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我就废话不多说了,大家还是直接看代码吧~
SELECT sum(aa) as "recordNumber" FROM table SELECT sum(aa) as recordNumber FROM table
postgis查询字段是将字段字段转为小写,如果需要大写的字符,需要加双引号
补充:Postgresql中表名、列名、用户名大小写问题
注意:是双引号,单引号可能会被解析成普通字符,因而是不识别的字段
highgo=# create table "ExChange" (id int); CREATE TABLE highgo=# create table ExChange (id int); CREATE TABLE highgo=# \d List of relations Schema | Name | Type | Owner ----------------+----------+-------+-------- oracle_catalog | dual | view | highgo public | ExChange | table | highgo public | exchange | table | highgo public | myt | table | highgo public | t1 | table | highgo public | tran | table | highgo (6 rows) highgo=# insert into exchange values (1); INSERT 0 1 highgo=# insert into "ExChange" values (2); INSERT 0 1 highgo=# select * FROM exchange ; id ---- 1 (1 row) highgo=# select * FROM ExChange ; id ---- 1 (1 row) highgo=# select * FROM "ExChange" ; id ---- 2 (1 row) highgo=# insert into ExChange values (2); INSERT 0 1 highgo=# select * FROM "ExChange" ; id ---- 2 (1 row) highgo=# select * FROM exchange ; id ---- 1 2 (2 rows)
> 从上面可以看出,如果不加双引号,那么表名都会被转化为小写。如果想要大小写混用,需要添加双引号。
highgo=# create table exchange (ID int,id int); ERROR: 42701: column "id" specified more than once highgo=# create table exchange (ID int,name text); CREATE TABLE highgo=# select id from exchange ; id ---- (0 rows) highgo=# select ID from exchange ; id ---- (0 rows) highgo=# select "ID" from exchange ; ERROR: 42703: column "ID" does not exist LINE 1: select "ID" from exchange ; highgo=# \d exchange Table "public.exchange" Column | Type | Modifiers --------+---------+----------- id | integer | name | text | highgo=# \du List of roles Role name | Attributes | Member of -----------+------------------------------------------------------------+----------- aaa | | {} gpadmin | Superuser, Create role, Create DB | {} highgo | Superuser, Create role, Create DB, Replication, Bypass RLS | {} replica | Replication | {} highgo=# create table AAA; ERROR: 42601: syntax error at or near ";" LINE 1: create table AAA; ^ highgo=# create user AAA; ERROR: 42710: role "aaa" already exists highgo=# create user "AAA"; CREATE ROLE highgo=# \du List of roles Role name | Attributes | Member of -----------+------------------------------------------------------------+----------- AAA | | {} aaa | | {} gpadmin | Superuser, Create role, Create DB | {} highgo | Superuser, Create role, Create DB, Replication, Bypass RLS | {} replica | Replication | {}
实验证明,字段与用户同样会被自动转化为小写,除非添加双引号。 其实最好的办法就是全部用小写,这样才能尽量减少问题的出现。
以上为个人经验,希望能给大家一个参考,也希望大家多多支持。如有错误或未考虑完全的地方,望不吝赐教。
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