY3,4 AS array

   <source lang="sql">

postgres=# postgres=# SELECT ARRAY[1,2] || ARRAY3,4 AS array;

         array

---

[0:1][1:2]={{1,2},{3,4}}

(1 row) postgres=#

      </source>
   
  

Select array column by index

   <source lang="sql">

postgres=# postgres=# postgres=# CREATE TABLE book (id integer,titles text[]); CREATE TABLE postgres=# postgres=# INSERT INTO book VALUES (102, "{"AAA\"s VVVV"}"); INSERT 0 1 postgres=# postgres=# INSERT INTO book VALUES (103, "{"AAA", "VVVV"}"); INSERT 0 1 postgres=# postgres=# postgres=# SELECT titles[2] FROM book;

titles

---

VVVV

(2 rows) postgres=# postgres=# SELECT titles[2] FROM book WHERE titles[2] IS NOT NULL;

titles

---

VVVV

(1 row) postgres=# postgres=# drop table book; DROP TABLE postgres=# postgres=#

      </source>
   
  

Selecting array values with subscripts

   <source lang="sql">

postgres=# postgres=# -- Selecting array values with subscripts postgres=# postgres=# CREATE TABLE book (id integer,titles text[]); CREATE TABLE postgres=# postgres=# INSERT INTO book VALUES (102, "{"AAA\"s VVVV"}"); INSERT 0 1 postgres=# postgres=# INSERT INTO book VALUES (103, "{"AAA", "VVVV"}"); INSERT 0 1 postgres=# postgres=# SELECT titles[1] FROM book;

  titles

---

AAA"s VVVV
AAA

(2 rows) postgres=# postgres=# drop table book; DROP TABLE postgres=# postgres=#

      </source>
   
  

Selecting entire array values

   <source lang="sql">

postgres=# postgres=# -- Selecting entire array values postgres=# postgres=# postgres=# CREATE TABLE book (id integer,titles text[]); CREATE TABLE postgres=# postgres=# INSERT INTO book VALUES (102, "{"AAA\"s VVVV"}"); INSERT 0 1 postgres=# postgres=# INSERT INTO book VALUES (103, "{"AAA", "VVVV"}"); INSERT 0 1 postgres=# postgres=# SELECT titles FROM book;

    titles

---

{"AAA"s VVVV"}
{AAA,VVVV}

(2 rows) postgres=# postgres=# drop table book; DROP TABLE postgres=# postgres=#

      </source>
   
  

Selecting From a Multi-Dimensional Array

   <source lang="sql">

postgres=# postgres=# CREATE TABLE authors (id integer,titles text[][]); CREATE TABLE postgres=# postgres=# INSERT INTO authors postgres-# VALUES (102, postgres(# "{{"J T", "T S"}, postgres"# {"C D", "G E"}, postgres"# {"A D", "A L"}}"); INSERT 0 1 postgres=# postgres=# -- Selecting From a Multi-Dimensional Array postgres=# postgres=# SELECT titles[1][1] AS author, titles[1][2] AS title FROM authors;

author | title

---

+-------

J T    | T S

(1 row) postgres=# postgres=# drop table authors; DROP TABLE postgres=# postgres=#

      </source>
   
  

Specify non-default array subscripts in an array literal

   <source lang="sql">

postgres=# -- Specify non-default array subscripts in an array literal postgres=# postgres=# SELECT f1[1][-2][3] AS e1, f1[1][-1][5] AS e2 postgres-# FROM (SELECT "[1:1][-2:-1][3:5]={{{1,2,3},{4,5,6}}}"::int[] AS f1) AS ss;

e1 | e2

---

+----

 1 |  6

(1 row) postgres=# postgres=#

      </source>
   
  

Use array constant in select statement

   <source lang="sql">

postgres=# postgres=# SELECT ARRAY[1,2,3+4];

 array

---

{1,2,7}

(1 row)

      </source>
   
  

Using two dimension array

   <source lang="sql">

postgres=# postgres=# SELECT ARRAY[[1,2],[3,4]];

    array

---

{{1,2},{3,4}}

(1 row) postgres=#

      </source>