oracle 如何在表格中找到长列的长度
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how to find length of a Long Column in a table
提问by Egalitarian
I have a LONG column named FileSize in a table called Files.
我在名为 Files 的表中有一个名为 FileSize 的 LONG 列。
To achieve the objective, I did the following :
为了实现目标，我做了以下工作：
I wrote this PL/SQL script to find the size
我写了这个 PL/SQL 脚本来查找大小
declare
long_var LONG:=0;
begin
dbms_output.put_line(length(long_var));
execute immediate 'SELECT FILESIZE INTO long_var FROM FILES';
dbms_output.put_line(length(long_var));
end;
But it throws an error :
但它抛出一个错误：
ORA-00905: missing keyword
ORA-06512: at line 5
I was doing the following as I saw thw following on the link given below: http://www.techonthenet.com/oracle/questions/long_length.php
当我在下面给出的链接上看到以下内容时，我正在执行以下操作：http: //www.techonthenet.com/oracle/questions/long_length.php
Can some one suggest what I am doing wrong as I can not identify the key word I am missing
有人可以建议我做错了什么，因为我无法确定我遗漏的关键字
Thanks.
谢谢。
回答by
You don't need EXECUTE IMMEDIATE in this context.
在这种情况下，您不需要 EXECUTE IMMEDIATE。
DECLARE
long_var long:=0;
BEGIN
DBMS_OUTPUT.PUT_LINE(LENGTH(long_var));
SELECT filesize INTO long_var FROM files;
DBMS_OUTPUT.PUT_LINE(LENGTH(long_var));
END;
/
EXECUTE IMMEDIATE runs a stand alone statement of SQL from your PL/SQL code. It can't return anything to your code. The statement you're using isn't valid SQL so you get the ORA-00905. It is valid PL/SQL code and so works as you'd expect once EXECUTE IMMEDIATE is removed.
EXECUTE IMMEDIATE 从您的 PL/SQL 代码运行一个独立的 SQL 语句。它无法向您的代码返回任何内容。您使用的语句不是有效的 SQL，因此您得到 ORA-00905。它是有效的 PL/SQL 代码，因此一旦 EXECUTE IMMEDIATE 被删除，它就会像您期望的那样工作。
Edit
编辑
Code for your follow on question: To do this with more than one row you can use this
您的后续问题的代码：要使用多行执行此操作，您可以使用它
DECLARE
CURSOR C1 IS
SELECT filesize FROM files;
BEGIN
FOR files IN c1
LOOP
DBMS_OUTPUT.PUT_LINE(LENGTH(files.filesize));
END LOOP;
END;
/
