删除DB2表（如果存在） [英] Drop DB2 table if exists

问题描述

在我的脚本中，我必须对联接表进行大量选择，因此我决定将这种联接放入临时表中。

In my script I have to do a lot of selects to a joined table, so instead I decided to put this join into a temporal table.

首先我想：

1. Create table
2. Put the data from the join into a table
3. Drop the table 

但是后来我想到，如果脚本在删除表之前失败了怎么办？

But then I thought, what if the script fails before I dropped the table?

所以我决定去：

1. Drop the table
2. Create the table
3. Put the data from the join into a table

我不介意在下次运行脚本之前是否将表保留在那里，因此第二个选项也适用。

I don't really mind if the table is left there until the next time I run the script, so the second option works too.

但是如果有人已经放下桌子怎么办？

But what if somebody had already dropped the table?

我看到某些系统存在 drop if if，但不幸的是没有DB2。我想要做的事情不会使脚本在放置表失败时消失。

I saw some systems have a "drop if exists" but unfortunately not DB2. I would like to do something that won't make the script die when the drop table fails.

想法？在任何一个？谢谢！

Ideas? On any of this? Thanks!

编辑：我忘了说这是在PERL脚本中！

I forgot to say this is in a PERL script!

推荐答案

最好的方法是使用匿名块，例如代码

The best way to do this is by using an annonymous block like in this code

您需要在动态sql中调用放置表，并在块中捕获异常。

You need to call the drop table in a dynamic sql, and catch the exception in the block.

--#SET TERMINATOR @
begin
  declare statement varchar(128);
  declare continue handle for sqlstate '42710' BEGIN END;
  SET STATEMENT = 'DROP TABLE MYTABLE';
  EXECUTE IMMEDIATE STATEMENT;
end @

此代码将在DB2中正常运行。它不必是过程或函数的一部分。

This code will run normally in DB2. It does not need to be part of a procedure nor function.

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