However, I don't want to drop the entire database (because then I'd have to re-run the create script), nor do I want to delete all the tables in it (there is one table that needs to remain).In case it's of use to anyone, or I need to do this again, here's a snippet ...
it deletes the entire records as well as the schema and structure of the table along with its named elements. The DROP command is a Data Definition Language (DDL) command. In addition, this command can also be used to drop databases. Databases or tables once dropped are wiped out of exis...
Multiple tables can be dropped in the sameDROP TABLEstatement. If both the referencing table in aFOREIGN KEYconstraint and the table with the referenced primary or unique key are being dropped in the sameDROP TABLEstatement, the referencing table must be listed first. ...
Multiple tables can be dropped in any database. If a table being dropped references the primary key of another table that is also being dropped, the referencing table with the foreign key must be listed before the table holding the primary key that is being referenced. When a table is dropp...
一、DROP 1、DROP CATALOG 2、DROP DATABASE 3、DROP TABLE 4、DROP VIEW 5、DROP FUNCTION 6、drop table示例 二、alter 1、ALTER DATABASE 2、ALTER TABLE 1)、建表 2)、ADD 1、增加单列示例 2、增加watermark列 3)、MODIFY 1、修改列 2、修改水印 4)、DROP 5)、RENAME 6)、SET 7)、RESET 3、AL...
Created_tmp_disk_tables:创建内部磁盘临时表的数量; Created_tmp_tables:创建内部临时表的数量; Start/End:语句开始和结束时间 Tips:在MariaDB中,可以开启log_slow_verbosity参数,可以更加详尽的打印出慢SQL的执行细节,该参数在MySQL8.0版本中并未支持,读者感兴趣可以自行查阅相关信息。
5. Not using temporary tables for complex queries SQL would be great if only we could debug queries. What if I told you can debug them! You can breakdown a complex query and create multiple temporary tables. Then you can run “sanity check” queries against those tables to make sure they...
1>.drop drop是DDL,会隐式提交,所以,不能回滚,不会触发触发器。 drop语句删除表结构及所有数据,并将表所占用的空间全部释放。 drop语句将删除表的结构所依赖的约束,触发器,索引,依赖于该表的存储过程/函数将保留,但是变为invalid状态。 相关笔记请参考:https://www.cnblogs.com/yinzhengjie/p/10331914.html。
课程比较简单,分成四个部分:Manipulation,Queries,Aggregate Functions,和Multiple Tables. 比如第一部分Manipulation,点进去之后可以看到: 左边是理论介绍,中间可以输入命令,输入完了点击运行,在后边就可以看到结果。 课程分成很多小练习,按照这些练习一步步做下去就完成整个课程。 比如第一部分地第二页是这样的: 第三页...
DROP(DATABASE|SCHEMA)[IFEXISTS]database_name[RESTRICT|CASCADE]; 如果数据库下有表,则不允许删除;如果要删除,后面加 CASCADE。RESTRICT 为默认值,默认不允许删除。 例子 代码语言:javascript 代码运行次数:0 运行 AI代码解释 drop databaseifexists myhive;drop databaseifexists myhive cascade; ...