My table table1 has the column date_txt which includes 2/16/2011 12:00:00 AM - column date_txt is VARCHAR2 (250 Char).
My table table1 also has the column date which is a DATE.
I would like to "update" my field:
The final output should be:
table1:
date
2/16/2011
So it takes from table1 date_txt the "date" and updates it to the column date as a date.
Any ideas? I am a bloody beginner.
You can use Oracle's to_date function to convert a string to a date:
update table1 set "date" = to_date(date_txt, 'MM/DD/YYYY HH:MI:ss AM')
See it working at SQL Fiddle.
column date_txt which includes 2/16/2011 12:00:00 AM
Firstly, DATE doesn't have any format. What you see is for display purpose to interpret date value easily.
Secondly, you should never ever store DATE as VARCHAR2. This is a big problem and a poor design.
Now that you have a bad design, it is a good idea to fix it right now.
Follow these steps:
Add a new column with DATE data type.
Update the new column with date values from the old column using TO_DATE.
Drop the old column.
Rename the new column to the old column.
I have already answered how to do it here https://stackoverflow.com/a/29625772/3989608
Try following:
update table1 set date=
(select to_date(date_txt,'dd/mm/yyyy') from table1 where id=yourId) where id=yourId;
Use primary key columns for ids.
If this is what you need everytime. I would suggest you to use Triggers
Related
I'm working on a table with a column, 'Expiry Date', as a varchar with all data formatted as DD/MM/YYYY.
The creator of the table has used the wrong type for this expiry date column and now the client needs to filter and show all records before and after the current date as the time. This means the type needs to be changed to date or datetime type to be able to use the CURDATE() function.
However, the current format of the values does not satisfy and wont allow the type to change unless the format is changed to YYYY-MM-DD (or similar).
Is there any way to mass format the values in this column and this column alone as there are thousands of entries and formatting one by one would be extremely time consuming.
Let me assume that you are using MySQL.
Perhaps the simplest method is to add a generated column that is a date:
alter table t add column expiry_date_date as
(str_to_date(expiry_date, '%d/%m/%Y'));
You can also fix the data:
update t
set expiry_date = str_to_date(expiry_date, '%d/%m/%Y');
This will implicitly convert the result of str_to_date() to a date, which will be in the YYYY-MM-DD format.
More importantly, you can then do:
alter table t modify column expiry_date date;
Here is a db<>fiddle.
You can do similar operations in other databases, but the exact code is a bit different.
What you need is an update on that column, but before doing it I suggest you to check if the result is what you want.
select replace(expiry_date, '/', '-') new_expiry_date
from table_name
If this returns the results you want you can run the following update:
update table_name
set expiry_date = replace(expiry_date, '/', '-')
Of course you will need to replace expiry_date and table_name with the names of your column and table.
A long time ago I created a database, and completely forgot to set the column to Date and now looking at the data, I want to extract, it looks like 2006-05-06.
How would I run a SQL statement to convert it into the correct format (dd/MM/yyyy) 06/05/2006, I'm running with the British format "103".
What I was planning on doing, I've already added a second column (s_batch_convert2) to the database, hoping to convert into that and then delete the original column (s_batch_convert), renaming the new column to the old one.
UPDATE s_service_repairs
SET s_batch_convert2 = TRY_CONVERT(Date, s_batch_convert, 103)
Am I along the right lines?
You should convert your existing column to a bona fide date. It seems to have the right format:
alter table s_service_repairs alter column s_batch_convert date;
Then you can add a computed column for the format you want:
alter table s_service_repairs s_batch_convert_mmddyyyy as ( try_convert(varchar(10), s_batch_convert, 103) );
I'm inserting data into a table and before inserting I need to check if data exists.
I have a composite key consisted of two columns of datetime and int.
Before inserting I need to check if the data with the same time and id exists in the table.
The date that user is inserting is in 'mm/dd/yyyy'.
The datetime data in the table looks like this: '2016-01-12 00:00:00.000'.
The id field is int.
So, I have a query:
if not exists(select count(*) from table_1 where MyDate = #myDate and id = #id)
insert into table_1 .....
What is the right way to format the date user sends to match the datetime format in the table?
Check this sqlfiddle about how to use different date formats in your query. Might help you to solve it.
http://www.sqlfiddle.com/#!2/fd0b7/5
I am guessing that the question is about SQL Server, based on the syntax. The issues in the code snippet far transcend date formats.
First, the expression:
if not exists(select count(*) from table_1 where MyDate = #myDate and id = #id)
will never return true, because the subquery always returns one row with one column. If nothing matches, the column contains 0, which does exist.
