SQL & PL/SQL :: View Not Having ORDER BY Clause In SELECT Statement?
Jun 13, 2010
currently i m going through some dumps for my OCA-11g prep.I came across one sentence :A view cannot have an ORDER BY clause in the SELECT statement.well this statement is false and the explanation given was :
Query operations containing ORDER BY clause are also permitted, so long as the ORDER BY clause appears outside the parentheses.
The following is an example of what I mean: CREATE VIEW my_view AS (SELECT*FROM emp) ORDER BYempno.
but when i tried running the query like this :CREATE VIEW my_view AS SELECT*FROM emp ORDER BYempno ,it worked w/o giving parentheses.
In the following merge statement in the USINg clause...I am using a select stament of one schema WEDB.But that same select statement should take data from 30 schemeas and then check the condition below condition
ON(source.DNO = target.DNO AND source.BNO=target.BNO);
I thought that using UNIONALL for select statement of the schemas as below.
I'm using pivot query feature of oracle 11g and came across a strange situation where i need to pass a "select statement" in a "in clause" of pivot query.
I have tried with pivot xml but it not giving desired output in sql*plus session.It is giving unreadable output.
select * from (select uin,testing_id,pfa_result from test1) pivot xml (max(pfa_result) as result for (testing_id) in (select distinct testing_id from test1));
[code]....
Here actually i want to use "select distinct id from test1" instead of "in (11,12,13,14,15)". Because i don't know how many id's will be there and of which values. e.g. 11 or 21 or 25.
Need a trigger in view with select statement that means
CREATE OR REPLACE VIEW TEST_VIEW AS SELECT * FROM TEST_TABLE; CREATE OR REPLACE TRIGGER TEST_VIEW_TRG1 INSTEAD OF DELETE ON TEST_VIEW DECLARE BEGIN Dbms_Output.Put_Line('STATEMENT TRIGGER.'); END;
i wanted to use select statement instead of delete.How can i get that
I have requirement to create an XML structure through stored procedure. I need to Order some of the columns in ascending order before I format them into the xml structure. I am pretty novice to creating an output into XML format, but attached is the query I came up with (without order by). This works perfect, but now the requirement is to order by - cls_cd, and within cls_cd, again order by - cat_cd. I am not able to do this.
I have a requirement where I need to display a list of employees, performance rating and manager id. I want to display the employees first whose manager is as manager_id as input parameter. So lets say a manager logs in, he should see his reporters first and then the rest. How can I implement this in SQL? I am trying first clause with order by but not sure how to do that here.
I have got the following error while executing below Query.
ORA-01791 'Not a SELECTed expression'
select distinct sgbstdn_levl_code from sgbstdn,spriden where spriden_pidm = sgbstdn_pidm and spriden_id = '200076543' order by sgbstdn_term_code_eff desc;
The above Query is not working with Distinct & Order By clause are present and by joining two tables. I need the distinct values of levels in Descending order of Terms.
When i try to execute a query, which is organised as the below example, it retrieves data..
select * from ( select col1, col2, col3, col4....coln from TABLE_ONE left outer join TABLE_TWO -- some conditions and group by clause order by 1 asc ) where rownum <=1000;
Again if I use Column alias in the ORDER BY clause col1, the query won't retrieve data.
Also If I use ORDER BY 4 instead of ORDER BY 1, the query wont return data...
select * from ( select col1, col2, col3, col4....coln from TABLE_ONE left outer join TABLE_TWO -- some conditions and group by clause order by 4 asc ) where rownum <=1000;
The whole issue revolves around the inner ORDER BY Clause and external ROWNUM condition..If I eliminate any of the two, the query works fine...I am not sure if indexes have some role to play in it...
select col1, col2, col3, col4 from tab1, tab2, tab3 where conditions union
[Code]...
Now, the col4 is a date column and I have to order by the entire result sets on it. I know I can do it by (order by col4) or by (order by 4) at the end of the entire query.
But the problem is that, the output is coming in dd-Mon-yyyy (i.e 31-Nov-2012).
I want every output in dd/mm/yyyy format so I need to use to_char function.
