SQL Server-根据提供的值验证表列的值

Question

I have the following task that want to solve using SQL Server's query and/or stored procedure, and I would really appreciated if someone can give me some directions.

Basically we have a data warehouse based on SQL Server. I want to validate columns in certain tables to ensure the values in these columns are valid.

Example as below:

Table1 ColumnsToValidate specifies the table/columns in which values need to be validated. In the example I want to validate the Gender column of the Customer table, and the State column of the Address table. And the validationID is a foreign-key to a table holding all the valid values ( Table2 ).

Table2 ValidationValues : this table holds all valid values for specific validation rules. In the example, validation rule #1 ( ValidationID = 1 ) has two valid values, and validation rule #2 specified 3 valid values.

I'd like to (using SQL) dynamically create a query based on values in Table 1, which accordingly selects the Customer.Gender column and the Address.State column, so the values in these columns can be validated against the values in Table 2.

Table1: ColumnsToValidate

TableName  |   ColumnName   |  ValidationID
-----------+----------------+-----------------
Customer   |    Gender      |   1       
Address    |    State       |   2       

Table2: ValidationValues

ValidationID | Values  
-------------+----------------
1            | Male      
1            | Female       
2            | NY      
2            | WA        
2            | CA      

Table3: Customer

CustomerID | Gender  
-----------+----------------
111        | Male      
112        | Female       
113        | Unknown      
114        | NULL    

Table4: Address

AddressID  | State   
-----------+----------------
211        | AL      
212        | NY       
213        | WA      
214        | NULL        

EDIT: I could write this in a C# program, but the program will be slow. I would think there could be a way in pure SQL (SQL Server)

Answer 1

Here is my solution, in two steps -

1) To validate the values "as if" the target table and column are known, eg the following outer join query finds invalid values on the Customer.Gender column.

select * from Customer a
left join ValidationValues b
on a.Gender = b.values
and a.ValidationID = b.ValidationID 
where b.values is null

2) Use dynamic-SQL to generate above SQL script, using values from table ColumnsToValidate , substituting table-name 'Customer' and column-name 'Gender' with variables @tab and @col1 :

declare @tableCursor cursor,
        @tab varchar(100),
        @col1 varchar(100),
        @val_id varchar(20)

set @tableCursor = cursor for select * from ColumnsToValidate

open @tableCursor
fetch next from @tableCursor into @tab, @col1, @val_id
while(@@fetch_status = 0)
begin
    --dynamic sql
    declare @sql varchar(max)

    set @sql = 

    N'select * from '+ @tab +' a ' +
    N'left join ValidationValues b ' +
    N'on a.' + @col1 + ' = b.values ' +
    N'and a.' + @val_id + ' = b.ValidationID ' +
    N'where b.values is null'

    --print @sql
    exec @sql

    fetch next from @tableCursor into @tab, @col1, @val_id
end

close @tableCursor
deallocate @tableCursor

As being said, these are mock-up codes and they are not tested. However I'd just to share the ideas to people having similar problems - the key to the solution is "Dynamic SQL".