SQL 将 nvarchar 转换为 int

Question

I have a lot of '1.0' values of type nvarchar(max). I would like to convert\cast them to int but below queries:

  SELECT CONVERT(int, Quantity)
  FROM MyTable

or

 SELECT CAST(Quantity as int)
  FROM MyTable

or

 ALTER TABLE MyTable
  ALTER COLUMN [Quantity] int;

returns error message: Conversion failed when converting the nvarchar value '1.0' to data type int.

How to convert nvarchar '1.0' to int?

Answer 1

Set the value to an appropriate format first:

update mytable
    set quantity = convert(decimal, quantity)
    where quantity like '%.%';

Then do the alter table .

Here is a db<>fiddle using SQL Server.