How to dynamically provide column name and update the record in SQL Server?

Question

I have a table like this

I want to store column name in varibale @myColumn and then use Update command. How can this be done? Is it possible?

    DECLARE @myColumn varchar(20)
    SET @myColumn = 'State'
    UPDATE Country SET @myColumn = 'Florida' WHERE Id = 1

Answer 1

Yes, it's possible with some dynamic SQL. If you have complete control in the process, you can try this solution:

Let's create a temp table to show:

create table #temp ([id] int, [state] varchar(10));

Insert into #temp
SELECT 1 as ID, null as [state]

select * from #temp

Now that's created, let's try

DECLARE @myColumn varchar(20), @sql varchar(400)
SET @myColumn = '[state]'

set @sql = CONCAT('Update #temp SET ',@myColumn ,'= ''FLORIDA'' where ID = 1')

exec(@sql)

Check the results

select * from #temp

If you don't have complete control over the process, you need to save your code from SQL Injection.

Answer 2

To dynamically use the name of a column you'll need Dynamic SQL.

Here's an example:

 DECLARE @DynSql nvarchar(max), @DynParams nvarchar(max), @UpdateSql nvarchar(max), @UpdateParams nvarchar(max); DECLARE @myColumn varchar(20), @myColumnValue varchar(20), @myId INT; SET @UpdateSql = 'UPDATE Country '+CHAR(10) + 'SET [COLUMN] = @Value' + CHAR(10) + 'WHERE Id = @Id'; SET @UpdateParams = N'@Value varchar(20), @Id int'; SET @myColumn = 'State'; SET @myColumnValue = 'Florida'; SET @myId = 1; SET @DynSql = REPLACE(@UpdateSql, '[COLUMN]', QUOTENAME(@myColumn)); SET @DynParams = @UpdateParams; -- select @DynSql As DynSql; EXECUTE sp_executesql @DynSql, @DynParams, @Value = @myColumnValue, @Id = @myId;

 1 rows affected 

SELECT * FROM Country WHERE ID = 1;

ID	CountryName	State
1	United States of America	Florida

Demo on db<>fiddle here