SQL小结（四）

数据库还可以储存大对象——图片或其他数据，二进制大对象为BOLB,字符型大对象为CLOB，以下为获取图像：

PreparedStatement stat = conn.prepareStatement("SELECT Cover FROM BookCovers WHERE ISBN =?");
stat.set(1.isbn);
ResultSet result = stat.executeQuery();
if(result.next()){
Blob coverBlob = result.getBlob(1);
Image coverImage = ImageIO.read(coverBlob.getBinaryStream());
}//CLOB调用getSubString或getCharacterStream方法

将该对象存储到数据库中:

Blob coverBlob = connection.createBlob();
in offset = 0;
OutputStream out = coverBlob.setBinaryStream(offset);
ImageIO.write(coverImage, "PNG", out);
PreparedStatement stat = conn.prepareStatement("INSERT INTO Cover VALUES (?, ?)");