/*推断表AA中是否存在AA_ID这一列。假设不存在，则新增*/ IF NOT EXISTS (SELECT 1 FROM syscolumns INNER JOIN sysobjects ON sysobjects.id = syscolumns.id WHERE syscolumns.name = 'AA_ID' AND sysobjects.name = 'AA') ALTER TABLE AA ADD AA_ID VARCHAR(30) NULL GO
原文：http://www.cnblogs.com/clnchanpin/p/7047589.html