You intend:
if not exists(select 1 from table_1 where MyDate = #myDate and id = #id)
Second, this check is not necessary if you wisely choose to have the database enforce the uniqueness constraint. So, define a unique index or constraint on the two columns:
create unique index unq_table_1_id_mydate on table_1(id, MyDate);
Now, the database won't let you insert duplicate values and no if is necessary.
Next, I would suggest that you fix the date format at the application layer. YYYY-MM-DD is an ISO standard date format and quite reasonable. However, if you don't want to do that, use convert():
insert into table_1(id, MyDate, .....)
select #id, convert(datetime, #MyDate, 101), . . .
The value in the database looks to be correct stored as a date/time value, so this should work fine.
You can use following line to convert date to required format in SQL server:
select FORMAT(#your_date, 'yyyy-MM-dd HH:mm:ss', 'en-US') from Your_Table
I have a column in Oracle DB which is varchar2 data type. Typical value stored in this column is like 06/16/2015 02:14:18 AM.
I am trying to get all records wherein this column is having records after 1st August 2015.
select *
from MYTABLE
where to_date(substr(MYCOLUMN,1,10),'dd-mm-yyyy') > to_date('01-08-2015','dd-mm-yyyy');
But, I am getting ORA-01843. Where am I doing wrong?
Respect the format in your VARCHAR
....where to_date(substr(MYCOLUMN,1,10),'mm/dd/yyyy')
I have a column in Oracle DB which is varchar2 data type. Typical value stored in this column is like 06/16/2015 02:14:18 AM.
The first question is why do you store DATE as string? Using appropriate data type is one of the most important part of database design and performance.
Understand that DATE doesn't have the format you see, it is internally stored in 7 bytes which is Oracle's proprietary format. Storing date as a string to have a fixed format is not recommended.
I would suggest first fix the design so that you don't have to do this overhead activity while comparing dates. In the longer run it will help you.
1. Add a new column as DATE data type.
ALTER TABLE table_name
ADD new_column DATE;
2. Update the new column.
UPDATE table_name
SET new_column = TO_DATE(old_column, 'mm/dd/yyyy hh:mi:ss pm');
3. DROP the old column.
ALTER TABLE table_name
DROP COLUMN old_column;
4. Rename the new column to old column name.
ALTER TABLE table_name
RENAME COLUMN old_name to new_name;
Now, you could compare dates easily:
SELECT * FROM MYTABLE WHERE mycolumn > to_date('01-08-2015','dd-mm-yyyy');
This will also use any regular index on the date column.
From performance point of view:
If you don't fix it now, you will keep facing performance issues. Because the immediate fix of SUBSTR will not let you use any regular index, you need to create a function-based index.
If in your table all values like 06/16/2015 02:14:18 AM then you can use trunc(to_date(MYCOLUMN,'mm/dd/yyyy HH:mi:SS PM'),'dd') against to_date(substr(MYCOLUMN,1,10),'dd-mm-yyyy').
Question1:
Do i have to use to_date while inserting date?
INSERT INTO some_table (date1, date2)
VALUES (to_date('2012-10-24','YYYY-MM-DD'), to_date('2012-10-24','YYYY-MM-DD'));
Or can just insert as string? Will everything be OK this way too? I've tried and it worked.
INSERT INTO some_table (date1, date2)
VALUES ('2012-10-24',2012-10-24');
Question2:
What happens if i won't name columns that i'm inserting into? It works, but my question is if it inserts randomly now or it takes order of columns during creation of table?
INSERT INTO some_table
VALUES ('2012-10-24',2012-10-24');
1 seems to only work with the 'YYYY-MM-DD' format:
http://docs.oracle.com/cd/B28359_01/server.111/b28286/sql_elements003.htm#SQLRF51049 says
You can specify a DATE value as a string literal ... to specify a DATE value as a literal, you must use the Gregorian calendar. You can specify an ANSI literal... The ANSI date literal contains no time portion, and must be specified in the format 'YYYY-MM-DD'.
However, it might work with time if you use the
Alternatively you can specify an Oracle date value... The default date format for an Oracle DATE value is specified by the initialization parameter NLS_DATE_FORMAT.
For question 2, it uses the order at definition of the table. However you have to give values for all columns in that case.
Oracle supports Standard SQL date literals (since 9i).
It's DATE followed by a string with 'yyyy-mm-dd' format
DATE '2014-05-10'
It's much shorter than TO_DATE and it's independent of any NLS settings.
Similar for timestamps:
TIMESTAMP '2014-05-10 09:52:35'
Regarding your 2nd question: It's the order of columns as defined within the CREATE TABLE.
You could even do it like this one:
ALTER SESSION SET NLS_DATE_FORMAT = 'MM:YYYY:DD';
INSERT INTO some_table (date1) VALUES ('05:2014:10');
...but doing it like this is not recommended. Use TO_DATE or DATE Literal, e.g. DATE '2014-05-10' instead. It makes your life easier.