How can I put a table name dynamically in a query?
Suppose I have a query as shown below:
Select a.amount
,b.sal
,a.name
,b.address
from alloc a
,part b
where a.id=b.id;
In the above query I want to use a table dynamically (part b if the database is internal, p_part b if the database if external).
I have a function that returns which database it is. Suppose the function is getdatabase();
select decode(getdatabase(),'internal','part b','external','p_part b')
from dual;
How can I use this function in my main query to insert the table name dynamically into the query?
I don't want to implement this using the primitive way of by appending strings to make a final query and then open cursor with that string.
I don't want to implement this with primitive way of by appending
strings to make a final query and then open cursor with that string .
That's really the only way you can do it. It's not possible to use a variable or function call for the table name when using a regular PL/SQL SQL block, you have to use dynamic SQL.
Refer to Oracle documentation for more details:
http://docs.oracle.com/cd/B10500_01/appdev.920/a96590/adg09dyn.htm
Here's an example from the doc:
EXECUTE IMMEDIATE 'SELECT d.id, e.name
FROM dept_new d, TABLE(d.emps) e -- not allowed in static SQL
-- in PL/SQL
WHERE e.id = 1'
INTO deptid, ename;
You can do this without dynamic SQL, assuming both tables (part and p_part) are available at compile time:
select a.amount
,b.sal
,a.name
,b.address
from alloc a
,part b
where a.id=b.id
and (select getdatabase() from dual) = 'internal'
UNION ALL
select a.amount
,b.sal
,a.name
,b.address
from alloc a
,p_part b
where a.id=b.id
and (select getdatabase() from dual) = 'external'
;
I've put the function call in a subquery so that it is run only once per call (i.e. twice, in this instance).
Related
I am trying to recreate a query that uses a subquery in the left join to get the value of a KPI. I am trying to store that subquery in another table as a string and use dynamic sql to retrieve that string code and insert it into the left join, but I am getting an error:
[5526] SPL2010:E(L27), Variable of CHARACTER type expected in PREPARE or EXECUTE IMMEDIATE statement.
Here is the procedure I am trying to create. In the variable metric_code, the column SQL is a string that contains the sql code.
Create PROCEDURE dyn_sql_test()
BEGIN
DECLARE metric_code VARCHAR(5000);
Set metric_code = (Select SQL_CODE from mytable_with_Sql_code where ID=1234);
BEGIN
set get_value='
SELECT
e.*
,a.value
FROM Metric_table AS e
LEFT JOIN ('||metric_code||') a
on e.id=a.id
WHERE e.ID = 1234;';
EXECUTE IMMEDIATE get_value;
END;
END;
In case it helps, the string I am retrieving for SQL_CODE, which used to go in the Left Join as a subquery looks something like this:
sel id,type,values
from my_values_table
where type='kpi'
Hi friends am writing a stored procedure that selects and inserts data from one table to another table in the same database but different users, to speed up the insert am trying to use bulk collect and forall but the problem is am using dynamic SQL in the procedure that picks table name, it's corresponding primary key name and the date validation columns from another status table
For eg: consider the following query
Select empid from emp_tab where trunc(insert_time)=trunc(sysdate)
Here the PRIMARY KEY - empid, TABLENAME- emp_tab, date validation column - insert_time will be dynamically picked by the procedure during run time of the procedure from another status table but am not able incorporate the bulk collect and forall into dynamic SQL for bulk collect am getting
inconsistent data type
error and forall am getting
virtual column
error
Does bulk and forall supports dynamic sql????
If not then is there any other way to speed up the insert like forall
Any suggestions are welcome
Thanks in advance
Yes, they do. Despite BULK COLLECT being a powerful tool, it can be tricky with all its limitation. Here is a example using REF CURSOR, but you can build the TYPES according to your necessity.
