SQL> create table A ("UserName" varchar2(10));Table createdSQL> select * from A;UserName ----------SQL> drop table A;Table droppedSQL> create table A (UserName varchar2(10));Table createdSQL> select UserName from A;USERNAME ----------SQL> select username as "UserName" from A;UserName ----------
SQL> create table A ("UserName" varchar2(10));表已创建。SQL> select "UserName" from A;未选定行SQL> select UserName from A; select UserName from A * 第 1 行出现错误: ORA-00904: "USERNAME": 标识符无效 SQL> drop table A;表已删除。SQL> create table A (UserName varchar2(10));表已创建。SQL> select UserName from A;未选定行SQL>最好不用"USERNAME" ,否则以后查询有问题
如果你是指数据,则需要用函数upper,lower进行转换.
----------SQL> drop table A;Table droppedSQL> create table A (UserName varchar2(10));Table createdSQL> select UserName from A;USERNAME
----------SQL> select username as "UserName" from A;UserName
----------
名称 是否为空? 类型
----------------------------------------------------- -------- ------------------
UserName NUMBER(38)
CREATE TABLE TAB("Aus" VARCHAR2(1));
select UserName from A
*
第 1 行出现错误:
ORA-00904: "USERNAME": 标识符无效
SQL> drop table A;表已删除。SQL> create table A (UserName varchar2(10));表已创建。SQL> select UserName from A;未选定行SQL>最好不用"USERNAME" ,否则以后查询有问题
如果你是指数据,则需要用函数upper,lower进行转换.加了双引号,
以后就要严格按照双引号内的格式写SQL
加了双引号以后Oracle就开始区别大小写了,如果你的程序里sql不是严格写的话,都会报错