varchar2转clob

--修改dishdetail字段名dishdetailbackALTER TABLE dispatch_dish RENAME COLUMN dishdetail TO dishdetailback;--创建一个dishdetail字段  类型是clobALTER TABLE dispatch_dish ADD dishdetail  clob;--把dishdetailback的值都放到dishdetail中UPDATE dispatch_dish SET dishdetail =dishdetailback  -- CAST(dishdetailback AS clob);--删除dishdetailback字段ALTER TABLE dispatch_dish DROP COLUMN dishdetailback;

 

 

要把一个varchar2的字段修改成clob类型，前提是已存在的数据不能够改变。

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