But in that case, I cant use the order by clause, because in that case it is getting arranged by character i.e by 1,2,3,4,5 like this.
I have a real problem with form, specifically one of its data blocks. In the order by property of the block i specify it to sort on a branch in ascending order(i tried descending as well) but for some reason the form ignores that and sorts it on the ROWNUM. I even removed the where clause, the order by clause and changed the query data source type to FROM clause and changed the data source name to pre-query. I then created the query string in the block's pre-query trigger and set query_data_source_name property to that query string and still the data in the block is not being sorted on the branch number but instead on the ROWNUM.
How to avoid sort operation by an order by clause without changing the sort area size.what hints or changes should be done in query so that order by clause work faster.
I came across situation where a Nullable column is not using index for 'order by' clause. I added Not Null condition in the 'where' condition but it wasn't useful. I don't wanted to make composite index with not nullable column or with constant or modify column to 'Not Null'
So I carried out test cases and during which I found that in one case the sql statement does 'fast full scan' for data access but does not use index for 'order by' sorting
here are the steps
Initially I kept the column Nullable
SQL> create sequence s5; Sequence created.
SQL> create table t5 as select s5.nextval id,a.* from dba_objects a where rownum<1001; Table created.
SQL> set pages 100 SQL> select column_name,nullable from user_tab_columns where table_name='T5';
Misses in library cache during parse: 1 Optimizer mode: ALL_ROWS Parsing user id: 5
Rows Row Source Operation ------- --------------------------------------------------- 1000 SORT ORDER BY (cr=16 pr=0 pw=0 time=4771 us) 1000 TABLE ACCESS FULL T5 (cr=16 pr=0 pw=0 time=1157 us)
Elapsed times include waiting on following events: Event waited on Times Max. Wait Total Waited ---------------------------------------- Waited ---------- ------------ SQL*Net message to client 68 0.00 0.00 SQL*Net message from client 68 49.49 49.72 ********************************************************************************
select /*+ index(t i5) */ * from t5 t where id is not null order by id
Misses in library cache during parse: 1 Optimizer mode: ALL_ROWS Parsing user id: 5
Rows Row Source Operation ------- --------------------------------------------------- 1000 TABLE ACCESS BY INDEX ROWID T5 (cr=150 pr=0 pw=0 time=5167 us) 1000 INDEX FULL SCAN I5 (cr=71 pr=0 pw=0 time=3141 us)(object id 4673065)
Elapsed times include waiting on following events: Event waited on Times Max. Wait Total Waited ---------------------------------------- Waited ---------- ------------ SQL*Net message to client 69 0.00 0.00 SQL*Net message from client 69 22.89 28.04
Now I modified the 'id' column to Not Null
SQL> alter table t5 modify id not null;
SQL> set pages 100 SQL> select column_name,nullable from user_tab_columns where table_name='T5';
COLUMN_NAME N ------------------------------ - ID N OWNER Y OBJECT_NAME Y SUBOBJECT_NAME Y OBJECT_ID Y DATA_OBJECT_ID Y OBJECT_TYPE Y CREATED Y LAST_DDL_TIME Y TIMESTAMP Y STATUS Y TEMPORARY Y GENERATED Y SECONDARY Y
Misses in library cache during parse: 1 Optimizer mode: ALL_ROWS Parsing user id: 5
Rows Row Source Operation ------- --------------------------------------------------- 1000 SORT ORDER BY (cr=16 pr=0 pw=0 time=2398 us) 1000 TABLE ACCESS FULL T5 (cr=16 pr=0 pw=0 time=1152 us)
Elapsed times include waiting on following events: Event waited on Times Max. Wait Total Waited ---------------------------------------- Waited ---------- ------------ SQL*Net message to client 68 0.00 0.00 SQL*Net message from client 68 37.74 37.91 ********************************************************************************
Misses in library cache during parse: 1 Optimizer mode: ALL_ROWS Parsing user id: 5
Rows Row Source Operation ------- --------------------------------------------------- 1000 TABLE ACCESS BY INDEX ROWID T5 (cr=150 pr=0 pw=0 time=4166 us) 1000 INDEX FULL SCAN I5 (cr=71 pr=0 pw=0 time=3142 us)(object id 4673065)
Elapsed times include waiting on following events: Event waited on Times Max. Wait Total Waited ---------------------------------------- Waited ---------- ------------ SQL*Net message to client 68 0.00 0.00 SQL*Net message from client 68 8.28 8.45
Misses in library cache during parse: 1 Optimizer mode: ALL_ROWS Parsing user id: 5
Rows Row Source Operation ------- --------------------------------------------------- 1000 SORT ORDER BY (cr=6 pr=0 pw=0 time=1342 us) 1000 INDEX FAST FULL SCAN I5 (cr=6 pr=0 pw=0 time=1093 us)(object id 4673065)
Elapsed times include waiting on following events: Event waited on Times Max. Wait Total Waited ---------------------------------------- Waited ---------- ------------ SQL*Net message to client 68 0.00 0.00 SQL*Net message from client 68 1.88 1.89
Questions are
1) Why adding 'where id is not null wasn't enough for the index to get used in 'order by'? 2) While we got 'fast full scan' why index wasn't used for 'order by' clause? 3) Do we need the indexed column in where clause for being used in 'order by clause' too? 4) Do we need 'order by' clause if we are selecting only the indexed column with sequence generated values?
