ASP.NET PDF Viewer using C#, VB/NET

Perhaps the simplest way to implement optimistic locking is to save old values of the data to be modified (say, in hidden form fields) when we select the record that needs to be updated When issuing the actual update, we include the old column values in the where clause, as shown in the following pseudo code: update table_name set col1 = :new_col1_value, col2 = :new_col2_value where col1 = :old_col1_value and col2 = :old_col1_value and primary_key_col1 = :primary_key_col1 and primary_key_col2 = :primary_key_col2 If the columns being modified have not been changed by any other transaction, the update would successfully change the record On the other hand, if another transaction updated any of the values that your transaction is modifying, the update would affect zero rows You can detect this in your application code and ask the user to retry her transaction.

barcode font excel free, free barcode font for excel 2003, barcode inventory excel program, free qr barcode font for excel, barcode add in for excel 2013, free barcode generator software excel, barcode in excel 2003, free barcode font for excel 2007, any size barcode generator in excel free to download, excel2010 microsoft barcode control 9.0,

Deploy an ASMX file pointing at the .NET class type containing any WebMethod attributes on class method (or on methods of interfaces implemented in the class).

Pattern matching can be used to decompose structured values. Here is an example where we match nested tuple values: let highLow a b = match (a,b) with | ("lo", lo), ("hi", hi) -> (lo,hi) | ("hi", hi), ("lo", lo) -> (lo,hi) | _ -> failwith "expected a both a high and low value";; The match examines two pairs and looks at the strings in the first element of each, returning the associated values: > highLow ("hi",300) ("lo",100);; val it : int * int = (100,300) The first rule matches if the first parts of the input pairs are the strings "lo" and "hi", respectively. It then returns a pair made from the respective second parts of the tuples. The second rule is the mirror of this in case the values appeared in reverse order. The final cases of both of the previous examples use wildcard patterns to cover remaining cases. This makes the patterns exhaustive. Frequently, no wildcard is needed to ensure this, because for many input types F# is able to determine whether the given set of rules is sufficient to cover all possibilities for the given shape of data. However, if a match is not exhaustive, a warning is given: > let urlFilter3 url agent = match url,agent with | "http://www.control.org", 86 -> true | "http://www.kaos.org", _ -> false;; match url,agent with ^^^^^^^^^^^^^^^^^^^^ warning: Incomplete pattern match. In these cases, it may be necessary to add an extra exception-throwing clause to indicate to the F# compiler that the given inputs are not expected: let urlFilter4 url agent = match url,agent with | "http://www.control.org", 86 -> true | "http://www.kaos.org", _ -> false | _ -> failwith "unexpected input" Nonexhaustive matches are automatically augmented by a default case where a MatchFailureException is thrown. We discuss exceptions in 4.

For example, if some other transaction changed the value of the column col1 in the preceding pseudo code, then the update would not affect any rows since the where clause criterion col1 = :old_col1_value would not be met Let s look at an example Consider the following package, opt_lock_save_old_val_demo, which demonstrates this technique of implementing optimistic locking: scott@ORA10G> create or replace package opt_lock_save_old_val_demo 2 as 3 procedure get_emp_details( p_empno in number, p_ename in out varchar2, 4 p_sal in out number ); 5 procedure update_emp_info( p_empno in number, p_old_ename in varchar2, p_old_sal in number, p_new_ename in varchar2, p_new_sal in number, p_num_of_rows_updated in out number ); 6 end; 7 / Package created The definition of the package follows, along with an explanation of the two package procedures The first procedure, get_emp_details, gets the employee name and salary the two columns that can be modified by the end user.

F# is frequently able to determine whether pattern-matching rules are redundant, such as if a rule can never be selected because previous rules subsume all such cases. In this case, a warning is given. For example: > let urlFilter2 url agent = match url,agent with | "http://www.control.org", _ -> true | "http://www.control.org", 86 -> true | _ -> false;; | "http://www.control.org", 86 -> true ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ warning: This rule will never be matched.

You can use the COM SOAP stack to expose these as Web Services. You could also use ASMX and an interop assembly to expose them via IIS.

This query is executed to display the record that the user chose to modify (notice that we don t lock the record):.

Tip Use wildcard patterns with care. F# can often determine whether a match is exhaustive, and the use