I'm attempting to write a simple query where I declare some variables and then use them in a select statement in Oracle. I've been able to do this before in SQL Server with the following:
DECLARE #date1 DATETIME
SET #date1 = '03-AUG-2010'
SELECT U.VisualID
FROM Usage u WITH(NOLOCK)
WHERE U.UseTime > #Date1
From the searching I've done it appears you can not declare and set variables like this in Select statements. Is this right or am I mssing something?
From the searching I've done it appears you can not declare and set variables like this in Select statements. Is this right or am I missing something?
Within Oracle PL/SQL and SQL are two separate languages with two separate engines. You can embed SQL DML within PL/SQL, and that will get you variables. Such as the following anonymous PL/SQL block. Note the / at the end is not part of PL/SQL, but tells SQL*Plus to send the preceding block.
declare
v_Date1 date := to_date('03-AUG-2010', 'DD-Mon-YYYY');
v_Count number;
begin
select count(*) into v_Count
from Usage
where UseTime > v_Date1;
dbms_output.put_line(v_Count);
end;
/
The problem is that a block that is equivalent to your T-SQL code will not work:
SQL> declare
2 v_Date1 date := to_date('03-AUG-2010', 'DD-Mon-YYYY');
3 begin
4 select VisualId
5 from Usage
6 where UseTime > v_Date1;
7 end;
8 /
select VisualId
*
ERROR at line 4:
ORA-06550: line 4, column 5:
PLS-00428: an INTO clause is expected in this SELECT statement
To pass the results of a query out of an PL/SQL, either an anonymous block, stored procedure or stored function, a cursor must be declared, opened and then returned to the calling program. (Beyond the scope of answering this question. EDIT: see Get resultset from oracle stored procedure)
The client tool that connects to the database may have it's own bind variables. In SQL*Plus:
SQL> -- SQL*Plus does not all date type in this context
SQL> -- So using varchar2 to hold text
SQL> variable v_Date1 varchar2(20)
SQL>
SQL> -- use PL/SQL to set the value of the bind variable
SQL> exec :v_Date1 := '02-Aug-2010';
PL/SQL procedure successfully completed.
SQL> -- Converting to a date, since the variable is not yet a date.
SQL> -- Note the use of colon, this tells SQL*Plus that v_Date1
SQL> -- is a bind variable.
SQL> select VisualId
2 from Usage
3 where UseTime > to_char(:v_Date1, 'DD-Mon-YYYY');
no rows selected
Note the above is in SQLPlus, may not (probably won't) work in Toad PL/SQL developer, etc. The lines starting with variable and exec are SQLPlus commands. They are not SQL or PL/SQL commands. No rows selected because the table is empty.
I have tried this and it worked:
define PROPp_START_DT = TO_DATE('01-SEP-1999')
select * from proposal where prop_start_dt = &PROPp_START_DT
The SET command is TSQL specific - here's the PLSQL equivalent to what you posted:
v_date1 DATE := TO_DATE('03-AUG-2010', 'DD-MON-YYYY');
SELECT u.visualid
FROM USAGE u
WHERE u.usetime > v_date1;
There's also no need for prefixing variables with "#"; I tend to prefix variables with "v_" to distinguish between variables & columns/etc.
See this thread about the Oracle equivalent of NOLOCK...
Try the to_date function.
Coming from SQL Server as well, and this really bugged me. For those using Toad Data Point or Toad for Oracle, it's extremely simple. Just putting a colon in front of your variable name will prompt Toad to open a dialog where you enter the value on execute.
SELECT * FROM some_table WHERE some_column = :var_name;
Related
I'm using PL/SQL Developer. I'm trying to get query results to excel via vba. Since query is so long, i decided to create table with the query results and then simply get the table results with vba. In order to create table via excel i needed to create procedure with dynamic sql. So this is what i tried so far (even this simple example doesn't work):
create or replace procedure d_x IS
str VARCHAR(81) = 'create table as select 1 as x from dual'
BEGIN
EXECUTE IMMEDIATE str;
END;
Procedure completes without error. But when i try to execute it to create table it throws an error.
Execute statement:
EXECUTE d_x;
The execute statement throws 'ORA-00900' Invalid sql statement error.
I'm kinda new to pl sql so i couldn't find a solution to this.
Any help would be appreciated, thanks.
