PostgreSQL/Array/Array Slice

An array slice is denoted by writing lower-bound:upper-bound for one or more array dimensions

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=# -- An array slice is denoted by writing lower-bound:upper-bound for one or more array dimensions.
postgres=#
postgres=# SELECT schedule[1:2][1:1] FROM sal_emp WHERE name = "Bill";
        schedule
------------------------
 {{meeting},{training}}
(1 row)
postgres=#
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=#
postgres=#

Selecting array values with slices

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=# INSERT INTO book VALUES (103, "{"AAA", "VVVV"}");
INSERT 0 1
postgres=#
postgres=#
postgres=# -- Selecting array values with slices
postgres=#
postgres=# SELECT titles[1:2] FROM book;
     titles
----------------
 {"AAA"s VVVV"}
 {AAA,VVVV}
(2 rows)
postgres=#
postgres=# drop table book;
DROP TABLE
postgres=#