Incrementing values in table using PL/SQL? - sql

Question

In my query I'm using a for loop, which displays 1000 three times. I have to increment 1000 for each iteration of the loop, i.e. 1001, 1002,.. same number three times i.e. I want to add into my table 1000,1000,1000,1001,1001,1001 and 1002,1002,1002,
declare
CPName varchar(20) :=1000;
a number;
begin
for a in 1 .. 3 loop
insert into clients values (CPName,null,null);
end loop;
end;
How can I do this?

Answer 1

CPName is a VARCHAR; I assume you want this to be a number, in which case you just add it on.
There's no need to define the variable a either, it's implicitly declared by the LOOP. I would call this i as it's a more common name for an index variable.
declare
CPName integer := 1000;
begin
for i in 1 .. 3 loop
insert into clients values (CPName + i, null, null);
end loop;
end;
You can do this all in a single SQL statement though; there's no need to use PL/SQL.
insert into clients
select 1000 + i, null, null
from dual
cross join ( select level as i
from dual
connect by level <= 3 )
Based on your comments you actually want something like this:
insert into clients
with multiply as (
select level - 1 as i
from dual
connect by level <= 3
)
select 1000 + m.i, null, null
from dual
cross join multiply m
cross join multiply
This will only work if you want the same number of records as you want to increase so maybe you'd prefer to do it this way, which will give you a lot more flexibility:
insert into clients
with increments as (
select level - 1 as i
from dual
connect by level <= 5
)
, iterations as (
select level as j
from dual
connect by level <= 3
)
select 1000 + m.i, null, null
from dual
cross join increments m
cross join iterations
Using your LOOP methodology this would involve a second, interior loop:
declare
CPName integer := 1000;
begin
for i in 1 .. 3 loop
for j in 1 .. 3 loop
insert into clients values (CPName + i, null, null);
end loop;
end loop;
end;