postgresql----数组类型和函数

---1*4的一维数组
test=# select array[1,2,3,4];
array
-----------
{1,2,3,4}
(1 row)

--2*2的二维数组
test=# select array[[1,2],[3,4]];
array
---------------
{{1,2},{3,4}}
(1 row)
--1*2的二维数组，基本类型为box矩形类型，且和上面相比box类型元素之间是以分号分隔的，其他所有类型的数据都是以逗号分隔的
test=# select array[box'(1,1),(0,0)',box'(0,0),(-1,-1)'];
array
-----------------------------
{(1,1),(0,0);(0,0),(-1,-1)}
(1 row)

test=# create table tbl_array(a int[],b varchar(32)[][],c int);
CREATE TABLE
test=# insert into tbl_array (a,b,c) values (array[1,2],array[[1,2,3],[4,5,6]],1);
INSERT 0 1
test=# insert into tbl_array (a,b,c) values (array[1,2,3],array[[1,2],[4,5]],2);
INSERT 0 1
test=# select * from tbl_array ;
a    |         b         | c
---------+-------------------+---
{1,2}   | {{1,2,3},{4,5,6}} | 1
{1,2,3} | {{1,2},{4,5}}     | 2
(2 rows)

test=# select a[1],b[2] from tbl_array where c = 1;
a | b
---+---
1 |
(1 row)

test=# select a[1],b[2][1] from tbl_array where c = 1;
a | b
---+---
1 | 4
(1 row)

test=# select a[1],b[2][4] from tbl_array where c = 1;
a | b
---+---
1 |
(1 row)

test=# update tbl_array set a[1] = 200 where a[1] = 1;
UPDATE 1
test=# select a[1],b[2][4] from tbl_array ;
a  | b
-----+---
100 |
200 |
(2 rows)

test=# select a[2:3] from tbl_array ;
a
-------
{2}
{2,3}
(2 rows)

test=# select a[1:3] from tbl_array ;
a
-----------
{100,2}
{200,2,3}
(2 rows)

array_append

array_cat

array_ndims

array_dims

array_fill

array_length

array_lower

array_position

array_positions

array_prepend

array_remove

array_replace

array_to_string

array_upper

cardinality

string_to_array

unnest

unnest