SQL Server(2)

1. Create modification table ( Do not delete the original table , Make changes )

Add new column ：alter table tb_student add Gender bit null
Delete old columns ：alter table tb_student drop column Gender
Change column names ：alter table tb_student alter column Gender bit null
Change column names ： exec sp_rename 'tb_student.ClassNo','No','Column'

2. Create constraints

( Do not delete the original table , Create constraints )
alter table Table name add constraint PK_tb_student primary key ( Name )
alter table Table name add constraint FK_ Table name foreign key ( Name 1) references surface 2 name ( Name 2)
alter table Table name add constraint UK_ Table name _ Name unique（ Name 1, Name 2）
alter table Table name add constraint CK_ Table name _ Name check( Conditional expression )
alter table Table name add constraint DK_ Table name default（0）for Name

3. insert data

A single piece of data is listed
insert （into） Table name （ Name 1, Name 2）values ( value 1, value 2,...)
insert （into） Table name （ Name 1, Name 2）select value 1, value 2....
union（ be used for select Concatenation of insert statements ）union all Allowing repetition is efficient
Multiple data listed
insert （into） Table name （ Name 1, Name 2）values ( value 1, value 2,...),( value 3, value 4,...),( value 5, value 6,...)
Clone data ( Copy data from one table to another )
1）：insert Target table （ Name 1）select Name 2 from The original table
2）：select Name 2 into surface 1 from surface 2

4. Update data

update Table name set Name 1= value where Name 2= value
( If not where Words , The data of the whole table has been modified )

5. Delete data

1）：delete from Table name where Name = value
（ Cause the value of the identification column to be discontinuous ）
2）：truncate table Table name （ Table data is cleared , Restore to initialization , The identity column is also restored ）
truncate Efficient than delete high ,delete No data is deleted , Will be recorded in the log ,
,truncate No logging , Do not activate the trigger ,drop truncate It's instant operation
author ： Late boat •

Game programming , A game development favorite ~

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