修复了oracle sql查询的标题

我正在尝试编写一个select查询，在一个列中包含一个连接的列，列名称非常严格，并且没有撇号

这是主要思想

SELECT COLUMN1|| COLUMN2 || COLUMN3 AS 'AN ALIAS WITH MORE THAN 30 CHARACTER' FROM DUAL

（AS）不起作用，并且因为我正在使用Oracle版本12，所以（“”）将触发一个错误（标识符太长）

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有没有办法做到这一点

答案很简单：你不能。这叫做限制。不过，我不确定我是否理解您提到的12c数据库版本，因为它支持超过30个字符的标识符，而较低版本（如11g）则不支持

例如：

SQL> select * From v$version where rownum = 1;

BANNER
--------------------------------------------------------------------------------
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production

SQL> select dummy as "an alias with more than 30 characters" from dual;
select dummy as "an alias with more than 30 characters" from dual
                *
ERROR at line 1:
ORA-00972: identifier is too long

---

SQL> select * From v$version where rownum = 1;

BANNER                                                                               CON_ID
-------------------------------------------------------------------------------- ----------
Oracle Database 12c Enterprise Edition Release 12.2.0.1.0 - 64bit Production              0

SQL> select 'a234567890123456789012345678901234567890' "an alias with more than 30 characters" from dual;

an alias with more than 30 characters
----------------------------------------
a234567890123456789012345678901234567890

SQL>