好的,所以Sybase(12.5.4)将允许我执行以下操作来删除表(如果该表已经存在):
OK, so Sybase (12.5.4) will let me do the following to DROP a table if it already exists:
IF EXISTS ( SELECT 1 FROM sysobjects WHERE name = 'a_table' AND type = 'U' ) DROP TABLE a_table GO但是如果我尝试对表创建进行同样的操作,我总是会被警告table已经存在,因为它继续进行并试图创建我的表并忽略了条件语句。只需尝试运行以下语句两次,您就会明白我的意思了:
But if I try to do the same with table creation, I always get warned that the table already exists, because it went ahead and tried to create my table and ignored the conditional statement. Just try running the following statement twice, you'll see what I mean:
IF NOT EXISTS ( SELECT 1 FROM sysobjects WHERE name = 'a_table' AND type = 'U' ) CREATE TABLE a_table ( col1 int not null, col2 int null ) GO运行以上命令会产生以下结果错误:
Running the above produces the following error:
(本地主机)上的SQL Server错误错误:2714,行:7消息:有在数据库中已经是一个名为 a_table的对象。
该怎么办? ?!
推荐答案到目前为止,我唯一想到的解决方法是使用立即执行:
The only workaround I've come up with so far is to use execute immediate:
IF NOT EXISTS ( SELECT 1 FROM sysobjects WHERE name = 'a_table' AND type = 'U' ) EXECUTE("CREATE TABLE a_table ( col1 int not null, col2 int null )") GO工作就像一种魅力,感觉就像肮脏的骇客。
works like a charm, feels like a dirty hack.
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如何有条件地在Sybase(TSQL)中创建表?
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