postgresql查詢自動將大寫的名稱轉換為小寫的案例

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我就廢話不多說瞭，大傢還是直接看代碼吧~

 SELECT sum(aa) as "recordNumber" FROM table
 SELECT sum(aa) as recordNumber FROM table

postgis查詢字段是將字段字段轉為小寫，如果需要大寫的字符，需要加雙引號

補充：Postgresql中表名、列名、用戶名大小寫問題

註意：是雙引號，單引號可能會被解析成普通字符，因而是不識別的字段

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)

> 從上面可以看出，如果不加雙引號，那麼表名都會被轉化為小寫。如果想要大小寫混用，需要添加雙引號。

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      | {}

實驗證明，字段與用戶同樣會被自動轉化為小寫，除非添加雙引號。 其實最好的辦法就是全部用小寫，這樣才能盡量減少問題的出現。

以上為個人經驗，希望能給大傢一個參考，也希望大傢多多支持WalkonNet。如有錯誤或未考慮完全的地方，望不吝賜教。

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