I'd like alter a column type from Datetime to float. Hence, I executed the below query but it was getting a issue
alter table dbo.purchasedate
alter column supp_dt float null
Error :: Implicit conversion from data type datetime to float is not allowed. Use the CONVERT function to run this query.
Without knowing your desired output, you could just: Add Float column, populate, drop date column.
To my knowledge you cannot add a CONVERT to an ALTER statement, anyone know otherwise?
Related
I am trying to change a column's datatype. The column of type VARCHAR has thousands of GUID values like look those shown below:
b1f4ff32-48d4-494e-a32c-044014cea9
bc5a1158-b310-49ff-a1f3-09d4f8707f69
4b7ebc9d-9fa1-42d9-811e-0b7b4b7297a
fc7ba848-98ea-4bc6-add7-11f0ee9c6917a21
485741ff-2ab2-4705-91b3-136389948b7c
I need to convert the column type to unqiqueidentifier using the script below. Can I do that safely without corrupting the column data?
alter table MyTable
alter column guidColumn uniqueidentifier not null
If you change the data type SQL Server will first check if all the values in the columns can be implicitly converted to the new data type; if they cannot then the ALTER will fail. If they can, then they will be implicitly converted and the ALTER will be successful (assuming no dependencies of course).
For a uniqueidentifier then either it's a valid value or it's not, so either the data will all convert or the ALTER won't take place. For something like a date and time data type, however, you could very easily end up with incorrect data if the data is stored in an ambiguous format like dd/MM/yyyy. This could mean a value like '12/05/2022' ends up being stored as the date value 2022-12-05 rather than 2022-05-12. For such scenarios you would therefore want to UPDATE the data to an unambiguous format first, and then ALTER the data type of the column.
The uniqueidentifier type is considered a character type for the purposes of conversion from a character expression, and therefore is subject to the truncation rules for converting to a character type.
Also there are limitations, uniqueidentifier type is limited to 36 char
So if you decide to truncate the table like in this example:
DECLARE #ID NVARCHAR(max) = N'0E984725-C51C-4BF4-9960-E1C80E27ABA0wrong';
SELECT #ID, CONVERT(uniqueidentifier, #ID) AS TruncatedValue;
This will be the result:
String
Truncated Value
0E984725-C51C-4BF4-9960-E1C80E27ABA0wrong
0E984725-C51C-4BF4-9960-E1C80E27ABA0
So, if your string is more or less than 36 it will not truncate correctly.
For more information check Microsoft documentation:
https://learn.microsoft.com/en-us/sql/t-sql/data-types/uniqueidentifier-transact-sql?view=sql-server-ver15
I am trying to convert data type of one of my columns (the table was imported from Excel), and then it shows an error
Error converting data type nvarchar to float
Code:
ALTER TABLE [dbo].[games_activity_2020$]
ALTER COLUMN [Version] float
What can I do differently?
probably there might be any character values inserted in the table while importing from excel. You can check those values using the below query
SELECT version
from [dbo].[games_activity_2020$]
where TRY_CONVERT(float, version) IS NULL
you can update those values and try to ALTER the table again
I suggest you run
SELECT * FROM [dbo].[games_activity_2020$]
WHERE TRY_CAST([Version] as FLOAT) IS NULL
and fix up any problematic values
I have a database table of that I have used to store the data returned from a web spider. I have a column that contains ticket prices for different events all in the varchar type (as the scrapy spider has to scrape the data in unicode). I'm trying to return the min price of the column and since the min() function only works for data of type INT, I tried to convert the column to integers using a solution from this SO post:
ALTER TABLE vs_tickets ALTER COLUMN ticketprice TYPE integer USING (ticketprice::integer);
but I got the error: ERROR: invalid input syntax for integer:
I also tried: change_column :vs_tickets, :ticketprice, 'integer USING CAST(ticketprice AS integer)' but that didn't work either.
What is the proper way to convert the column to type INT?
Edit:
You have decimal places in the string, so a simple cast is not going to work. You can do a double conversion:
cast(cast(ticketprice as decimal(10, 2)) as int)
or:
(ticketprice::decimal(10, 2))::int
(The parens are not strictly necessary.)
EDIT:
Or, as Erwin points out, just use numeric:
(ticketprice::numeric)::int
Postgres is much smarter about numeric than most other databases . . . after all, it supports numbers that are egregiously large ;)
The final query is:
ALTER TABLE vs_tickets
ALTER COLUMN ticketprice TYPE integer USING (ticketprice::numeric::integer);
I'm going to bet on your column have wrong characters.
Also you may want use float or numeric because you will lose decimals if convert to integers.
You need create a function to check if a text is numeric like this isnumeric-with-postgresql
Then check each row like this
select ticketprice
from vs_tickets
where ISNUMERIC(ticketprice) = false;
As your comment you also should try
SELECT ticketprice::float
You will be best off adding an INT column, moving your data with a cast and then removing the old varchar column.
ALTER TABLE vs_tickets ADD COLUMN ticketprice_int TYPE int;
GO
update vs_tickets SET ticketprice_int = cast(ticketprice as int);
// if you fail to cast the varchar to int you can use Gordon's method
// update vs_tickets SET ticketprice_int = cast(cast(ticketprice as decimal(10, 2)) as int);
GO
ALTER TABLE vs_tickets DROP COLUMN ticketprice;
GO
ALTER TABLE vs_tickets RENAME COLUMN ticketprice_int to ticketprice;
GO
With this at minimum you will be able to tell if and where a cast/convert fails and be able to check and recheck at each step before you can't turn back.
I have a procedure which takes a date value as parameter and then inserts the date value in a table:
CREATE PROCEDURE dbo.procInsert
#employed_on DATE
AS
BEGIN
INSERT INTO dbo.TBL(EMPLOYED_ON)
VALUES(#employed_on)
END
however i am getting this error:
Implicit conversion from data type varbinary to date is not allowed.
Use the CONVERT function to run this query.
I tried to use convert but its not working.
UPDATE
i found my mistake. i swapped the variables for insert.
i found my mistake. i swapped the variables for insert.
I don't have that much experience with writing SQL queries and I have hit upon a problem. I have read in a table of data into a temporary table (#Temp_Results) and need to change the format of various columns before moving the data to the end table.
What Im trying to do below is take a column (Oil2) that is an nvarchar and convert it to a tinyint and put the result into a new column (Oil4) then drop Oil2 - I realise I will loose decimal places but thats not a problem. The CASE statement is designed to capture anything that is not a number, seeing as the original datatype is nvarchar there could be anything in there and I'm only interested in the numbers.
However when I run the code I get 'Error converting data type nvarchar to float' pointing towards the 'UPDATE' line of code and I cant figure out how to get round it.
Can any of you guys spot my rookie mistake?
ALTER TABLE tempdb..#Temp_Results /*Add new column with datatype of tinyint*/
ADD Oil4 tinyint
GO
UPDATE tempdb..#Temp_Results
SET tempdb..#Temp_Results.Oil4 = CASE
WHEN ISNUMERIC(tempdb..#Temp_Results.Oil2)=1
THEN CAST(ROUND(CAST(tempdb..#Temp_H_Results.Oil2 as float), 0) AS tinyint)
ELSE NULL
END
ALTER TABLE tempdb..#Temp_H_Results /*Drop redundant column of data in wrong (nvarchar) format*/
DROP COLUMN Oil2
Go
Try casting to Decimal in stead of float
CONVERT(varchar(28), cast(tempdb..#Temp_H_Results.Oil2 as decimal(28,0)))