程序里不认clob类型，有可能是data provider的问题，你的data provider可能是 Provider=MSDAORA.1，而微软的provider for oracle 不支持CLOb类型，你可试试 Provider=OraOLEDB.Oracle.1
blob 类型的长度是多少在oracle中？
CLOB A character large object containing single-byte characters. Both fixed-width and variable-width character sets are supported, both using the CHAR database character set. Maximum size is 4 gigabytes.
BLOB A binary large object. Maximum size is 4 gigabytes.VARCHAR2(size) [BYTE | CHAR] Variable-length character string having maximum length size bytes or characters. Maximum size is 4000 bytes, and minimum is 1 byte or 1 character. You must specify size for VARCHAR2. BYTE indicates that the column will have byte length semantics; CHAR indicates that the column will have character semantics.
Provider=MSDAORA.1，而微软的provider for oracle 不支持CLOb类型，你可试试
Provider=OraOLEDB.Oracle.1
A character large object containing single-byte characters. Both fixed-width and variable-width character sets are supported, both using the CHAR database character set. Maximum size is 4 gigabytes.
BLOB
A binary large object. Maximum size is 4 gigabytes.VARCHAR2(size) [BYTE | CHAR]
Variable-length character string having maximum length size bytes or characters. Maximum size is 4000 bytes, and minimum is 1 byte or 1 character. You must specify size for VARCHAR2.
BYTE indicates that the column will have byte length semantics; CHAR indicates that the column will have character semantics.
oracle安装后有相关的例子，微软的开发工具最后使用Oracle提供的0040技术。