postgresql查询自动将大写的名称转换为小写的案例_PostgreSQL

postgresql查询自动将大写的名称转换为小写的案例

2021-04-08 18:36pigs2018 PostgreSQL

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我就废话不多说了，大家还是直接看代码吧~

1 2	`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      | {}