我就廢話不多說(shuō)了，大家還是直接看代碼吧~
SELECT sum(aa) as "recordNumber" FROM table
SELECT sum(aa) as recordNumber FROM table
postgis查詢(xún)字段是將字段字段轉(zhuǎn)為小寫(xiě)，如果需要大寫(xiě)的字符，需要加雙引號(hào)
補(bǔ)充：Postgresql中表名、列名、用戶(hù)名大小寫(xiě)問(wèn)題
注意：是雙引號(hào)，單引號(hào)可能會(huì)被解析成普通字符，因而是不識(shí)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(hào)，那么表名都會(huì)被轉(zhuǎn)化為小寫(xiě)。如果想要大小寫(xiě)混用，需要添加雙引號(hào)。
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(shí)驗(yàn)證明，字段與用戶(hù)同樣會(huì)被自動(dòng)轉(zhuǎn)化為小寫(xiě)，除非添加雙引號(hào)。 其實(shí)最好的辦法就是全部用小寫(xiě)，這樣才能盡量減少問(wèn)題的出現(xiàn)。
以上為個(gè)人經(jīng)驗(yàn)，希望能給大家一個(gè)參考，也希望大家多多支持腳本之家。如有錯(cuò)誤或未考慮完全的地方，望不吝賜教。
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