I'm trying to learn PL/SQL by simply assigning a variable from a select statement and then, to confirm it's working, print it sql output.
DECLARE ALLOW_STUFF NUMBER;
BEGIN
SELECT VAL_N INTO ALLOW_STUFF FROM MY_TABLE WHERE MY_KEY = 'ALLOW_ME';
DBMS_OUTPUT.PUT_LINE(ALLOW_STUFF);
END;
I'm using SQL Developer and/or SQL PLus. When I run this, all I get is
Anonymous block completed
Rather than than the value of MY_TABLE.VAL_N
You need to enable output, otherwise the DBMS_OUTPUT.PUT_LINE statements are ignored.
Output can be enabled using:
DBMS_OUTPUT.ENABLE();
For more information about DBMS_OUTPUT read Oracle documentation: http://docs.oracle.com/cd/B19306_01/appdev.102/b14258/d_output.htm#i1000634
As stated in the comments also set serveroutput on can be used.
Related
I have an SQL statement in Oracle SQL developer that has some variables:
DEFINE custom_date = "'22-JUL-2016'" --run1
DEFINE custom_date = "'25-JUL-2016'" --run2
SELECT * FROM TABLE WHERE date=&custom_date
The real query is much more complicated and has many more variables and new tables are created from the results of the query. How can I create a script so that the query is executed twice, the first time with the custom date set as in the first line and the second time as in the second line.
In Oracle, the &variable is a "substitution variable" and is not part of SQL; it is part of the SQL*Plus scripting language (understood by SQL Developer, Toad etc.)
The better option, and what you are asking about, is BIND VARIABLES. The notation is :variable (with a colon : instead of &), for example :custom_date.
The difference is that a substitution variable is replaced by its value in the front-end application (SQL Developer in your case) before the query is ever sent to the Oracle engine proper. A bind variable is substituted at runtime. This has several benefits; discussing them is outside the scope of your question.
When you execute a query with bind variables in SQL Developer, the program will open a window where you enter the desired values for the bind variables. You will have to experiment with that a little bit till you can make it work (for example I never remember if a date must be entered with the single quotes or without). Good luck!
Define is used in TRANSACT SQL. To do this Oracle way, You can create anonymus PL/SQL block, similar to this:
DECLARE
p_param1 DATE;
p_param2 NUMBER;
CURSOR c_cur1(cp_param1 DATE,cp_param2 NUMBER)
IS
SELECT * FROM table WHERE date = cp_param1
;
BEGIN
-- Execute it first time
p_param1 := TO_DATE('2016-09-01','YYYY-MM-DD');
FOR r IN c_cur1(p_param1)
LOOP
NULL;
END LOOP;
-- Execute it second time
p_param1 := TO_DATE('2015-10-11','YYYY-MM-DD');
FOR r IN c_cur1(p_param1)
LOOP
NULL;
END LOOP;
END;
And in it, You create cursor with parameters and execute it twice with different parameter.
I do not know why You want to execute this query twice, so the script abowe does nothing with results, but it certainly should execute Your query twice, with different params.
I am able to get the result as CSV in Oracle by using this simple query with a hint.
SELECT /*csv*/ * FROM dual;
This returns
"DUMMY"
"X"
Now I would like to use exactly the same hint in PL/SQL in order not to reinvent the wheel.
SET SERVEROUTPUT ON;
declare
cur sys_refcursor;
csv_line varchar2(4000);
begin
open cur for select /*csv*/ * from dual;
loop
fetch cur into csv_line;
exit when cur%NOTFOUND;
dbms_output.put_line(csv_line);
end loop;
close cur;
end;
Unfortunately this prints only
X
which seems to ignore the hint.
Any way to do it that simple or do I have to write a special piece of code for exporting the data as CSV?
The /*csv*/ hint is specific to SQL Developer and it's sibling SQLCl; and is somewhat superseded by the set sqlformat csv option.
It is not a hint recognised by the optimiser; those are denoted by a plus sign, e.g. /*+ full(...) */ or less commonly --+ full(...).
