2019独角兽企业重金招聘Python工程师标准>>> 
数组字段类型
db01=# create table t_array(id int,array_1 int[],array_2 text[][]);
CREATE TABLE
db01=# \d t_array
Table "hippo.t_array"
Column | Type | Modifiers
---------+-----------+-----------
id | integer |
array_1 | integer[] |
array_2 | text[] |
虽然我指定了一个是一维数组,一个是二维数组,但是表结构显示的都是一维数组 pgadmin中看结构,array_2显示是[][].
数组构造插入
我们插入数据测试一下
db01=# insert into t_array values(1,'{1,2,3}','{"aaa","bbb","ccc"}');
INSERT 0 1
db01=# insert into t_array values(1,'{{1,2,3},{4,5,6},{7,8,9}}','{{"aaa","bbb","ccc"},{"ddd","eee","fff"},{"ggg","hhh","iii"}}');
INSERT 0 1
db01=# select * from t_array;
id | array_1 | array_2
----+---------------------------+---------------------------------------------
1 | {1,2,3} | {aaa,bbb,ccc}
1 | {{1,2,3},{4,5,6},{7,8,9}} | {{aaa,bbb,ccc},{ddd,eee,fff},{ggg,hhh,iii}}
(2 rows)
不管一维二维几维都可以插入数据
使用array构造器语法
db01=# insert into t_array values(2,array[1,2,3,4],array[['a','b'],['c','d']]);
INSERT 0 1
即使申明的是一维数组,也可以插入多维数组
db01=# insert into t_array values(3,array[[[1,2],[3,4]],[[5,6],[6,7]],[[8,9],[9,10]]],array['a','b','c']);
INSERT 0 1
db01=# select * from t_array;
id | array_1 | array_2
----+----------------------------------------------+---------------------------------------------
1 | {1,2,3} | {aaa,bbb,ccc}
1 | {{1,2,3},{4,5,6},{7,8,9}} | {{aaa,bbb,ccc},{ddd,eee,fff},{ggg,hhh,iii}}
2 | {1,2,3,4} | {{a,b},{c,d}}
3 | {{{1,2},{3,4}},{{5,6},{6,7}},{{8,9},{9,10}}} | {a,b,c}
数组取值方法
###下标 ### db01=# select id,array_1[1],array_2[2][1],array_1[3][2][2] from t_array; id | array_1 | array_2 | array_1 ----+---------+---------+--------- 1 | 1 | |
1 | | ddd |
2 | 1 | c |
3 | | | 10 (4 rows)
通过下标来取数组中的值,下标的维度跟存储的维度对应
###数组slices###
db01=# select id,array_1[2:3][1:2] from t_array;
id | array_1
----+--------------------------------
1 | {}
1 | {{4,5},{7,8}}
2 | {}
3 | {{{5,6},{6,7}},{{8,9},{9,10}}}
(4 rows)
db01=# select array_1,array_1[-2:2] from t_array;
array_1 | array_1
----------------------------------------------+-------------------------------
{1,2,3} | {1,2}
{{1,2,3},{4,5,6},{7,8,9}} | {{1,2,3},{4,5,6}}
{1,2,3,4} | {1,2}
{{{1,2},{3,4}},{{5,6},{6,7}},{{8,9},{9,10}}} | {{{1,2},{3,4}},{{5,6},{6,7}}}
(4 rows)
有点像字符串的截取,返回的还是同维度的array
针对的都是元素
##数组修改##
###整个字段修改###
db01=# update t_array set array_2 = '{x,y,z}' where id = 3;
UPDATE 1
db01=# select * from t_array where id = 3;
id | array_1 | array_2
----+----------------------------------------------+---------
3 | {{{1,2},{3,4}},{{5,6},{6,7}},{{8,9},{9,10}}} | {x,y,z}
(1 row)
db01=# update t_array set array_2 = array[[['x','y','z'],['h','i','j']],[['a','b','c'],['q','w','e']]] where id =3;
UPDATE 1
db01=# select * from t_array where id = 3;
id | array_1 | array_2
----+----------------------------------------------+---------------------------------------
3 | {{{1,2},{3,4}},{{5,6},{6,7}},{{8,9},{9,10}}} | {{{x,y,z},{h,i,j}},{{a,b,c},{q,w,e}}}
(1 row)
只要符合数组类型,不管几维
###数组元素修改###
db01=# update t_array set array_2[2][2][1] = 'k',array_2[2:2][1:1][1:3]='{"o","p","q"}' where id = 3;
UPDATE 1
db01=# select array_2 from t_array where id =3;
array_2
---------------------------------------
{{{x,y,z},{h,i,j}},{{o,p,q},{k,w,e}}}
(1 row)
通过下标或者slice进行修改
数组中查找
通过下标的方法已经知道,语法any是在数组中搜索匹配的
db01=# select array_1,8 = any(array_1) from t_array;
{1,2,3} | f
{{1,2,3},{4,5,6},{7,8,9}} | t
{1,2,3,4} | f
{{{1,2},{3,4}},{{5,6},{6,7}},{{8,9},{9,10}}} | t
[-1:1]={1,2,3} | f
any 要写在等号后面,写前面会报错
any 表示只要满足有这个元素在里面
还有个all,代表所有元素都要满足
db01=# select 1 = all(array[1,2,3,4]),1 = all(array[[1,1],[1,1],[1,1]]);
f | t
写where语句的时候有用
未完待续......
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