Select query inside PL/SQL block.

Question

Hello Experts,
I am just a beginner with PL/SQL.
If I write a select query from client like SQL dev and fire it against a database, it gives me result.
Eg: select * from employee;
Now when I use the same Query inside a PL/SQL block suppose:
Declare
begin
select * from employee;
end;
This gives error on execution, mentioning that an INTO is expected etc...
I have doubts here:
1. Can't I use a plain select inside a PL/SQL block (if so why?)
I know this is kind of very basic question, I tried searching this on the forum but could not find the thread, please redirect me to the link if this is already answered.

Answer 1

user8578271 wrote:
Hello Experts,
I am just a beginner with PL/SQL.
If I write a select query from client like SQL dev and fire it against a database, it gives me result.
Eg: select * from employee;
Now when I use the same Query inside a PL/SQL block suppose:
Declare
begin
select * from employee;
end;
This gives error on execution, mentioning that an INTO is expected etc...
I have doubts here:
1. Can't I use a plain select inside a PL/SQL block (if so why?) Because when you run a query in a tool like SQL Developer, or SQL*Plus or TOAD etc. then it opens up a cursor and fetches the data into internal memory structures before displaying it, and that is all done automatically and hidden from you. In PL/SQL, there is no interface to display the results of SQL queries, so you have to specifically tell it what to put the data into.
The syntax is (in basic terms)...
SELECT column1, column2... columnX
INTO variables or record structure
FROM ...Though that can only select a single row of data. If your query returns more than 1 row it will give a TOO_MANY_ROWS exception. If your query returns no rows you will get a NO_DATA_FOUND exception.
If you need to select multiple rows into variables etc., then you would need to "BULK COLLECT" into a collection/array structure, though this takes up valuable memory on the server and shouldn't be used unless necessary (and you understand the implications of doing it).