Procedure you posted can't possibly execute without errors because it is invalid. When fixed, looks like this:
SQL> create or replace procedure d_x IS
2 str VARCHAR(81) := 'create table test as select 1 as x from dual';
3 BEGIN
4 EXECUTE IMMEDIATE str;
5 END;
6 /
Procedure created.
In tools that support execute, you can run it as:
SQL> execute d_x
PL/SQL procedure successfully completed.
SQL> select * from test;
X
----------
1
"Correct" way - which works anywhere - is to enclose it (the procedure) into begin-end block:
SQL> drop table test;
Table dropped.
SQL> begin
2 d_x;
3 end;
4 /
PL/SQL procedure successfully completed.
SQL>
I suggest you do that.
In PL/SQL Developer you can click on the procedure name and choose 'Test', which will generate a calling script as a Test window.
You can only use execute in a Command window, because it's a SQL*Plus command and not part of SQL or PL/SQL, and the Command window is a SQL*Plus emulator.
In a SQL window you could either use a complete PL/SQL block:
begin
d_x;
end
/
or use the SQL call command:
call d_x();
Note that call() requires brackets regardless of whether or not the procedure has any parameters.
The / character is useful as a separator when using PLSQL blocks in a SQL window where you have more than one statement, otherwise PL/SQ Developer won't know where one ends and the next starts.
A Test window can only have one statement and only a single PL/SQL block or SQL statement is allowed, so there is no / character at the end.
I'm writing a SQL procedure which should use calculated date stored as a local variable in a select statement. I'm using Oracle SQL developer. My code is:
create or replace PROCEDURE
my_procedure
AS
BEGIN
DECLARE
l_max_dt DATE;
BEGIN
SELECT MAX(TRX_DT)
INTO l_max_dt
FROM TABLE
WHERE 1=1;
end;
select * from TABLE where trx_dt = l_max_dt;
end;
This code gives me an error : " Error(14,48): PL/SQL: ORA-00904: "L_MAX_DT": invalid identifier" when select statement is present.
How can I store variables to use them in statements?
This is how you write a Procedure. Syntax is incorrect. Read about syntax Here
CREATE OR REPLACE PROCEDURE my_procedure
AS
l_max_dt DATE;
v_var TABLE2%ROWTYPE;
BEGIN
SELECT MAX (TRX_DT)
INTO l_max_dt
FROM TABLE1
WHERE 1 = 1;
-- Assuming the query will retrun only 1 row.
SELECT *
INTO v_var
FROM TABLE2
WHERE trx_dt = l_max_dt;
END;
Your issue is one of scope. In your procedure, you have a nested block, in which you declare the l_max_dt variable. Once the code has exited that block, the l_max_dt variable is no longer in scope - i.e. the outer block does not know anything about it.
There is no need to have a nested block in this instance - you can do it all in the same block, like so:
create or replace PROCEDURE my_procedure
AS
l_max_dt DATE;
BEGIN
SELECT MAX(TRX_DT)
INTO l_max_dt
FROM TABLE
WHERE 1=1;
-- commented out as this isn't valid syntax; there is a missing INTO clause
-- select *
-- from TABLE where trx_dt = l_max_dt;
END my_procedure;
However, you could simply do the query in one fell swoop - e.g.:
select *
from your_table
where trx_dt = (select max(trx_dt) from your_table);
A couple of points about your procedure:
In PL/SQL, if you use an implicit cursor (i.e. when you put a select statement directly in the body of the code) you need to have something to put the results into. You could bulk collect the results into an array, or you could ensure that you will receive exactly one row (or code error handling for NO_DATA_FOUND and TOO_MANY_ROWS) into a record or corresponding scalar variables.
You shouldn't use select * in your procedure - instead, you should explicitly state the columns being returned, because someone adding a column to that table could cause your procedure to error. There are exceptions to this "rule", but explicitly stating the columns is a good habit to get into.
I was writing a PL/SQL procedure to come up with a report.
Here is part of my scripts where I tested and had the compilation error.
I believe it's not the syntax of the select into clause, but I don't know the exact problem when assigning value to the date variables...
Did anyone encounter this error before?
