本文介绍了如何有条件地在 Sybase (TSQL) 中创建表?的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
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 GOBut 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 ) GORunning the above produces the following error:
SQL Server Error on (localhost) Error:2714 at Line:7 Message:There is already an object named 'a_table' in the database.
What's the deal with that?!
解决方案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 )") GOworks 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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