-- create source data
CREATE TABLE temp_table_source AS
(SELECT ROWNUM id,
dbms_random.String('U', 10) name,
Round(dbms_random.Value(1, 7000)) salary
FROM dual
CONNECT BY LEVEL <= 5000 -- number of rows for the test
);
-- create destination table (empty)
CREATE TABLE temp_table_dest AS
SELECT * FROM temp_table_source WHERE 1 = 2;
-- Dynamic bulk anonymous block
DECLARE
v_stmt VARCHAR2(100);
v_insert VARCHAR2(100);
TYPE rec_source IS RECORD ( -- a type to represent your data
id temp_table_source.id%TYPE,
name temp_table_source.name%TYPE,
salary temp_table_source.salary%TYPE
);
TYPE t_source IS TABLE OF rec_source;
m_source t_source;
TYPE l_cursor_type IS REF CURSOR;
l_cursor l_cursor_type;
BEGIN
v_stmt := 'SELECT * FROM temp_table_source where 1 = :x';
v_insert := 'INSERT INTO temp_table_dest (id, name, salary) VALUES (:a, :b, :c)';
OPEN l_cursor FOR v_stmt USING 1; -- example of filtering
LOOP -- use limits to test performance, but the LOOP is optional
FETCH l_cursor BULK COLLECT INTO m_source LIMIT 1000;
--
FORALL i IN 1 .. m_source.COUNT
EXECUTE IMMEDIATE v_insert
USING m_source(i).id, m_source(i).name, m_source(i).salary;
--
COMMIT;
EXIT WHEN m_source.COUNT = 0;
END LOOP;
END;
/
-- See the result
Select count(1) from temp_table_dest;
If you need a dynamic TYPE as well, you will need to create it and drop at the end of your procedure instead of declare it in your package.
I have SQL query like this:
select * from dbo.table1 where Id in
(
select max(id) as id from dbo.table1 group by prop1, prop2, prop3
)
I want to create NHibernate query which is be able to do this for me. I tried to use QueryOver but it doesn't work. Do you have any suggestions how to do it?
NHibernate supports even this kind of queries. Please, see more in documentation: 15.8. Detached queries and subqueries. We just have to split the query (as in your SQL snippet) into two parts:
inner select
the select with the IN clause
Let's assume, that the dbo.table1 in the Questin is mapped into MyEntity.
To create inner select, let's use the DetachedCriteria
EDIT (extended with the Group by, SqlGroupProjection)
There is an extract of the SqlGroupProjection method:
A grouping SQL projection, specifying both select clause and group by
clause fragments
// inner select
DetachedCriteria innerSelect = DetachedCriteria
.For(typeof(MyEntity))
.SetProjection(
Projections.ProjectionList()
.Add(
Projections.SqlGroupProjection(
" MAX(ID) ", // SELECT ... max(ID) only
" Prop1, Prop2, Prop3", // GROUP BY ... property1, p2...
new string[] {"ID"}, // could be empty, while not used for
new IType[] { NHibernate.NHibernateUtil.Int32 } // transformation
)
)
;
Note: I've provided even the last two paramters, but in this case they could be empty: new string[], new IType[] {}. These are used only for Transformation (materialization from data into entity). And this is not the case, we are just building inner select...
// the select with IN clause
var result = session.CreateCriteria(typeof(MyEntity))
.Add(Subqueries.PropertyIn("ID", innerSelect))
.List<MyEntity>();
Also related could be 15.7. Projections, aggregation and grouping
I am having trouble getting a block of pl/sql code to work. In the top of my procedure I get some data from my oracle apex application on what checkboxes are checked. Because the report that contains the checkboxes is generated dynamically I have to loop through the
APEX_APPLICATION.G_F01
list and generate a comma separated string which looks like this
v_list VARCHAR2(255) := (1,3,5,9,10);
I want to then query on that list later and place the v_list on an IN clause like so
SELECT * FROM users
WHERE user_id IN (v_list);
This of course throws an error. My question is what can I convert the v_list to in order to be able to insert it into a IN clause in a query within a pl/sql procedure?
If users is small and user_id doesn't contain commas, you could use:
SELECT * FROM users WHERE ',' || v_list || ',' LIKE '%,'||user_id||',%'
This query is not optimal though because it can't use indexes on user_id.