DECLARE
v_bc_mth DATE;
BEGIN
SELECT TRUNC(ADD_MONTHS(SYSDATE, -1)) INTO v_bc_mth FROM dual; --what's wrong with the clause
SELECT * FROM bc WHERE v_bc_mth BETWEEN bc_start_date AND bc_end_date;
END;
PLS-00428: an INTO clause is expected in this SELECT statement
06550. 00000 - "line %s, column %s:\n%s"
*Cause: Usually a PL/SQL compilation error.
You need the INTO clause for both SELECT statements.
However, do you really need to use PL/SQL?
You could do it all in SQL, avoiding context switches with:
SELECT *
FROM bc
WHERE TRUNC(ADD_MONTHS(SYSDATE, -1)) BETWEEN bc_start_date AND bc_end_date;
Or, you could rewrite what you have so there is only one switch to SQL from within your PL/SQL block as:
DECLARE
TYPE bc_tabtype IS TABLE OF bc%ROWTYPE
INDEX BY pls_integer;
--
bc_tab bc_tabtype;
BEGIN
SELECT *
BULK COLLECT INTO bc_tab
FROM bc
WHERE TRUNC(ADD_MONTHS(SYSDATE, -1)) BETWEEN bc_start_date AND bc_end_date;
-- Do what you want with the results you now have in the Associative Array bc_tab
END;
You might need to look up associative arrays and BULK COLLECT etc. to understand them.
Tom Kyte, the Oracle VP states it succinctly when he says:
I have a pretty simple mantra when it comes to developing database
software, and I have written this many times over the years:
You should do it in a single SQL statement if at all possible.
If you cannot do it in a single SQL statement, do it in PL/SQL.
If you cannot do it in PL/SQL, try a Java stored procedure.
If you cannot do it in Java, do it in a C external procedure.
If you cannot do it in a C external procedure, you might want to seriously think about why it is you need to do it.
EDIT:
In light of your comment, try this:
DECLARE
v_bc_mth DATE := TRUNC(ADD_MONTHS(SYSDATE, -1));
--
TYPE bc_tabtype IS TABLE OF bc%ROWTYPE
INDEX BY pls_integer;
--
bc_tab bc_tabtype;
BEGIN
SELECT *
BULK COLLECT INTO bc_tab
FROM bc
WHERE v_bc_mth BETWEEN bc_start_date AND bc_end_date;
END;
I use a cursor for the statement:
SELECT NAME FROM STUDENT WHERE ROLL = 1;
I used:
CURSOR C IS SELECT NAME FROM STUDENT WHERE ROLL = roll;
--roll is a variable I receive via a procedure, and the procedure works fine for the received parameter.
Upon executing this, I am able to retrieve all records with roll = 1.
Now, I need to retrieve the records of a group (possibly via a cursor), just like:
SELECT NAME FROM STUDENT WHERE ROLL IN (2, 4, 6);
But the values in the IN clause are known only at run time. How should I do this? That is, is there any way I could assign parameters to the WHERE clause of the cursor?
I tried using an array in the declaration of the cursor, but an error pops up telling something like: standard types cannot be used.
I used:
CURSOR C IS SELECT NAME FROM STUDENT WHERE ROLL IN (rolls);
--rolls is an array initialized with the required roll numbers.
First, I assume that the parameter to your procedure doesn't actually match the name of a column in the STUDENT table. If you actually coded the statement you posted, roll would be resolved as the name of the column, not the parameter or local variable so this statement would return every row in the STUDENT table where the ROLL column was NOT NULL.
CURSOR C
IS SELECT NAME
FROM STUDENT
WHERE ROLL = roll;
Second, while it is possible to use dynamic SQL as #Gaurav Soni suggests, doing so generates a bunch of non-sharable SQL statements. That's going to flood the shared pool, probably aging other statements out of cache, and use a lot of CPU hard-parsing the statement every time. Oracle is built on the premise that you are going to parse a SQL statement once, generally using bind variables, and then execute the statement many times with different values for the bind variables. Oracle can go through the process of parsing the query, generating the query plan, placing the query in the shared pool, etc. only once and then reuse all that when you execute the query again. If you generate a bunch of SQL statements that will never be used again because you're using dynamic SQL without bind variables, Oracle is going to end up spending a lot of time caching SQL statements that will never be executed again, pushing useful cached statements that will be used again out of the shared pool meaning that you're going to have to re-parse those queries the next time they're encountered.