If you're creating the output in PL/SQL you will need to construct the string yourself, adding the double quotes and delimiters. You can either have the cursor query do that so you can select into a single string even when you have multiple columns; or have a 'normal' query that selects into a record and have PL/SQL add the extra characters around each field as it's output.
It would be more normal to use utl_file than dbms_output as the client may not have that enabled anyway, but of course that writes to a directory on the server. If you're writing to a file on the client then PL/SQL may not be appropriate or necessary.
If you need to do some manipulation of the data in PL/SQL then one other option is to use a collection type and have an output/bind ref cursor, and then have SQL Developer print that as CSV. But you don't normally want to be too tied to a single client.
With Oracle dynamic SQL one is able to execute a string containing a SQL statement. e.g.
l_stmt := 'select count(*) from tab1';
execute immediate l_stmt;
Is it possible to not execute l_stmt but check that the syntax and semantics is correct programmitically?
EXPLAIN PLAN will check the syntax and semantics of almost all types of SQL statements. And unlike DBMS_SQL.PARSE it will not implicitly execute anything.
The point of the explain plan is to show how Oracle will execute a statement. As a side-effect of generating the plan it must also check syntax, privileges, and generally do everything except actually run the statement. The explain plan itself is pointless and can be ignored, the statement is only run to check for any errors. As long as there are no errors, the statement is valid.
For example, the PL/SQL blocks below check the validity of a SELECT statement and a CREATE TABLE statement. They run without error so the syntax is fine.
begin
execute immediate 'explain plan for select * from dual';
end;
/
begin
execute immediate 'explain plan for create table just_some_table(a number)';
end;
/
Running a bad statement will generate an error. In at least this one test case, it generates the same error as if the statement was run by itself.
begin
execute immediate 'explain plan for select * from this_table_does_not_exist';
end;
/
ORA-00942: table or view does not exist
ORA-06512: at line 2
The syntax diagram in the manual implies it should run for all statements. However, there appear to be at least a few statement types that do not work, such as ALTER SESSION.
begin
execute immediate 'explain plan for alter session set optimizer_features_enable = ''11.2.0.4''';
end;
/
ORA-00900: invalid SQL statement
ORA-06512: at line 2
Slightly off-topic - are you trying to build a completely generic SQL interface, like a private SQL Fiddle built in PL/SQL? Do you need to worry about things like preventing users from attempting to run certain statement types, and ensuring there are no trailing semicolons? If so I can edit the question to help with some of those difficult dynamic SQL tasks.
I think that the only "solution" is to use DBMS_SQL.PARSE().
It is not perfect but it is the best that you can get
Hope this way you can check the query formed before execution.
set serveroutput on;
DECLARE
lv_sql VARCHAR2(1000);
lv_cnt PLS_INTEGER;
BEGIN
lv_sql:='select count(*) from tab1';
dbms_output.put_line(lv_sql);
--EXECUTE IMMEDIATE lv_sql INTO lv_cnt;
END
I'm Facing below error:
An unexpected token "(" was found following " CURSOR ". Expected tokens may include: "CURSOR". SQLSTATE=42601
And I'm just trying to create a simple cursor, actually the example one found here in IBM documentation.
Cursor declaration looks something like:
DECLARE
CURSOR c1 (max_wage NUMBER) IS
SELECT * FROM emp WHERE sal < max_wage;
Not sure if this is do to the version of DB2 being used or not. Can anyone suggest maybe an alternative to creating a parameterized cursor?
You are trying to use PL/SQL syntax in DB2. This requires changes to the server environment. If you want to support the Oracle datatypes as well, the database must be created with the right settings, too. See this article for more details. The summary of that article is:
Open a DB2 Command Window (in Administrator mode)
Run db2start
Run db2set DB2_COMPATIBILITY_VECTOR=ORA
Run db2set DB2_DEFERRED_PREPARE_SEMANTICS=YES
Run db2stop
Run db2start
Execute your PL/SQL statements, e.g. in a DB2 CLP (run db2 -tv) command window.
