SQL DATA

Find Top Value In a Table Column

create table ctr

(

num  int

 )

insert into ctr values(1)

insert into ctr values(2)

insert into ctr values(3)

insert into ctr values(4)

insert into ctr values(5)

insert into ctr values(33)

insert into ctr valuse(63)

select top 1 num from(select top 3 num from ctr  order by num desc) ctr order by num desc

OutPut Is 63

Add New Column In the Table

alter table table_name add column_name datatypewithsize

Mdify Column In the Table

alter table table_name alter  column column_name datatypewithsize

Create Sub Table Use The An Other Table

select columns_names into new_Table_Name from Old_Table_Name

Create Table Using Constraints

create table emp

(

id int primary key,

name varchar(10) null,

city varchar(10) check(city in('ORAI','BHOPAL'))

)

create table dept

(

d_id int primary key,

e_id int references emp(id),

d_name varchar(30) not null

)

If You Want To Add Constraint After Create Table

create table emp

(

id int ,

name varchar(10),

city varchar(10) )

create table dept

(

d_id int,

e_id int,

d_name varchar(30)

)

Follow Some Point :::

1- If we Want to add the primary key in the column than first add the not null constraint  in the table tha after add  the primary key.....

Syntax is :::

              alter table emp1 alter column  id  int  not null

              alter table emp1 add constraint  i  primary key(id)i ==  Is Constraint Name


2-Add the foreign key in the table than follow this

Syntax :::
      alter table dept1 add constraint ii  foreign key(e_id)  references emp1(id)

ii ==  Is Constraint Name       

3- add the check consteaint
    table emp1 add constraint iiii check(city in('orai','kanpur'))
iiii ==  Is Constraint Name       

Some Other Quries  

create datebase database_name

use database database_name

drop table table_name

truncae table table_name

delete from  table_name

drop command drop the stracture but truncate command delete the table data

alter