I would like convert the column name to date.
for example the column name is today, i want to convert it dynamically to today's date like MM/DD/YYYY .
as of now the column name is "Today" i want it to be current date
You can't configure a column to change its name automagically. To reflect the current day or whatever else.
But, you can change the column name by using an alias when doing a query. In order to make the things the more transparent as possible, you might want to create a view. Here is an example:
-- Some table with a column named "TODAY"
CREATE TABLE T AS (SELECT LEVEL today FROM DUAL CONNECT BY LEVEL < 5);
-- Use PL/SQL to create a view on the given table
-- with a dynamic column name
DECLARE
today varchar(10) := TO_CHAR(SYSDATE,'DD/MM/YYYY');
query varchar(200) := 'CREATE OR REPLACE VIEW V'
|| ' AS SELECT today "' || today || '"'
|| ' FROM T';
BEGIN
execute immediate query;
END;
Then, to query the "table" with the right column name, you will simply need to query V instead of T:
SELECT * FROM V;
12/12/2014
1
2
3
4
If you recreate your view daily, say by calling the above PL/SQL code from a job, you will see each day a view with the current date as the column name. But, as the underlying table is left unchanged, you will still be able to query it using the canonical name today. Which is important for example if you need to perform join on that table.
That being said, I'm not sure I will push toward such a solution. Use at your own risks!
If you want the column name heading to appear as something different than what the column name is defined in the table, you simply use the as "DisplayColumnName" clause for that column:
select user_name, today as "12/12/2014" from some_table;
But you would need to programatically generate the SQL statement for that to work. What coding environment you are using would dictate how to dynamically create a select statement.
Related
I am trying to replace all of the NULL values to 0 in a column of a big table in HIVE.
However, every time I try to implement some code I end up generating a new column to the table. The column I am trying to change/modify still exists and still has the NULL values but the new column that is automatically generated (i.e. _c1) is what I want the column I am trying to modify, to look like.
I tried to run a COALESCE but that also ended up generating a new column. I also tried to implement a CASE WHEN, but the same results ensued.
Select *,
CASE WHEN columnname IS NULL THEN 0
ELSE columnname
END
from tablename;
Also tried
SELECT coalesce(columnname, CAST(0 AS BIGINT)) FROM tablename
I would just like to update the table with the other columns being as is but the column I want to modify still has its original name but instead of NULL values it has 0's that replaced them.
I don't want to generate a new column but modify an existing one.
How should I do that?
Use insert overwrite .. option.
insert overwrite table tablename
select c1,c2,...,coalesce(columnname,0) as columnname
from tablename
Note that you have to specify all the other column names required in select.
I have data in the date column as below.
reportDate
21-Jan-17
02-FEB-17
I want to write a query to fetch data for 01/21/2017?
Below query not working in Oracle.
SELECT * FROM tablename where reportDate=to_date('01/21/2017','mm/dd/yyyy')
What is the data type of reportDate? It may be DATE or VARCHAR2 and there is no way to know by just looking at it.
Run describe table_name (where table_name is the name of the table that contains this column) and see what it says.
If it's a VARCHAR2 then you need to convert it to a date as well. Use the proper format model: 'dd-Mon-rr'.
If it's DATE, it is possible it has time-of-day component; you could apply trunc() to it, but it is better to avoid calling functions on your columns if you can avoid it, for speed. In this case (if it's really DATE data type) the where condition should be
where report_date >= to_date('01/21/2017','mm/dd/yyyy')
and report_date < to_date('01/21/2017','mm/dd/yyyy') + 1
Note that the date on the right-hand side can also be written, better, as
date '2017-01-21'
(this is the ANSI standard date literal, which requires the key word date and exactly the format shown, since it doesn't use a format model; use - as separator and the format yyyy-mm-dd.)
The query should be something like this
SELECT *
FROM table_name
WHERE TRUNC(column_name) = TO_DATE('21-JAN-17', 'DD-MON-RR');
The TRUNC function returns a date value specific to that column.
The o/p which I got when I executed in sqldeveloper
https://i.stack.imgur.com/blDCw.png
I have a table that has a StartDate and EndDate field, and also a ton of other fields. I need to break out each record by all the days between and including StartDate & EndDate into another table that looks exactly like the original except it has a CurrentDate field and 2 calculated fields. The CurrentDate field is the current date between StartDate and EndDate that I'm interating on.
My question is, since there are a ton of fields in this, is there any easy way from within my stored proc, to insert the entire row the cursor is currently on AND this 1 new column, without having to list out every single row in the insert statement? It's so tedious.
