ORA-12812: only one PARALLEL or NOPARALLEL clause may be specified

文档解释

ORA-12812: only one PARALLEL or NOPARALLEL clause may be specified

Cause: PARALLEL was specified more than once, NOPARALLEL was specified more than once, or both PARALLEL and NOPARALLEL were specified in a CREATE TABLE, CLUSTER, or INDEX or in an ALTER TABLE or CLUSTER statement, or in a RECOVER command.

Action: Remove all but one of the PARALLEL or NOPARALLEL clauses and reissue the statement.

ORA-12812错误是表示在一个SQL语句中只能包含一个PARALLEL或NOPARALLEL子句。

官方描述：

ORA-12812: 只能指定一个PARALLEL或NOPARALLEL子句

这个错误消息指示只能在某个SQL语句中指定一个PARALLEL或NOPARALLEL子句。

常见案例

当一个SQL语句中同时包含PARALLEL和NOPARALLEL子句时，您将收到此错误代码：

SELECT * FROM table

PARALLEL(20) NOPARALLEL;

正常处理方法及步骤

要解决ORA-12812错误，请将SQL语句更改为只包含一个PARALLEL或NOPARALLEL子句，例如：

SELECT * FROM table PARALLEL(20); // 使用PARALLEL子句

或

SELECT * FROM table NOPARALLEL; // 使用NOPARALLEL子句