Best way to store program state variables in SQL Server

Question

I'm writing an app in C# that connects to a SQL Server using Entity Framework. Every instance of the app shares the tables and some variables (ints, strings and bools).

What's the best way to share that variables (int string and bools) via tables in SQL Server?

Since tables have fixed type columns, one table would not do it without loosing type-safe in C#, because every type should be converted to string or boxed to object.

The two solutions I came up with are, one table with 3 columns ( int , varchar , bool ), with the data writing in the appropriately typed column, or 3 tables with one column.

Or maybe I am totally missing the point here..

The question would be: what's the most elegant way to accomplish saving typed data to a SQL Server?

Answer 1

You can use SQL_Variant for that purpose

https://docs.microsoft.com/en-us/sql/t-sql/data-types/sql-variant-transact-sql?view=sql-server-2017

CREATE   TABLE tableA(colA sql_variant, colB int)  
INSERT INTO tableA values ( cast (46279.1 as decimal(8,2)), 1689)  
SELECT   SQL_VARIANT_PROPERTY(colA,'BaseType') AS 'Base Type',  
         SQL_VARIANT_PROPERTY(colA,'Precision') AS 'Precision',  
         SQL_VARIANT_PROPERTY(colA,'Scale') AS 'Scale'  
FROM      tableA  
WHERE      colB = 1689