| =@H_502_10@ | equal@H_502_10@ | ARRAY[1.1,2.1,3.1]::int[] = ARRAY[1,2,3]@H_502_10@ | t@H_502_10@ |
| <>@H_502_10@ | not equal@H_502_10@ | ARRAY[1,3] <> ARRAY[1,4]@H_502_10@ | t@H_502_10@ |
| <@H_502_10@ | less than@H_502_10@ | ARRAY[1,3] < ARRAY[1,4]@H_502_10@ | t@H_502_10@ |
| >@H_502_10@ | greater than@H_502_10@ | ARRAY[1,4,3] > ARRAY[1,4]@H_502_10@ | t@H_502_10@ |
| <=@H_502_10@ | less than or equal@H_502_10@ | ARRAY[1,3] <= ARRAY[1,3]@H_502_10@ | t@H_502_10@ |
| >=@H_502_10@ | greater than or equal@H_502_10@ | ARRAY[1,3] >= ARRAY[1,3]@H_502_10@ | t@H_502_10@ |
| @>@H_502_10@ | contains@H_502_10@ | ARRAY[1,3] @> ARRAY[3,1]@H_502_10@ | t@H_502_10@ |
| <@@H_502_10@ | is contained by@H_502_10@ | ARRAY[2,7] <@ ARRAY[1,7,6]@H_502_10@ | t@H_502_10@ |
| &&@H_502_10@ | overlap (have elements in common)@H_502_10@ | ARRAY[1,3] && ARRAY[2,1]@H_502_10@ | t@H_502_10@ |
| ||@H_502_10@ | array-to-array concatenation@H_502_10@ | ARRAY[1,3] || ARRAY[4,5,6]@H_502_10@ | {1,3,6}@H_502_10@ |
| ||@H_502_10@ | array-to-array concatenation@H_502_10@ | ARRAY[1,3] || ARRAY[[4,6],[7,8,9]]@H_502_10@ | {{1,3},{4,6},{7,9}}@H_502_10@ |
| ||@H_502_10@ | element-to-array concatenation@H_502_10@ | 3 || ARRAY[4,6]@H_502_10@ | {3,6}@H_502_10@ |
| ||@H_502_10@ | array-to-element concatenation@H_502_10@ | ARRAY[4,6] || 7@H_502_10@ | {4,6,7}@H_502_10@ |
Array Functions
array_append(anyarray,anyelement)@H_502_10@
| anyarray@H_502_10@ | append an element to the end of an array@H_502_10@ | array_append(ARRAY[1,2],3)@H_502_10@ | {1,3}@H_502_10@ |
array_cat(anyarray,anyarray)@H_502_10@
| anyarray@H_502_10@ | concatenate two arrays@H_502_10@ | array_cat(ARRAY[1,3],ARRAY[4,5])@H_502_10@ | {1,5}@H_502_10@ |
array_ndims(anyarray)@H_502_10@
| int@H_502_10@ | returns the number of dimensions of the array@H_502_10@ | array_ndims(ARRAY[[1,[4,6]])@H_502_10@ | 2@H_502_10@ |
array_dims(anyarray)@H_502_10@
| text@H_502_10@ | returns a text representation of array's dimensions@H_502_10@ | array_dims(ARRAY[[1,6]])@H_502_10@ | [1:2][1:3]@H_502_10@ |
array_fill(anyelement,int[],[,int[]])@H_502_10@
| anyarray@H_502_10@ | returns an array initialized with supplied value and dimensions,optionally with lower bounds other than 1@H_502_10@ | array_fill(7,ARRAY[3],ARRAY[2])@H_502_10@ | [2:4]={7,7}@H_502_10@ |
array_length(anyarray,int)@H_502_10@
| int@H_502_10@ | returns the length of the requested array dimension@H_502_10@ | array_length(array[1,1)@H_502_10@ | 3@H_502_10@ |
array_lower(anyarray,int)@H_502_10@
| int@H_502_10@ | returns lower bound of the requested array dimension@H_502_10@ | array_lower('[0:2]={1,3}'::int[],1)@H_502_10@ | 0@H_502_10@ |
array_prepend(anyelement,anyarray)@H_502_10@
| anyarray@H_502_10@ | append an element to the beginning of an array@H_502_10@ | array_prepend(1,ARRAY[2,3])@H_502_10@ | {1,3}@H_502_10@ |
array_to_string(anyarray,text [,text])@H_502_10@
| text@H_502_10@ | concatenates array elements using supplied delimiter and optional null string@H_502_10@ | array_to_string(ARRAY[1,NULL,5],','*')@H_502_10@ | 1,*,5@H_502_10@ |
array_upper(anyarray,int)@H_502_10@
| int@H_502_10@ | returns upper bound of the requested array dimension@H_502_10@ | array_upper(ARRAY[1,7],1)@H_502_10@ | 4@H_502_10@ |
string_to_array(text,text])@H_502_10@
| text[]@H_502_10@ | splits string into array elements using supplied delimiter and optional null string@H_502_10@ | string_to_array('xx~^~yy~^~zz','~^~','yy')@H_502_10@ | {xx,zz}@H_502_10@ |
unnest(anyarray)@H_502_10@
| setof anyelement@H_502_10@ | expand an array to a set of rows@H_502_10@ | unnest(ARRAY[1,2])@H_502_10@ | 1 2(2 rows)@H_502_10@ |
下面列举几个可能不容易查询出来的东西：
1. pg中查看两个数组之间有多少个重叠的数据 并且去重的方法
example :
mrapp=# SELECT array( select UNNEST(array[1,3]) INTERSECT SELECT
UNNEST(array[2,4]) );
array
-------
{2,3}
(1 行记录)
2. PG中没有现成的查询一个数组是否包含一个值的方法，但可以有替代方法
example : 查询 数组 {2,5} 中是否包含4
1> mrapp=# select array[2,5] @> array[4];
?column?
----------
t
(1 行记录)
2> 自己封装函数 通过迭代循环吧
mrapp=# create or replace function array_contains_value(integer[],integer) retu
rns boolean as
mrapp-# $BODY$
mrapp$# declare
mrapp$# index integer;
mrapp$# begin
mrapp$# for index in 1..array_length($1,1) loop
mrapp$# if $1[index] = $2 then
mrapp$# return true;
mrapp$# end if;
mrapp$# end loop;
mrapp$# return false;
mrapp$# end;
mrapp$# $BODY$
mrapp-# language plpgsql;
CREATE FUNCTION
mrapp=# select array_contains_value(array[2,4);
array_contains_value
----------------------
t
(1 行记录)
3. 数组转字符串
