表的截断，删除和删除有什么区别？何时选择哪个？

Question

表格的truncate,drop和delete有什么区别？何时选择哪个？有没有人有一个快速的比较？我已经看到了很多关于这方面的信息，但还没有在清晰的概述中找到它。我希望这篇文章有助于理解。

我的意思是像在T-SQL这些语句中使用：

truncate table TableX 
drop table TableX 
delete table_name 

Answer 1

基于由@Michal here答案，多一些搜索我做了下面的语句下面的对比（在T-SQL ）：truncate table TableX，drop table TableX和delete table_name。

      Truncate   Drop     Delete 
Speed      [Fast]    Slow     Slowest 
Rolback possibility  No     No     [Yes] 
Specifiable conditions  No     No     [Yes] 
Scope      All records  All record+Headers Some records/All records 
               =whole table 
Cascading effects   No*    No*     [Yes]** 



**For example: in a Table_1 there is a PK, in Table_2 there is a FK that relates with 
the PK of Table_1, other words there is referential integrity. If the PK has `'ON DELETE CASCADE'` 
and `delete Table_1` is ordered, then the data in Table_2 will be deleted too, 
automatically. For more info about ON DELETE CASCADE and ON ALTER CASCADE, see: 
https://technet.microsoft.com/en-us/library/ms186973%28v=sql.105%29.aspx. 

Cascading does automatic alterations and deletes of depending objects such as foreign keys (FK), 
views, and triggers. Sometimes very useful, sometimes very dangerous.. 

*The drop and truncate statements of a Table_1 (with PK and FK in Table_2, as decribed 
in **) can't be executed, because the ssdms prohibits that. To accomplish the truncation 
or dropping of a Table_1: first get rid of the FK in Table_2, by altering the table design, or 
by dropping table2. 

看到比较基础的决定时所使用的语句...

作为一个拇指：

If you want to get rid of only records：当需要一个条件删除 使用删除，使用截断当所有记录可能会被删除。当你想能够回滚然后使用删除。

If you want to get rid of the whole table，包括标题（带有设置的列），然后选择放置。

If you want to get rid of values and automatically the related objects（并且表中定义了级联），使用delete。 （PS：在其他方言中，即使当表没有设计级联时，似乎也有办法实现它，但据我所知t-sql/msss中没有;但如果我错了，请纠正我）

PS：如果你想alter or delete的preferences of a column，然后（在T-SQL方言）使用方法：

阿尔特：

alter table tableX 
alter columnX datatypeX 

删除：

alter table tableX 
drop column columnX 

---

--And here's some code to play with 
--table to truncate, drop or delete 

create table TableX(
     [Name] [nchar](25) null, 
     [ID_Number] [int] not null) 


--tables with PK and FK 
create table Table_1(
     [Name] [nchar](25) null, 
     [ID_Number] [int] not null primary key) 

create table Table_2(
     [ID_Number] int not null foreign key references Table_1(ID_Number) on delete cascade, 
     [Buys] [int] null) 

--the on delete cascade make it happen that when a ID_Number is Table_1 is deleted, that row 
is automatically deleted in Table_2 too. But not the other way around, 
therefor alter the design of Table_1. 

insert into Table_1 (Name,ID_Number) values ('A',1),('B',2),('C',3); 
insert into Table_2 (ID_Number,Buys) values (1,10),(2,20),(3,30); 

select * from Table_1 
select * from Table_2 

truncate table table_2 
truncate table table_1 

drop table table_2 
drop table table_1 

delete Table_1 

delete from dbo.table_1 where name='A' 
delete from Table_1 where name like '%' 
delete from dbo.table_2 where ID_Number=2