Additionally, you've opened yourself up to SQL injection attacks. An attacker can exploit the procedure to read any data from any table or execute any function that the owner of the stored procedure has access to. That is going to be a major security hole even if your application isn't particularly security conscious.
You would be better off using a collection. That prevents SQL injection attacks and it generates a single sharable SQL statement so you don't have to do constant hard parses.
SQL> create type empno_tbl is table of number;
2 /
Type created.
SQL> create or replace procedure get_emps( p_empno_arr in empno_tbl )
2 is
3 begin
4 for e in (select *
5 from emp
6 where empno in (select column_value
7 from table( p_empno_arr )))
8 loop
9 dbms_output.put_line( e.ename );
10 end loop;
11 end;
12 /
Procedure created.
SQL> set serveroutput on;
SQL> begin
2 get_emps( empno_tbl( 7369,7499,7934 ));
3 end;
4 /
SMITH
ALLEN
MILLER
PL/SQL procedure successfully completed.
create or replace procedure dynamic_cur(p_empno VARCHAR2) IS
cur sys_refcursor;
v_ename emp.ename%type;
begin
open cur for 'select ename from emp where empno in (' || p_empno || ')';
loop
fetch cur into v_ename;
exit when cur%notfound;
dbms_output.put_line(v_ename);
end loop;
close cur;
end dynamic_cur;
Procedure created
Run the procedure dynamic_cur
declare
v_empno varchar2(200) := '7499,7521,7566';
begin
dynamic_cur(v_empno);
end;
Output
ALLEN
WARD
JONES
Note:As mentioned by XQbert,dynamic cursor leads to SQL injection ,but if you're not working on any critical requirement ,where security is not involved then you can use this .
Maybe you can pass rolls as a set of quoted comma separated values.
e.g. '1', '2' etc
If this value is passes into the procedure in a varchar input variable, the it can be used to get multiple rows as per the table match.
Hence the cursor
SELECT NAME FROM STUDENT WHERE ROLL IN (rolls);
will be evaluated as
SELECT NAME FROM STUDENT WHERE ROLL IN ('1','2');
Hope it helps
I have a fairly complex query that will be referencing a single date as a start or stop date multiple times throughout. I'm going to have to run this query for 3 different fiscal years, and don't want to have to hunt down the date 17 times in order to change it throughout my query.
Is there a way to set a variable at the beginning of my query and reference it throughout? I'm not looking to write a whole function, just reference a variable throughout my query.
Yes, depends how you want to do it.
You could use an anonymous procedure IE:
BEGIN
v_date DATE := TO_DATE(your_date, your_date_mask);
[your query referencing v_date where ever you need];
END;
Or if you run the query in SQLPlus, you use & to note variables (IE: &your_date), and will be prompted for the value when you run the script.
As OMG Ponies says, inside PL/SQL you can always refer to any PL/SQL variable (including parameters) right in the SQL as long as it's static SQL. Outside PL/SQL, or if your SQL is dynamic (because native dynamic SQL doesn't support reusable named parameters at least as of 10g) you can use the following trick. Add the following before the WHERE clause in your query:
CROSS JOIN (SELECT :dateparam Mydate FROM dual) Dateview
And everywhere you want to refer to that value in your main query, call it Dateview.Mydate Then when you execute the query, you need only pass in the one bind parameter.
You're not really saying how you reference this so I'll just show from SQL*Plus point of view.
Two ways
Have it prompt you for the value. Since you use the same variable many times you'll want to use the && operator.
SQL> SELECT &&var, &&var FROM Dual;
Enter value for var: 'PUMPKIN'
old 1: SELECT &&var, &&var FROM Dual
new 1: SELECT 'PUMPKIN', 'PUMPKIN' FROM Dual
'PUMPKI 'PUMPKI
------- -------
PUMPKIN PUMPKIN
Alternatively you could set it before you ran your SQL.
SQL> VARIABLE new_var VARCHAR2(20);
SQL> EXECUTE :new_var := 'PUMPKIN PIE';
PL/SQL procedure successfully completed.
SQL> SELECT :new_var, :new_var FROM DUAL;
:NEW_VAR :NEW_VAR
-------------------------------- --------------------------------
PUMPKIN PIE PUMPKIN PIE
If you use Toad with second mouse button -> Execute as Script, so not prompt you for values:
var myVar varchar2(20);
exec :req := 'x';
delete from MYTable where Field =
:myVar;