一、区别和定义
LONG: 可变长的字符串数据,最长2G,LONG具有VARCHAR2列的特性,可以存储长文本一个表中最多一个LONG列
LONG RAW: 可变长二进制数据,最长2G
CLOB: 字符大对象Clob 用来存储单字节的字符数据
NCLOB: 用来存储多字节的字符数据
BLOB: 用于存储二进制数据
BFILE: 存储在文件中的二进制数据,这个文件中的数据只能被只读访。但该文件不包含在数据库内。
bfile字段实际的文件存储在文件系统中,字段中存储的是文件定位指针.bfile对oracle来说是只读的,也不参与事务性控制和数据恢复.
CLOB,NCLOB,BLOB都是内部的LOB(Large Object)类型,最长4G,没有LONG只能有一列的限制
要保存图片、文本文件、Word文件各自最好用哪种数据类型?
--BLOB最好,LONG RAW也不错,但Long是oracle将要废弃的类型,因此建议用BLOB。
二、操作
1、 get
CLOB
java 代码
-
- Connection con = ConnectionFactory.getConnection();
- con.setAutoCommit(false);
- Statement st = con.createStatement();
-
- ResultSet rs = st.executeQuery("select CLOBATTR from TESTCLOB where ID=1");
- if (rs.next())
- {
- java.sql.Clob clob = rs.getClob("CLOBATTR");
- Reader inStream = clob.getCharacterStream();
- char[] c = new char[(int) clob.length()];
- inStream.read(c);
-
- data = new String(c);
- inStream.close();
- }
- inStream.close();
- con.commit();
- con.close();
-
BLOB
java 代码
-
- Connection con = ConnectionFactory.getConnection();
- con.setAutoCommit(false);
- Statement st = con.createStatement();
-
- ResultSet rs = st.executeQuery("select BLOBATTR from TESTBLOB where ID=1");
- if (rs.next())
- {
- java.sql.Blob blob = rs.getBlob("BLOBATTR");
- InputStream inStream = blob.getBinaryStream();
-
- data = new byte[input.available()];
- inStream.read(data);
- inStream.close();
- }
- inStream.close();
- con.commit();
- con.close();
2、 put
CLOB
java 代码
-
- Connection con = ConnectionFactory.getConnection();
- con.setAutoCommit(false);
- Statement st = con.createStatement();
-
- st.executeUpdate("insert into TESTCLOB (ID, NAME, CLOBATTR) values (1, "thename", empty_clob())");
-
- ResultSet rs = st.executeQuery("select CLOBATTR from TESTCLOB where ID=1 for update");
- if (rs.next())
- {
-
- oracle.sql.CLOB clob = (oracle.sql.CLOB) rs.getClob("CLOBATTR");
- Writer outStream = clob.getCharacterOutputStream();
-
- char[] c = data.toCharArray();
- outStream.write(c, 0, c.length);
- }
- outStream.flush();
- outStream.close();
- con.commit();
- con.close();
-
BLOB
java 代码
-
- Connection con = ConnectionFactory.getConnection();
- con.setAutoCommit(false);
- Statement st = con.createStatement();
-
- st.executeUpdate("insert into TESTBLOB (ID, NAME, BLOBATTR) values (1, "thename", empty_blob())");
-
- ResultSet rs = st.executeQuery("select BLOBATTR from TESTBLOB where ID=1 for update");
- if (rs.next())
- {
-
- oracle.sql.BLOB blob = (oracle.sql.BLOB) rs.getBlob("BLOBATTR");
- OutputStream outStream = blob.getBinaryOutputStream();
-
- outStream.write(data, 0, data.length);
- }
- outStream.flush();
- outStream.close();
- con.commit();
- con.close();
posted on 2010-08-06 14:20
fly 阅读(899)
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