SQL 错误在视图中将 nvarchar 转换为数字

Question

I have the following table. The current column type of totalsales is (nvarchar(max), null) . The requirement is to change this column type to a numeric value in a SQL view.

I tried to do the following:

CAST([totalsales] AS numeric) AS [totalsales]

This statement doesn't work after I run the query on the view. Any suggestions? Many thanks!

Answer 1

Replace comma (,) with empty and then convert to numeric (assuming this column will always have only numeric values).

select id, totalsales as totalsales_nvarchar
 ,cast(replace(totalsales, ',','') as numeric) AS totalsales_numeric 
from tb1

Answer 2

Ok! Lets try this:

alter table <table_name> modify <column_name datatype>;

• for example: • Lets say we've created a table 'SAMPLE' with two columns 'ID' and 'NAME' having datatype as 'VARCHAR' each.(Here's the query)

  create table sample(id varchar(10), name varchar(20));

• But then we fond a flaw in it that the 'ID' column should have datatype as 'NUMBER'.

• Hence, we rectify our mistake by altering the table as==>>

alter table sample modify id number;

and when we describe table, now we have this; ID column perfectly carrying a datatype as 'NUMBER'

TABLE SAMPLE
Column  Null?   Type
ID       -      NUMBER
NAME     -      VARCHAR2(20)