I have a bunch of values in the form of mm/dd/yyyy stored in a CSV. An example is 06/26/2017. What I found was that I could NOT insert it into a column declared as date or datetime2 type. What I CAN do is to modify that (empty) column to varchar first, then insert.
However at this point, after insertion as varchars, how can I convert this column to "date" or "datatime2"?
Attempting to set system-wide format doesn't work:
sql> SET DATEFORMAT 'mm/dd/yyyy'
[2019-03-31 09:42:04] [S0001][2741] SET DATEFORMAT date order 'mm/dd/yyyy' is invalid.
If the column's data type is date then convert the string to date with:
convert(date, '03/31/2019', 101)
and then insert it.
See the demo.
Read more about convert()
Edit:
Create a varchar column and a date column. Insert the values inside the varchar column and when the process finishes, update the date column by converting each value to a date, like:
UPDATE tablename
SET datecolumn = convert(date, varcharcolumn, 101)
After that you can remove the varchar column.
Related
FORMAT instruction works in a SELECT but has no effect in an UPDATE:
SELECT ##VERSION
DROP TABLE IF EXISTS #t;
CREATE TABLE #t(DateMin datetime);
INSERT INTO #t VALUES ('2019-13-01 00:00:00')
SELECT * FROM #t
UPDATE #t SET DateMin = FORMAT(DateMin, 'dd/MM/yyyy');
SELECT * FROM #t;
SELECT #DateMin AS a, FORMAT(#DateMin, 'dd/MM/yyyy') AS b
A type like DATETIME isn't stored with a format.
So if one updates a DATETIME with a string in a certain format, it doesn't matter for the stored value in the DATETIME field.
The formatted string is implicitly converted to a datetime. At least if it's in a format that's valid.
The function FORMAT, which returns a NVARCHAR is rather used for representation of the datetime field in a query.
Or if one wants to INSERT/UPDATE a string field with a datetime in a certain format. But that should be avoided, because it's much easier to work with a datetime than a string.
If you want to change that format for the user use this:
set dateformat dmy;
By running this statement:
DBCC USEROPTIONS;
you will see your dateformat is ydm so you can alway back it up to that if this is not what you wanted :)
You cannot set the output format of a datetime in the datetime itselfs.
If you need to output the datetime as formatted char/varchar, you need to use the convert-function when you select the data:
SELECT CONVERT(char(10), CURRENT_TIMESTAMP, 101) -- format: MM/dd/yyyy
SELECT CONVERT(char(10), CURRENT_TIMESTAMP, 103) -- format: dd/MM/yyyy
In your case:
SELECT #DateMin AS a, CONVERT(char(10), #DateMin, 103) AS b
That works as expected.
If you want to have a mutable data-type, you need to declare it as sql_variant:
DROP TABLE IF EXISTS #t;
CREATE TABLE #t(DateMin sql_variant);
INSERT INTO #t VALUES ('2019-01-13T00:00:00')
UPDATE #t SET DateMin = FORMAT(CAST(DateMin AS datetime), 'dd''/''MM''/''yyyy');
SELECT * FROM #t;
Also, your format-expression needs to explicitly put the / into quotation marks, aka 'dd''/''MM''/''yyyy', otherwise sql-server replaces it with the date-separator specific to the current culture, which would be . in my case.
Just use convert with option 103 instead, it works on all versions of sql-server and it's probably faster.
Also, your insert-statement fails on some versions of sql-server, because iso-date-format is 2019-01-13T00:00:00 and not 2019-13-01 00:00:00
Correct is:
INSERT INTO #t VALUES ('2019-01-13T00:00:00')
Also
DROP TABLE IF EXISTS #t;
is sql-server 2016+ only, otherwise you need
IF OBJECT_ID('tempdb..#t') IS NOT NULL DROP TABLE #t
And post sql-server 2005, you should use datetime2 instead of datetime.
You shouldn't use datetime anymore, because datetime uses float, and as such is imprecise - if you insert an iso datetime value, it can do funny things because of the float-point-machine-epsilon, e.g. set it to the next day if you have 23:59:59.999, just as a scary example.
I advise you to never use the sql_variant type. If you have a temp-table with defined columns, just create another column where you will write the char/varchar value to.
The date format in the table is YYYYMMDD and I would like to convert it to the following format but it is failing with an error:
2019-07-23 00:00:00.000
Conversion failed when converting date and/or time from character string
Here is the statement I'm using:
convert(varchar(10), convert(datetime, InstallDate0), 23)
The real problem is the choice of your datatype. varchar is the wrong choice. As a result, it seems that you now have some rows where the value of the "date" has been lost, as it can't be converted to a date.
To properly fix this problem, fix your datatype. Firstly I would create a new column to store the bad values:
ALTER TABLE YourTable ADD BadDate varchar(20); --as it's yyyyMMdd you don't need more than 8 characters, but we'll assume you have some really bad values
UPDATE YourTable
SET BadDate = InstallDate0
WHERE TRY_CONVERT(datetime,InstallDate0) IS NULL;
Now that you've done that, time to update the existing column:
UPDATE YourTable
SET InstallDate0 = CONVERT(varchar(8),TRY_CONVERT(datetime, InstallDate),112);
This'll set every value to the yyyyMMdd format where the value can be converted. NOw you can alter your table:
ALTER TABLE YourTable ALTER COLUMN InstallDate0 date; --AS it's yyyyMMdd, it seems silly to actually use datetime
Now you have a proper datetime column.
