数据库可以判断某一列二进制是否为空吗？

Question

就像判断字符串似的 select * from articles where sexs is not null;
类似上面条件二进制有吗？ 

Answer 1

同样可以 IS NULL 啊。楼主的问题具体是什么？ 那就举例说明。

Answer 2

我也不知道为什么，我插入一个null，数据库自动变成0000，为什么呢？

Answer 3

show create table articles ; 贴出来。是不是有默认值啊？ 或者有没有触发器？

Answer 4

你的建表语句是什么，检查一下是否有DEFAULT值 OR TRIGGER

Answer 5

我往oracle数据库里插入2进制文件，直接insert语句是无法插进去
后来网上找了找资料，说需要3步：1.插入一个空，2.查询出来二禁止，3.往里面赋值。。public void insertTraitStrTrees(List<TraitStrTrees> list, String tableName) {        connect();
        sql = "insert into " + tableName + " values (?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?)";
        System.out.println(sql);
        try {
            conn.setAutoCommit(false);
            int isCommit = 0;
            for (int i = 0; i < list.size(); i++) {
                isCommit++;
                ps = conn.prepareStatement(sql);
                ps.setInt(1, list.get(i).getDg_id());
                ps.setInt(2, list.get(i).getId());
                ps.setString(3, list.get(i).getTrait_value());
                ps.setInt(4, list.get(i).getParent_id());
                ps.setInt(5, list.get(i).getChild_id());
                ps.setInt(6, list.get(i).getLeft_id());
                ps.setInt(7, list.get(i).getRight_id());                ps.setBlob(8, BLOB.getEmptyBLOB());
                ps.setBlob(9, BLOB.getEmptyBLOB());
                ps.setBlob(10, BLOB.getEmptyBLOB());
                ps.setBlob(11, BLOB.getEmptyBLOB());
                ps.setBlob(12, BLOB.getEmptyBLOB());
                ps.setBlob(13, BLOB.getEmptyBLOB());
                ps.setBlob(14, BLOB.getEmptyBLOB());                ps.setInt(15, list.get(i).isFrist());
                ps.setInt(16, list.get(i).isHasChild());
                ps.executeUpdate();
                //ps.close();
                String sql1 = "select articles,pictures,tables,videos,audios,ads,pages from " + tableName + " where dg_id=" + list.get(i).getDg_id() + " and id=" + list.get(i).getId() + " FOR UPDATE";
                ps = conn.prepareStatement(sql1);                ResultSet rs = ps.executeQuery();
                rs.next();
                BLOB articles = (BLOB) rs.getBlob(1);
                BLOB pictures = (BLOB) rs.getBlob(2);
                BLOB tables = (BLOB) rs.getBlob(3);
                BLOB videos = (BLOB) rs.getBlob(4);
                BLOB audios = (BLOB) rs.getBlob(5);
                BLOB ads = (BLOB) rs.getBlob(6);
                BLOB pages = (BLOB) rs.getBlob(7);                OutputStream out1 = articles.getBinaryOutputStream();
                OutputStream out2 = pictures.getBinaryOutputStream();
                OutputStream out3 = tables.getBinaryOutputStream();
                OutputStream out4 = videos.getBinaryOutputStream();
                OutputStream out5 = audios.getBinaryOutputStream();
                OutputStream out6 = ads.getBinaryOutputStream();
                OutputStream out7 = pages.getBinaryOutputStream();
                try {
                    out1.write(list.get(i).getArticles());
                    out1.close();
                    out2.write(list.get(i).getPictures());
                    out2.close();
                    out3.write(list.get(i).getTables());
                    out3.close();
                    out4.write(list.get(i).getVideos());
                    out4.close();
                    out5.write(list.get(i).getAudios());
                    out5.close();
                    out6.write(list.get(i).getAds());
                    out6.close();
                    out7.write(list.get(i).getPages());
                    out7.close();
                } catch (IOException ex) {
                    Logger.getLogger(MysqlDB.class.getName()).log(Level.SEVERE, null, ex);
                }                String sql2 = "update " + tableName + " set articles=? , pictures=? , tables=? , videos=? , audios=? , ads=? , pages=? where dg_id=" + list.get(i).getDg_id() + " and id=" + list.get(i).getId();
                ps = conn.prepareStatement(sql2);
                ps.setBlob(1, articles);
                ps.setBlob(2, pictures);
                ps.setBlob(3, tables);
                ps.setBlob(4, videos);
                ps.setBlob(5, audios);
                ps.setBlob(6, ads);
                ps.setBlob(7, pages);                ps.executeUpdate();
                ps.addBatch();
                if (isCommit % 50 == 0) {
                    ps.executeBatch();
                    conn.commit();
                    ps.close();
                    close();
                    connect();
                } else if (i == list.size() - 1) {
                    ps.executeBatch();
                    conn.commit();
                    ps.close();
                    close();
                }
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            close();
        }    }

Answer 6

大哥，你又不贴create语句，insert也没有字段名，谁知道哪个语句对应sexs字段
另外，你前N个PreparedStatement都没有关闭，也许不会引起大问题，但是这终究不是一个好习惯！！！