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原文： https://blog.csdn.net/pg_hgdb/article/details/79227237

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 TABLEhighgo=# create table ExChange (id int);CREATE TABLEhighgo=# \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 1highgo=# insert into "ExChange" values (2);INSERT 0 1highgo=# 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 1highgo=# 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 oncehighgo=# create table exchange (ID int,name text);CREATE TABLEhighgo=# 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 existLINE 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 existshighgo=# create user "AAA";CREATE ROLEhighgo=# \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。