I advise you to use a pipelined function that returns a table of NUMBER that you can query directly. For example:
CREATE TYPE tab_number IS TABLE OF NUMBER;
/
CREATE OR REPLACE FUNCTION string_to_table_num(p VARCHAR2)
RETURN tab_number
PIPELINED IS
BEGIN
FOR cc IN (SELECT rtrim(regexp_substr(str, '[^,]*,', 1, level), ',') res
FROM (SELECT p || ',' str FROM dual)
CONNECT BY level <= length(str)
- length(replace(str, ',', ''))) LOOP
PIPE ROW(cc.res);
END LOOP;
END;
/
You would then be able to build queries such as:
SELECT *
FROM users
WHERE user_id IN (SELECT *
FROM TABLE(string_to_table_num('1,2,3,4,5'));
You can use XMLTABLE as follows
SELECT * FROM users
WHERE user_id IN (SELECT to_number(column_value) FROM XMLTABLE(v_list));
I have tried to find a solution for that too but never succeeded. You can build the query as a string and then run EXECUTE IMMEDIATE, see http://docs.oracle.com/cd/B19306_01/appdev.102/b14261/dynamic.htm#i14500.
That said, it just occurred to me that the argument of an IN clause can be a sub-select:
SELECT * FROM users
WHERE user_id IN (SELECT something FROM somewhere)
so, is it possible to expose the checkbox values as a stored function? Then you might be able to do something like
SELECT * FROM users
WHERE user_id IN (SELECT my_package.checkbox_func FROM dual)
Personally, i like this approach:
with t as (select 'a,b,c,d,e' str from dual)
--
select val
from t, xmltable('/root/e/text()'
passing xmltype('<root><e>' || replace(t.str,',','</e><e>')|| '</e></root>')
columns val varchar2(10) path '/'
)
Which can be found among other examples in Thread: Split Comma Delimited String Oracle
If you feel like swamping in even more options, visit the OTN plsql forums.
Is it possible to use SELECT FROM when using an associative array? I'm passing an array to a stored procedure through a .NET application, and I wanna be able to use that array as a condition when selecting from another table. Lets say I'm passing an array of IDs to the procedure, I wanna be able to do this:
select * from table1 where userID in (select column_value from array)
The type for the array is defined in the package:
type id_array is type of number index by pls_integer
Yes, it is possible, by wrapping the array with a pipelined function. Here's a good primer on pipelined functions:
http://www.oracle-developer.net/display.php?id=429
UPDATE: Oracle 12c now supports querying associative arrays using the TABLE operator, as long as the type is declared in a package spec: https://galobalda.wordpress.com/2014/08/02/new-in-oracle-12c-querying-an-associative-array-in-plsql-programs/
e.g.
select * from table1
where userID in (select column_value from table(array));
No, you can't select from PL/SQL arrays, since you use SQL in select from statements, though you can use DB defined Nested Tables types in SQL. This short article can help you get started.
Take a look a this simple synthetic exmple:
> create type temp_t as table of int;/
Type created.
> select 'test' from dual where 1 in (select * from table(temp_t(1,2,3)));
'TES
----
test
An example using PLSQL (to select from a nested table):
create type temp_r as OBJECT(
temp_varchar2 varchar2(100),
temp_number number(20)
);
/
create type temp_t as TABLE of temp_r;
/
set serveroutput on size 1000000
/
-- PLSQL starts here
declare
temp_rec temp_r := temp_r(null, null); -- empty constructor to initialize object
temp_table temp_t := temp_t(); -- empty constructor to initialize object
lv_ref_cursor SYS_REFCURSOR;
lv_temp_varchar2 varchar(100);
lv_temp_number number(20);
begin
temp_rec.temp_varchar2 := 'first';
temp_rec.temp_number := 1;
temp_table.extend;
temp_table(1) := temp_rec;
temp_table.extend;
temp_table(2) := temp_r('second', 2);
OPEN lv_ref_cursor FOR
SELECT temp_varchar2, temp_number
FROM table(temp_table)
where temp_number = 1;
fetch lv_ref_cursor into lv_temp_varchar2, lv_temp_number;
close lv_ref_cursor;
dbms_output.put_line('returns: ' || lv_temp_varchar2 || ', ' || lv_temp_number);
end;
/