SQL & PL/SQL :: Function In Oracle To Select Not-null Columns At Beginning And Null Columns At End?
Jul 12, 2012
I have 8 columns. Some of them might be null.I want to display all 8 columns in my result. Not null columns will be first and null at the end.Here is a sample data :
I have a table containing hundreds of columns and I would like to be able to qualify my select statements so that only those columns containing a value are returned. Something like:
Select (non null columns) from tablename where columnX = 'whatever'
We are working on a migration project and we need to move 75 million rows from source system to target system.
Total number of columns in source system - 90 cols.
Out of the 90 columns 10 cols are system fields and rest 80 are properties for each record.
We are required to migrate all system cols and some required properties. In total we will migrate around 25 columns[10+15] for each record.
Before actaul migration , we need to do a data cleansing activity and hence we move the data to a staging table.
To create the staging table, we considered the below appraoches.
1. Create the staging table with around 30 coloumns so as to fit the data from source system[map the columns based on datatype]
2.Create the staging table with actual columns[90 columns] and import only the required properties. The rest all columns will remain NULL.
Do the data cleansing and move to target system.
My question here is, if we go with approach 2, We will not mix the data, as there will be a one-to-one mapping. But many columns will not have data and remain NULL. Will it affect the performance since we deal with 75 million rows.
I am experiencing somewhat same issue...but have been unable to resolve it(new to Oracle) I am getting the infile from flat file(data dump from SQL) using sqlldr to upload data to the Oracle table...since the data is already in the flat file...I cannot do anything in the SQL to pre-format the data...
Sample of ERROR I am getting - Column CREATE_DATE which has date and time - happens to other date time columns also if remove the CREATE_DATE from Control file(happens to every single line of record): ========================================== Record 2: Rejected - Error on table LGCY_CHS.METS_CHS_USER_PRIV, column CREATE_DATE. ORA-01841: (full) year must be between -4713 and +9999, and not be 0
I regularly upload various tab-delimited text data files with SQL Loader. The control files always specify TERMINATED BY X'09'. Certain columns in those data files may be null for some rows, i.e. there is no character between two subsequent tabs. It always works like a clock.
Now, I have run into a specific case where I have to strip a data column of double quotes that may or may not enclose the actual data (side effect of a text export from Excel).
I tried simply adding OPTIONALLY ENCLOSED BY '"' behind the terminated delimiter and it did work for the file and column in question. Still, with this new option, files with null values are no longer decoded correctly. The loader seems to simply skip those values, which provokes column shifts and results in either a corrupt load, or a load failure.
For now, I've got a workaround dropping the new option and executing an SQL script eliminating double quotes directly in the database, but that obviously cannot last.
im trying to select columns from different tables dynamically in a function . The parameter for the function will be table name and column id's, In this number of columns may vary . Is it possible to have dynamic %rowtype to store the cursor value in it.
I am running a GROUP BY query on a few columns of enumerated data like:
select count(*), Condition, Size group by Condition, Size;
COUNT(*) CONDITION SIZE -------- ---------- -------- 3 MINT L 2 FAIR L 4 FAIR M 1 MINT S
Well, let's say I also have a timestamp field in the database. I cannot run a group by with that involved because the time is recorded to the milisec and is unique for every record. Instead, I want to include this in my group by function based on whether or not it is NULL.
For example:
COUNT(*) CONDITION SIZE SOLDDATE -------- ---------- -------- ---------- 3 MINT L ISNULL 2 FAIR L NOTNULL 2 FAIR M NOTNULL 2 FAIR M ISNULL 1 MINT S ISNULL
i have a function which takes in two variables and return a varchar.
ex: Function(var1,var2) return as varchar2.
in the function,i query a table for var1 and var2 and concatenate the result set to return a varchar. But if either var1 or var2 is null,then my query in the function fetches the result set for the other variable.
My question is,how would i pass a null value through the function and handle it in the function.
My query returns the 3rd field from a CSV string. If the third field in the string is empty I want the select to return a null but it returns the 4th field :
SELECT REGEXP_SUBSTR( 'A,B,,D,E','[^,]+',1,3) from dual;
.. this returns 'D'.
Can we somehow make the REGEX_SUBSTR return a NULL for the third field ?
There is a table with column holding 3 NULL values one each in every record. When a count function is applied to the column with a filter on NULLs,it returns 0 instead of 3.
But when count(*)is applied,expected result is returned. Would be interested in knowing about this strange behavior of NULL/Count.
I want to implement a business rule such as we have for each id at most 1 dat null. So, I've created this unique index on test.
create unique index x_only_one_dat_cess_null on test(id, case when dat_cess is null then 'NULL' else to_char(dat_cess, 'dd/mm/yyyy') end);
insert into test values (1, sysdate); insert into test values (1, sysdate - 1); insert into test values (1, null); insert into test values (1, null); -- ----- insert into test values (2, sysdate); insert into test values (2, sysdate - 1); insert into test values (2, null);
The 4th insert will cause an error and this is what I wanted to implement. OK. Now the problem is that for non-null values of dat, we can't have data like this
because of the unique index (the 2nd and the 3rd row are equal). So just for learning purposes, how could we allow at most one null value of dat and allow duplicates for non-null values of dat.
SQL> Describe Stu_Table Name Null? Type ----------------------------------------- -------- ---------------------------- STU_ID VARCHAR2(2) STU_NAME VARCHAR2(10) STU_CLASS VARCHAR2(10)
now when i try to modify this Stu_id column to not null its give me error.
