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
Related
I want to convert a column in the format mm/dd/yyyy to datetime, but when I do I get the following error:
The conversion of a varchar data type to a datetime data type resulted in an out-of-range value.
I found in other posts that this means that some dates don't make sense, such as 10/35/2021. I tried to find the wrong dates by slicing the varchars to get the dates with SUBSTRING(date, 3, 2) but it turns out some dates are in the form m/d/yyyy, so when I slice I get something like 1/.
I have no idea how to find the wrong dates, and how to (even though there are wrong dates) convert everything to datetime.
Thanks!
If some of your data is in MM/dd/YYYY and some M/d/yyyy this really makes for a bit of a mess. I would likely do something like this:
--Add a new varchar column (yes varchar) to save a copy of your bad data
ALTER TABLE dbo.YourData ADD BadDate varchar(10);
GO
--Change the data you have to the ISO format yyyyMMdd and store the bad data in the BadDate column
UPDATE dbo.YourData
SET DateColumn = CONVERT(varchar(8),TRY_CONVERT(date,DateColumn,101),112),
BadDate = CASE WHEN TRY_CONVERT(date,DateColumn,101) IS NULL THEN DateColumn END
WHERE DateColumn IS NOT NULL;
GO
--Change data type of your data column
ALTER TABLE dbo.YourData ALTER COLUMN DateColumn date NULL;
GO
--You can view your bad data with:
SELECT BadData
FROM dbo.YourData
WHERE BadData IS NOT NULL;
If you just want to locate rows with values that are obviously bad dates - disregarding any ambiguities - just use try_convert and check for NULLs
eg
with dates as (
select * from (values('01/02/2021'),('02/01/2021'),('33/02/2021'),('01/13/2021'))v(d)
)
select *
from dates
where Try_Convert(date, d) is null
I have an issue where I created a column sent_Date of type nvarchar while it's storing date and time.
Now when I try to sort it by date, it's not doing so correctly.
I am using this query:
select *
from tbl_skip
where sent_date > '9/27/2020 7:29:11 PM'
order by SENT_DATE desc
Like the comments have said, the real solution here is fix your design. That means changing the column's data type an nvarchar to a date and time data type, I'm going to use a datetime2(0) here, as your data is accurate to a second, so seems the most appropriate.
Firstly we need to convert the value to as ISO value. I'm also, however, going to create a new column called Bad_Sent_Date, to store values that could not be converted. Experience has taught many of us that systems that incorrectly use string data types to store dates (or numerical data) rarely have good data integrity rules on the value (because if they did, it wouldn't be an nvarchar) to start, so have bad values like '29/02/2019' or mix styles, such as having both '09/29/2020' and '29/09/2020'.
Based on the single example we have, I will assume your data is supposed to be in the format MM/dd/yy hh:mm:ss AM/PM:
ALTER TABLE dbo.tbl_skip ADD Bad_Sent_Date nvarchar(30) NULL;
GO
UPDATE TABLE dbo.tbl_skip
SET Bad_Sent_Date = CASE WHEN TRY_CONVERT(datetime2(0),Sent_date,101) IS NULL THEN Sent_date END,
Sent_Date = CONVERT(nvarchar(30),TRY_CONVERT(datetime2(0),Sent_date,101),126);
GO
Now we have an ISO format, we can change the table's data type:
ALTER TABLE dbo.tbl_skip ALTER COLUMN Sent_date datetime2(0) NULL;
Note that if you do have constraints on the column Sent_date, or it isn't NULLable, you will first need to DROP said CONSTRAINTs, change the column to be NULLable and then recreate said CONSTRAINTs after you have altered the column.
You can also review the "dates" that failed to be converted with the following:
SELECT bad_sent_date
FROM dbo.tbl_skip
WHERE bad_sent_date IS NOT NULL
AND Sent_date IS NULL;
Once that's all done, then your query simply needs an update to use an unambiguous date literal, and it'll work:
SELECT *
FROM tbl_skip
WHERE sent_date > '2020-09-27T19:29:11' --'9/27/2020 7:29:11 PM'
ORDER BY SENT_DATE DESC;
You can convert the data from string to datetime.
Please note i used 100 as an example to convert to date time. You can use below link to see if its behaving correctly. link -https://www.w3schools.com/sql/func_sqlserver_convert.asp
select *
from tbl_skip
where sent_date > convert(datetime,'9/27/2020 7:29:11 PM',100)
ORDER BY CONVERT(datetime,SENT_DATE,100) desc
You should be able to convert it to a datetime
select *
from tbl_skip
where sent_date > '9/27/2020 7:29:11 PM'
order by convert(datetime,SENT_DATE) desc
Just make sure the data in column is legit. If so, it would make sense to convert the column type to a datetime.
alter table tbl_skip alter column SENT_DATE datetime
If the data is mixed, you may need to fix it or use something like
order by try_convert(datetime,SENT_DATE) desc
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
I've found some similar questions but haven't been able to get anything to work yet. I'm very much a novice with little SQL experience.
