有一个名为utl_raw.cast_to_raw(vc)的函数，该函数将varchar2转换为BLOB值.

there is a function called utl_raw.cast_to_raw(vc) which transforms a varchar2 into a BLOB value.

但是，我建议使用CLOB来存储字符串值. BLOB完全没有字符语义，即NLS_LANG设置被忽略.

However, I recommend to use CLOB to store string values. BLOB has no character semantics at all, i.e., NLS_LANG settings are ignored.

如果要将VARCHAR2转换为CLOB，只需使用TO_CLOB

if you want to transform VARCHAR2 to CLOB, simply use TO_CLOB