Sudoku solver

There is currently  of different Sudokus in the database.
The easiest Sudoku has difficulty .
The hardest Sudoku has difficulty .
Step 1
Feed grid
 =  Number from 1 to 
 = 
         Example of string:  39...8...1..7..3...5..6..8...6.94..2.........5..68.4...7..1..4...4..2..5...8...71
... or fill the grid manually.
Step 2
Check Sudoku validity
 
Step 3
Check out the grid
A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified)
  1 2 3 4 5 6 7 8 9
A
 
 
 
 
 
 
 
 
 
B
 
 
 
 
 
 
 
 
 
C
 
 
 
 
 
 
 
 
 
D
 
 
 
 
 
 
 
 
 
E
 
 
 
 
 
 
 
 
 
F
 
 
 
 
 
 
 
 
 
G
 
 
 
 
 
 
 
 
 
H
 
 
 
 
 
 
 
 
 
I