文档解释
ORA-12994: drop column option only allowed once in statement
Cause: An attempt was made to repeat the drop column option in a single statement.
Action: Separate drop column options into different statements and resubmit statements.
ORA-12994：Drop列选项仅在一个语句中允许使用一次。
官方解释
常见案例
CREATE TABLE Table1 ( Column1 INT, Column2 INT); ALTER TABLE Table1 DROP COLUMN Column1; DROP COLUMN Column2;
正常处理方法及步骤
要解决此错误，只需将单个语句中的drop column/table操作分离开，例如：
CREATE TABLE Table1 ( Column1 INT, Column2 INT); ALTER TABLE Table1 DROP COLUMN Column1; ALTER TABLE Table1 DROP COLUMN Column2;