Note that you should run
SET SQLCOMPAT PLSQL; in your DB2 CLP before trying PL/SQL. This enables using a forward slash (/) as a PL/SQL statement terminator. You should then obviously also then actually terminate your command with a forward slash :)
Here's an example taken from your link, modified to work with the default SAMPLE database in DB2:
SET SQLCOMPAT PLSQL;
DECLARE
my_record emp%ROWTYPE;
CURSOR c1 (max_wage integer) IS
SELECT * FROM employee WHERE salary < max_wage;
BEGIN
OPEN c1(40000);
LOOP
FETCH c1 INTO my_record;
EXIT WHEN c1%NOTFOUND;
DBMS_OUTPUT.PUT_LINE('Name = ' || my_record.firstnme || ', salary = '
|| my_record.salary);
END LOOP;
CLOSE c1;
END;
/
If you don't want to do all the above, then use the standard DB2 cursor syntax:
DECLARE [cursor name] CURSOR FOR [...]
...but that doesn't support parameterized cursors. To do so, I'd recommend creating a stored procedure taking the parameter. This stored procedure can then create a cursor using that parameter directly in the SQL.
I used to do Oracle development many many years ago. I have spent most of the past 15 years doing mainly SQL Server, and where I have done Oracle work, been insulated from the workings by Web services etc.
My question seems to have been asked on the web a few times, but it seems difficult somehow to communicate - at least judging by the answers. I very much appreciate that tools and functionality differ, know I have to learn new things, but this is so simple, yet seems so hard to do.
I am looking to do some ad-hoc queries on the database. At the moment we are using SQL Navigator - I am open to using other tools...
In SQL Server Management Studio, if you open a query window, type a bit of SQL that retuns a value or a set, you get a nice display of the rows or values in a results window.
I've gathered that with Oracle PL/SQL things are a bit different, worked out that I need to return a cursor - but how do I get a tool to display the results?
I started simple:
declare
my_id number := 356655;
cursor c1 is select my_id from dual;
begin
open c1;
end;
This runs fine - but how do I see the results? Are there any tools that deal with this as 'nicely' as SSMS? I am used to being able to do a lot of this, including stuff like
(perhaps not exactly the right syntax? but you get the idea...)
declare
my_id number := 356655;
cursor c1 is select name from my_table where id = my_id;
begin
open c1;
And having the results displayed to me as text/grid. Ideally that there is a nice solution. Some spiffy new tool, maybe?
With SQL Developer or SQL*Plus you can use a bind variable declared before the PL/SQL block:
variable rc refcursor;
declare
my_id number := 356655;
begin
open :rc for select my_id from dual;
end;
/
print rc
RC
-------------------------------
356655
You can also use a bind variable within the query, which can be useful:
variable my_id number;
variable rc refcursor;
execute :my_id := 356655;
begin
open :rc for select :my_id from dual;
end;
/
print rc
The variable and print commands are covered in the SQL*Plus documentation, which largely applies to SQL Developer as well - that has its own documentation, including the commands that are carried over from SQL*Plus.
If you have a function that returns a ref cursor then you can call that in a query, as select func(val) from dual, and then the results can go in a grid; or you can call the function (or procedure) with the same :rc bind variable and print it. But I'm not sure either is helpful if you are only doing ad hoc queries.
On the other hand, using a PL/SQL block for an ad hoc query seems a little heavy-handed, even if your queries are complicated. You'd need a good reason to open a cursor for a select statement from within a block, rather than just running the select directly. (Not sure if that's a SQL Server thing or if you actually have a real need to do this!). If you're just running a query inside the block, you don't need the block, even if you want to keep a bind variable for the values you're using in the query:
variable my_id number;
execute :my_id := 356655;
select :my_id from dual;
:MY_ID
----------
356655
I use Oracle SQL Developer.
Anyway, this should work in any oracle sql client:
If you just want to see your results, you can use
dbms_output.put_line('Foo' || somevar || ' bar');
Before this, run
SET SERVEROUTPUT ON
Check the examples at docs.oracle.com
I would suggest using sql developer available free from the oracle website. There is a button which allows you to run sql as a script which will get back what you want. SSMS doesn't work with pl/sql.