SQL dbms_lob.getlength() 与 length() 在 oracle 中查找 blob 大小
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dbms_lob.getlength() vs. length() to find blob size in oracle
提问by Vincent Malgrat
I'm getting the same results from
我得到了相同的结果
select length(column_name) from table
as
作为
select dbms_lob.getlength(column_name) from table
select dbms_lob.getlength(column_name) from table
However, the answers to
this questionseem to favor using dbms_lob.getlength().
然而，这个问题的答案
似乎倾向于使用dbms_lob.getlength().
Is there any benefit to using dbms_lob.getlength()?
使用有什么好处dbms_lob.getlength()吗？
If it changes the answer, I know all of the blobs are .bmp images (never worked with blobs before).
如果它改变了答案，我知道所有的 blob 都是 .bmp 图像（以前从未使用过 blob）。
回答by Vincent Malgrat
lengthand dbms_lob.getlengthreturn the number of characters when applied to a CLOB(Character LOB). When applied to a BLOB(Binary LOB), dbms_lob.getlengthwill return the number of bytes, which may differ from the number of characters in a multi-byte character set.
length并dbms_lob.getlength返回应用于CLOB（字符 LOB）时的字符数。当应用于BLOB（二进制 LOB）时，dbms_lob.getlength将返回字节数，这可能与多字节字符集中的字符数不同。
As the documentation doesn't specify what happens when you apply lengthon a BLOB, I would advise against using it in that case. If you want the number of bytes in a BLOB, use dbms_lob.getlength.
由于文档没有具体说明申请lengthBLOB时会发生什么，我建议不要在这种情况下使用它。如果您想要 BLOB 中的字节数，请使用dbms_lob.getlength.