You'll then need to inspect the values of BadDate and try to correct them (or admit that any information they held has been lost for ever).
If you "must" have another column with the format, then add a further column:
ALTER TABLE YourTable ADD InstallDate0_f AS CONVERT(varchar(23),InstallDate0,121);
You can determine where the problems are using TRY_CONVERT(). The problem would seem to be the conversion to a datetime, so try this:
select InstallDate0
from t
where try_convert(datetime, InstallDate0) is null;
I have one column LogDate which is varchar(2000) type. I want this column as date type. Current table format 2014-03-31 09:13:03.000.
How can I do that?
I presume you are using SQL Server:
declare #LogDate varchar(2000)
set #LogDate = '2014-03-31 09:13:03.000'
select convert (datetime, #LogDate, 21)
Full table query at: http://sqlfiddle.com/#!3/58a3f/1/0
If all the records in the table having data in correct format(i.e all are date only, no characters) then you can directly alter the column data type to DATE type:
ALTER TABLE <table name> ALTER COLUMN LogDate date
I have a table, in TSQL, with a field containing data in YYYYMMDD format saved as varchar(50);
I want to add a date type column to the table for each of the corresponding records in this field.
Any ideas?
Assuming that you have stored correct format of date in your field (eg you don't have '20121433'), this script should works for you:
ALTER TABLE your_table
ADD your_field_Date DATETIME
UPDATE your_table
SET your_field_Date = CONVERT(DATETIME, your_field_varchar, 112)
ALTER TABLE your_table DROP COLUMN your_field_varchar
I am relatively new to SQL Server so I was wondering how to convert the data type from varchar to date format? I have a few thousands records so I need a query to help to convert the varchar to date in a single query.
I have the date in this format: yyyymmdd, in varchar(8) and I want to convert this into yyyymmdd, in date format.
Is there any queries to help me with this?
For various conversions between VARCHAR and DATETIME have a look at this link.
Actually in your case, since your VARCHAR is in yyyymmdd format, you could just:
convert(datetime, YourVarcharDateField, 112)
Simply Use this Inbuilt CONVERT Function, and Check this Link for formatting Dates
-- Use 101 if you have divider in your date
SELECT convert(datetime, '2014-01-02',101) as [DateTime]
-- Use 112 if you don't have divider in your date
SELECT convert(datetime, '20140131',112) as [DateTime]
Edited:
UPDATE yourTable SET field = convert(datetime, 'yourFieldName',112)
--This will update all of your field regardless of any particular row
--If you want to update any particular set of rows use `WHERE` clause
if you have more various formats goto to the given link.
Data types can be converted either implicitly or explicitly.
Implicit conversions are not visible to the user. SQL Server automatically converts the data from one data type to another. For example, when a smallint is compared to an int, the smallint is implicitly converted to int before the comparison proceeds.
Explicit conversions use the CAST or CONVERT functions.
The CAST and CONVERT functions convert a value (a local variable, a column, or another expression) from one data type to another
convert(datetime, '2013-05-04',101)
CAST ( expression AS data_type )
ALTER TABLE [dbo].[table] ADD ConvertedDate Date
UPDATE [dbo].[SysData] SET ConvertedDate = CAST(VarCharDate as Date)
ALTER TABLE [dbo].[table] DROP COLUMN VarCharDate
Use CAST OR CONVERT function to convert string to date
Try this:
SELECT CAST('20140102' AS DATE) AS convertedDate;
SELECT CAST(colName AS DATE) AS convertedDate FROM tableA; -- Replace column name and table name
OR
SELECT CONVERT(DATE, '20140102', 112) AS convertedDate;
SELECT CONVERT(DATE, colName, 112) AS convertedDate FROM tableA; -- Replace column name and table name
OUTPUT of both queries:
|convertedDate|
|-------------|
|2014-01-02 |
In SQL SERVER, there are two types of built in conversion techniques.
Convert
Cast
Convert having its own defaults so it will be outdated in upgraded version of SQL SERVER
better make use of CAST Conversion technique
In your scenario.Already having the date with datatype of Varchar(8) trying to Convert into Date
Solve in systematic manner.
Adding the one new Column in the existing table.
Alter Table Table_name Add changedDataTypeDate Date
Update the values in varchar datatype to Date Datatype
UpDate Table_name Set ChangedDataTypeDate = CAST(OriginalDataTypeDate as Date)
Again change the new column name into old column name.
Sp_Rename 'Tablename.changedDataTypeDate','OriginalDataTypeDate','COLUMN'
Its done.
Based on u r requirement.
Alter Table customer Add Purchase_Changedtype Date
Update Customer set Purchase_changedtype = CAST(Purchase_date as Date)
(If u need Time also replace Datetime istead of Date)
Alter table Customer Drop column Purchase_date
Sp_Rename 'Customer.Purchase_ChangedType','Purchase_Date','Column'