If your source and destination tables fit this profile:
Destination table columns are the same as your source table's columns, and
The new destination column is at the end
... then you could do something like this:
INSERT INTO dest_table
SELECT Source_Table.*, new_value
FROM Source_Table
WHERE Source_Table.PKValue = cursor.PKValue
If it's a case of your cursor resembling the destination table, something like this may work but note I haven't tested it:
CREATE PROCEDURE whatever IS
destRow dest_table%ROWTYPE;
CURSOR fromSourceTable IS
SELECT <your existing select list>, NULL AS new_value
FROM <the rest of your cursor query>;
BEGIN
FOR destRow IN fromSourceTable LOOP
destRow.new_value = <the split date>;
INSERT INTO dest_table VALUES destRow;
END LOOP;
END whatever;
I'm going out on a limb with the NULL AS new_value. If you have trouble try CAST(NULL AS DATE) AS new_value instead, and if you still have trouble try something like SYSDATE AS new_value. Again, this isn't tested but if you think it's promising and have trouble implementing I'd be happy to test it.
It's easy enough to densify the data in a single SQL statement. Assuming that you know a reasonable minimum and maximum range for your begin_date and end_date (I'll assume Jan 1, 2000 - Dec 31, 2020 for the moment but you can obviously adjust that)
WITH all_days AS (
SELECT date '2000-01-01' + level dt
FROM dual
CONNECT BY level <= date '2020-12-31' - date '2000-01-01'
)
SELECT <<list of colums from your table>>,
all_days.dt current_date
FROM your_table actual
JOIN all_days ON (actual.begin_date <= all_days.dt AND
actual.end_date >= all_days.dt)
If you don't want to hard-code the starting and ending dates, you can fetch them from your table as well. That just requires that you hit the table a second time which will generally be less efficient.
I want to have a column in table which calculates the value depending on the other column in the same table.
For example,
I have "Validity" Table with Columns "DateManufactured", "DateExpires"
The Date Expires column must calculate value suppose adding 30 days for Datemanufactured.
How Can we do this in Visual Studio2010->DataSet Design-> DataTable Column-> Properties->Expression
See relevant Image here
What could be the possible expression for this in terms of SQL Server Expressions?
Please Suggest optimal Solution.
Thanks in advance.
I believe you are looking for DateAdd
SELECT DATEADD(day, 30, '15 Dec 1988')
select dateadd(day,30,getdate())
this will take the current date(getdate())
add 30 days to it.
I would suggest creating a stored procedure to insert your data into your table with parameters of the values that needs to be inserted. you can then do your calculation based on your date parameter. Example:
Create Procedure InsertValidity
(
#City varchar(20),
#Area varchar(20),
...
#DatePosted datetime,
...
#UserID
)
as
declare #DurationFrom datetime
set #DurationFrom = (select DATEADD(dd,30,#DatePosted)
insert into Validity (City, Area, ..., DatePosted, ... UserID)
values(#City, #Area, ..., #DatePosted,...#DurationFrom,...#UserID)
This should solve your problem. Just complete the script by replacing the ... with your other data then execute the stored procedure in your application.
I need to search rows entered on a specific date.
However the datatype of column I need to search on is datetime, and the datatype of argument is Date.
I can use the the query like
Select result
from table
where
convert(date, Mycolumn) = #selectedDate
but this would affect the SARGability of the query and will not use indexes created on mycolumn.
I was trying to use the following query:
Select result
from table
where
Mycolumn
BETWEEN #selectedDate AND Dateadd(s, -1, Dateadd(D, 1, #selectedDate))
However this does not work since the #selectedDate is Date type and a second can't be added or removed.
Can someone help me with a working query?
Thanks.
It is my understanding that using:
convert(date, Mycolumn) = #selectedDate
is SARGable. It will use the index on Mycolumn (if one exists). This can easily be confirmed by using the execution plan.
Select result
from table
where
Mycolumn >= #selectedDate
AND Mycolumn < Dateadd(D, 1, #selectedDate)
If you need to do these searches a lot, you could add a computed, persisted column that does the conversion to DATE, put an index on it and then search on that column
ALTER TABLE dbo.YourTable
ADD DateOnly AS CAST(MyColumn AS DATE) PERSISTED
Since it's persisted, it's (re-)calculated only when the MyColumn value changes, e.g. it's not a "hidden" call to a stored function. Since it's persisted, it can also be indexed and used just like any other regular column:
CREATE NONCLUSTERED INDEX IX01_YourTable_DateOnly ON dbo.YourTable(DateOnly)
and then do:
SELECT result FROM dbo.YourTable WHERE DateOnly = #SelectedDate
Since that additional info is stored in the table, you'll be using a bit more storage - so you're doing the classic "space vs. speed" trade-off; you need a bit more space, but you get more speed out of it.