postgresql查询自动将大写的名称转换为小写的案例

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。