I have a column END_DATE as Varchar(10) where all the rows follow the mm/dd/yyyy format and I would like to convert it to date. I have an empty column formatted as date if that helps. There are 36 million rows.
SELECT CONVERT(DATETIME,YourColumn,101) FROM YourTable
101 is mm/dd/yyyy format.
You zany backwards americans :)
To update your existing column
UPDATE YourTable
SET YourNewColumn = CONVERT(DATETIME,YourOldColumn,101)
Since it appears you have invalid data, use this method to isolate it:
UPDATE YourTable
SET YourNewColumn = CONVERT(DATETIME,YourOldColumn,101)
WHERE SomeTableKey BETWEEN ASmallCode AND ABiggerCode
Find a key in your table that you can use to divide up the data and try updating half the table... now halve it again and again until you find the offending data. Post the data here and we will come up with some code to allow for it.
I think you should convert END_DATE to DATETIME type, because you have 36 million rows and it will give a performance boost when you do not have to cast or convert it datetime with select statement.
To answer your question, you can do something like
select CAST(END_DATE AS DATETIME) FROM MyTable
The PARSE (SQL 2012) or CONVERT (any version) can do the conversion for you. Your UPDATE query will look something like one of these statements:
UPDATE the_table SET the_column = PARSE(end_date AS datetime2 USING 'en-US')
UPDATE the_table SET the_column = CONVERT(datetime2, end_date, 101)
DECLARE #End_DATE VARCHAR(10);
SET #End_DATE = '12/20/2013';
SELECT CAST(#End_DATE AS DATE)
RESULT: 2013-12-20
Empty Column formatted as Date, I am guessing you meant to say you have DATE datatype column and you would like to update this VARCHAR(10) date to , Date datatype column you could do something like this....
UPDATE Table_Name
SET New_End_DATE = CAST(End_DATE AS DATE)
Working SQL FIDDLE
I have a table with two date column. However the columns are in varchar. I need to covert them as date format.
The sample data is like this:
Account Number | Registration Date | System Status Change Date
01740567715 | 10-JUL-13 | 30-JUL-13 12.53.32.000000000 PM
I want both of these columns like this: 10-Jul-2013.
For Registration Date, I am using this code:
Update [dbo].[SysDataV2]
Set ["REGISTRATION_DATE"]= convert(datetime, (["REGISTRATION_DATE"]), 106)
But it is shwoing the result as varchar and also showing erroneous format.
For System Status Change Date I am using following code:
update [dbo].[SysData]
Set ["KYC_STATUS_CHANGED_DATE"]= REPLACE(CONVERT(datetime,convert(datetime,left(["KYC_STATUS_CHANGED_DATE"],9),103),106),' ' ,'-')
Both are changing to date format of some type (not my expected format) but in table structure they are still shown as varchar.
What am I doing wrong here?
The table's data type is still varchar. An update merely changes the string, it doesn't change the data type. What you should do is (assuming all of the dates are valid and this format is 100% consistent):
UPDATE dbo.SysData SET REGISTRATION_DATE =
CONVERT(CHAR(10), CONVERT(DATE, REGISTRATION_DATE, 106), 120);
UPDATE dbo.SysData SET KYC_STATUS_CHANGED_DATE =
CONVERT(CHAR(10), CONVERT(DATETIME, LEFT(KYC_STATUS_CHANGED_DATE, 9), 106), 120)
+ REPLACE(SUBSTRING(KYC_STATUS_CHANGED_DATE, 10, 9), '.',':')
+ RIGHT(KYC_STATUS_CHANGED_DATE, 2);
ALTER TABLE dbo.SysData ALTER COLUMN REGISTRATION_DATE DATE;
ALTER TABLE dbo.SysData ALTER COLUMN KYC_STATUS_CHANGED_DATE DATETIME;
And then stop inserting regional and potentially problematic strings. String literals representing dates / datetimes should be:
-- date only
YYYYMMDD
-- with time:
YYYY-MM-DDThh:mm:ss.nnn
But best is to simply make sure they are date or datetime values before you ever hand them off to SQL Server. Your application should be able to do this without ever converting to some arbitrary string format. Never, ever, ever store date or datetime values as strings in SQL Server. You gain nothing and you lose quite a lot.
You need to change the data type of the column from a varchar to store it as a Date. Then when you select it you can format it any way that you like. One way to do this would be to create a new column of the correct datatype and convert the data, then remove the old column. Make sure the the old column doesn't have and foreign key relationships or you will also need to transfer those over as well.
ALTER TABLE [dbo].[SysData] ADD ConvertedDate DateTime
UPDATE [dbo].[SysData] SET ConvertedDate = CAST(VarCharDate as DateTime)
ALTER TABLE [dbo].[SysData] DROP COLUMN VarCharDate