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Question

我有一个包含数据类型列的表LONG RAW.如何确定此列中数据的大小(以字节为单位)？

如果我调用LENGTH它上面的函数,它就会升起ORA-00932: inconsistent datatypes: expected NUMBER got LONG BINARY.

万一你认为:UTL_RAW.LENGTH加注ORA-00997: illegal use of LONG datatype:)

(是的,我知道LONG RAW已被弃用 - 由于一些可能需要它的旧软件而出现了问题)

Answer 1

我不认为在PLSQL中操纵超过32k的LONG RAW是可能的.这是一个返回LONG RAW长度的java过程.

首先,设置:

SQL> CREATE TABLE my_table (ID NUMBER, my_long_raw_column LONG RAW);

Table created

SQL> INSERT INTO my_table VALUES (1, utl_raw.cast_to_raw('123456789'));

1 row inserted

java类(我的java有点生疏):

SQL> CREATE OR REPLACE AND COMPILE JAVA SOURCE NAMED "Raw" AS
  2  import java.io.*;
  3  import java.sql.*;
  4  import oracle.jdbc.driver.*;
  5  
  6  public class Raw {
  7  
  8     public static int getLength(int pk) throws SQLException,IOException {
  9  
 10        Connection conn = new OracleDriver().defaultConnection();
 11  
 12        PreparedStatement ps = conn.prepareStatement
 13           ( "SELECT my_long_raw_column FROM my_table WHERE id = ?" );
 14        ps.setInt( 1, pk);
 15        ResultSet rs = ps.executeQuery();
 16  
 17        int len = 0;
 18        if (rs.next()) {
 19           InputStream is = rs.getBinaryStream(1);
 20           int nb = is.read(new byte[1024]);
 21           while (nb>0) {
 22              len += nb;
 23              nb = is.read(new byte[1024]);
 24           }
 25        } else
 26           len = -1;
 27  
 28        rs.close();
 29        ps.close();
 30
 31        return len;
 32     }
 33  }
 34  /

Java created

我们称之为:

SQL> CREATE OR REPLACE
  2  FUNCTION get_lr_length(p_id NUMBER) RETURN NUMBER
  3  AS LANGUAGE JAVA
  4  NAME 'Raw.getLength(int) return int';
  5  /

Function created

SQL> select get_lr_length(id) from my_table;

GET_LR_LENGTH(ID)
-----------------
                9

我已经测试了大于32k字段的功能,它似乎工作.