random

Repeat practice practice practice

using System;
public Static class NullUtil
{
	public static bool IsNull(this object x)
	{
	
	return x == null;
	}
}
public class Test 
{
	static void Main()
	{
	object y = null;
	Console.writeLine(y.IsNull());
	y= new object();
	Console.WriteLine(y.IsNull());
	}
}

1-1

create table squeezable(random_text varchar2(50))
/
declare

i	binary_integer;
j	binary_integer;
l	binary_integer;
v_string varchar2(50);
begin
for i in 1 .. 10000
loop
j :=dbms_random.value(1,100);
v_string :=dbms_random.string('U',50);
while(j<length(v_string))
loop
k :=dbms_random.value(1,3);
v_string :=substr(substr(v_string,1,j)||rpad('',k)
||substr(v_string,j+1),1,50);
j :=dbms_random.value(1,100);
end loop;
insert into squeezable
values(v_string);
end loop;
commit;
end;
/

1-2

update accounts
set balance = balance - purchased_amount
where balance >= purchased_amount
and credit_limit >= purchased_amount
and expiry_date > today()
and customer_id = provided_id
and card_num = provided_cardnum

select c.customer_id,a.card_num,a.expiry_date,
a.credit_limit,a.balance
from customers c
left outer join accounts a
on a.customer_id = c.customer_id
and a.card_num = provided_cardnum
where c.customer_id = provied_id


​```SQL
select custname
from customers
where city ='GOTHAM'
and custid in
(select o.custid
from orders o,
(select distinct od.ordid from orderdetail od,
articles a
where a.artname='BATMOBILE'
and a.artid = od.artid)x
where o.ordered >= somefunc
and x.ordid = o.ordid)

INSERT INFO your_table(column_namel,column_name2,...)
	VALUES('value1','value2',...)
	
1-1
INSERT INTO my_contacts
(last_name,first_name,email,gender,birthday,professional,location,status,interests,seeking)
VALUES
('Anderson','Jillian','jill_anderson@breakneckpizza.com','F','1980-09-05','Technical Writer','PaloAlto,CA', 'Single','Kayaking, Reptiles','Relationship,Friends');

1-2
var query = from user in SampleData.AllUsers
			from project in SampleData.AllProjects
			select new { User = user,Project = project};
foreach (var pair in query)
{
	Console.WriteLine("{0}/{1}",
					pair.User.Name,
					pair.Project.Name)
}

1-3
var query = from defect in SampleData.AllDefects
			where defect.AssignedTo != null
			group defect by defect.AssignedTo;
			
foreach (var entry in query)
{
	Console.WriteLine(entry.Key.Name);
	foreach (var defect in entry)
	{
		Console.WriteLine(" ({0}) {1}",
						defect.Severity, defect.Summary);
	}
	Console.WriteLine();
}