What is the actual difference between "CREATE DATABASE database_name" and "CREATE DATABASE IF NOT EXISTS database_name"?
2条回答 默认 最新
- doukezi4606 2015-10-04 22:05关注
CREATE DATABASE IF NOT EXISTS database_name
will execute theCREATE DATABASE database_name
only if thedatabase_name
does not already exist.If the
database_name
does not exit, both queries will do the same job, that is they create thedatabase_name
.If the
database_name
exits,CREATE DATABASE database_name
will return an error similar to "the database 'database_name' already exists", whileCREATE DATABASE IF NOT EXISTS database_name
will not return an error (it simply does nothing).When you write a script (let's say you create the database, then create tables, then insert some data), you don't want the execution to stop just because the database exits, so you use the second query.
本回答被题主选为最佳回答 , 对您是否有帮助呢?解决 无用评论 打赏 举报
悬赏问题
- ¥15 数据库数据成问号了,前台查询正常,数据库查询是?号
- ¥15 算法使用了tf-idf,用手肘图确定k值确定不了,第四轮廓系数又太小才有0.006088746097507285,如何解决?(相关搜索:数据处理)
- ¥15 彩灯控制电路,会的加我QQ1482956179
- ¥200 相机拍直接转存到电脑上 立拍立穿无线局域网传
- ¥15 (关键词-电路设计)
- ¥15 如何解决MIPS计算是否溢出
- ¥15 vue中我代理了iframe,iframe却走的是路由,没有显示该显示的网站,这个该如何处理
- ¥15 操作系统相关算法中while();的含义
- ¥15 CNVcaller安装后无法找到文件
- ¥15 visual studio2022中文乱码无法解决