         case add(ColumnDefinition)
         case addColumnLiteral(SQL)
         case rename(old: String, new: String)
+        case drop(String)
     }
     
     private var alterations: [TableAlterationKind] = []

    
    private func _rename(column name: String, to newName: String) {
        alterations.append(.rename(old: name, new: newName))
    }
    
    fileprivate func sql(_ db: Database) throws -> String {

                chunks.append(newName.quotedDatabaseIdentifier)
                let statement = chunks.joined(separator: " ")
                statements.append(statement)
                
            case let .drop(column):
                var chunks: [String] = []
                chunks.append("ALTER TABLE")
                chunks.append(name.quotedDatabaseIdentifier)
                chunks.append("DROP COLUMN")
                chunks.append(column.quotedDatabaseIdentifier)
                let statement = chunks.joined(separator: " ")
                statements.append(statement)
            }
        }
        