SQL>ALTER TABLE Stu_Table MODIFY Stu_Id int(3)not null; ALTER TABLE Stu_Table MODIFY Stu_Id int(3)not null * ERROR at line 1: ORA-01735: invalid ALTER TABLE option
and when i try to add new column with not null its also gives me error
SQL> ALTER TABLE Stu_Table add C1_TEMP integer NOT NULL; ALTER TABLE Stu_Table add C1_TEMP integer NOT NULL * ERROR at line 1: ORA-01758: table must be empty to add mandatory (NOT NULL) column
I got a requirement to check if a particular range of values are present , if few values missing then have to add null for the values. This has to be a SQL statement.
This is the table. the fiscal month id denotes that the values is from month Oct(20101000) to May (20110500). The fiscal year cycle for me is from OCT to SEP. Hence when we select this table, the select should retreive the below data
I want to create a report by using one field and one text as columns name in layout but display the all the columns. I mention the 5 column names in query.how can I write function in summary column.
I am running a fairly busy Oracle 10gR2 DB, one of the tables has about 120 columns and this table receives on average 1500 insertions per second. The table is partitioned and the partitioning is based on the most important of the two timestamp columns. There are two timestamps, they hold different times.
Out of these 120 columns, about 15 need to be indexed. Out of the 15 two of them are timestamp, at least one of these two timestamp columns is always in the where clause the queries.
Now the challenge is, the queries we run can have any combination of the 13 other columns + one timestamp. In reality the queries never have more than 7 or 8 columns in the where clause but even if we had only 4 columns in the where clause we would still have the same problem.
So if I create one concatenated index for all these columns it will not be very efficient because after the 4th or 5th column the sorting would no longer be very useful and I believe the optimiser would simply not use the rest of the index. So queries that use the leading columns of the index in sequence work well, but if I need to query the 10th column the I have performance issues.
Now, if I create multiple single column indexes oracle will have to work a lot harder to maintain all these indexes and it will create performance issues (I have tried that). Besides, if I have multiple single column indexes the optimiser will do nested loops twice or three times and will hit only the first few columns of the where clause so I think it will kind of be the same as the long concatenated index.
What I am trying to do is exactly what the Bitmap index would do, it would be very good if I could use the AND condition that a Bitmap index uses. This way I could have N number of single column indexes which the optimiser could pick from and serve the query with exactly the ones it needs. But unfortunately using the Bitmap index here is not an option given the large amount of inserts that I get on this table.
I have been looking for alternatives, I have considered creating multiple shorter concatenated indexes but this still would not address the issue since many queries would still not be served properly and therefore would take a very long time to complete.
What I had in mind would be some sort of multidimensional index, I am not even sure if such thing exists. But essentially it would be some sort of index that could serve a query efficiently regardless of the fact that the where clause has the 1st, 3rd and last columns of the index.
So considering how widely used Oracle is and how many super large databases there are out there, this problem must be common.
BANNER Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bi PL/SQL Release 10.2.0.5.0 - Production "CORE10.2.0.5.0Production" TNS for Linux: Version 10.2.0.5.0 - Production NLSRTL Version 10.2.0.5.0 - Production
See attached file for creation script and data load.Each staff member is required to complete at least one task every three years. The source table contains an EID (aka User ID) and a date column for each task with a date of when the task was completed. If a task has never been started/completed the date value is "NULL".
The result set will show the EID, date of latest task completed and if the task was completed within the last 3 years from given date (for example June 30, 2012).
Quote: select a.contact, b.db_name from MOM.db_contacts@DB_LINK a, MOM.databases@DB_LINK b, where a.DB_ID=b.DB_ID and b.DB_name=(SELECT unique substr(upper(t.target_name), 1, instr(t.target_name,'_',1,1)-1) FROM mgmt_targets t JOIN mgmt_current_severity s ON s.target_guid = t.target_guid WHERE t.target_type = 'oracle_database' and UPPER(t.target_name) like '%11GDB%');
How can I add two more columns into the select statement and the two columns are in the tables that were in the sub query..I would like to have something like this:
Quote: select a.contact, b.db_name, COLUM1, COLUMN2 from MOM.db_contacts@DB_LINK a, MOM.databases@DB_LINK b, mgmt_targets t, mgmt_current_severity s where a.DB_ID=b.DB_ID and b.DB_name=(SELECT unique substr(upper(t.target_name), 1, instr(t.target_name,'_',1,1)-1) FROM mgmt_targets t JOIN mgmt_current_severity s ON s.target_guid = t.target_guid WHERE t.target_type = 'oracle_database' and UPPER(t.target_name) like '%11GDB%');
I've read so many different pages on this topic but I can't seem to get my query the way it needs to be. Here's the query:
select admitnbr, lastname||', '||firstname||' '||finitial, hphone, mobile, wphone, med_rec, dob from patients join schedule using (key_patien) join adtmirro using (key_patien) where appt_state = 'ON HOLD'
Because patients in my database can have multiple appointments "on hold" there are duplicates in the results. I only need 1 record per patient in order to forward this information into an automated dialer to contact that patient. I do NOT want to call the patient over and over again. Once will suffice. I'm trying to make a distinction on the column 'med_rec'. One row per 'med_rec' will be awesome but I can't find a way to create a distinct on that column.