We wrote one data load process to load GZ files into Database.during process we will change client facing view definitions to backup table so that we can work on base tables.
This view definition changes are related to FROM and WHERE clause (not columns/type). during load process, client/user may connect to current server and accessing these views. My question is what will be the reflection of changing view definition while user is accessing view?
I created a scenario- STEP1: Created a view- create or replace view view_01 as select object_name from dba_objects union all select object_name from dba_objects union all select object_name from dba_objects union all [code]....
View definition is replaced by new definition while select is executing on that view. select returned number of records as per view definition one.
I am using JDBC to run a few queries from my Java program (multi-threaded one).I am facing an issue where a select statement is blocking a delete statement. From the java code point of view, there are 2 different threads accessing the same tables (whith different DB connection objects).
When the block occurs (which i was able to find out from the java thread dump that there is a lock on oracle), the below is the output:
SQL> SELECT TO_CHAR(sysdate, 'DD-MON-YYYY HH24:MI:SS') 2 || ' User '||s1.username || '@' || s1.machine 3 || ' ( SID= ' || s1.sid || ' ) with the statement: ' || sqlt2.sql_text ||' is blocking the SQL statement on '|| s2.username || '@' 4 5 || s2.machine || ' ( SID=' || s2.sid || ' ) blocked SQL -> ' 6 ||sqlt1.sql_text AS blocking_status FROM v$lock l1, v$session s1, v$lock l2 , 7 v$session s2,v$sql sqlt1, v$sql sqlt2 8 WHERE s1.sid =l1.sid 9 AND s2.sid =l2.sid AND sqlt1.sql_id= s2.sql_id AND sqlt2.sql_id= s1.prev_sql_id AND l1.BLOCK =1 10 AND l2.request > 0 AND l1.id1 = l2.id1 AND l2.id2 = l2.id2; [code]...
From the above it can be seen that a select statement is blocking a delete. Unless the select is select for Update, it should not block other statements is not it ?
Select clause or Order by clause? First the columns specified in the select clause are fetched and then ordered or is it the vice -versa? In a query if a psuedo-column rownum is selected, then if we use order by on the rownum column, what happens?
What would be the output of the following query and why?Which part of the query is first executed, is it select clause or order by clause?
select empno,ename,rownum from emp order by rownum desc;
select empno,ename,deptno,employee_status from emp,dept where emp.deptno=dept.deptno and ( employee_status in(Case employee_status when {?Status}=1 then 'A' when {?Status}= 2 then 'T' When {?Status}= 3 then 'A'||','||'T')) OR ( end_date >= {?START_DATE} AND end_date <= {?END_DATE} ) )
Since when i pass employee_status as input 1 it have given me 4 records. When I pass employee_status as input 2 it have given me 3 records. When I pass employee_status as input 3 it should give me 4 records + 3 records=7 records.
4 records for employee_status 'A' 3 RECORDS for employee_status 'T' 7 records for employee_status 'A' AND 'T'
