Wednesday, 26 August 2009

"The path is not of a legal form."

If you attempt to open your project (standard windows application) and the designer gives you a similar error to the one below....

"One or more errors encountered while loading the designer. The errors are listed below. Some errors can be fixed by rebuilding your project, while others may require code changes."

The the problem is that the form's designer is trying to locate one of the types referenced by your form and is unable.
This means that your project probably wasn't built since the reference was added or that the project file has somehow been changed.

If building the solution doesn't work, try going over the references in the project and looking at where their locations are and verifying that they all actually exist.

UML relationships

I've had this post-it note on my desk for a while now, its a nice nudge in the right direction if you havent done any UML for a while.

Stop Postback in .NET

For example, if i had an ImageButton object and I would like some Javascript to execute upon clicking this control, I would add the JS on code behind like so...

btnViewParts.Attributes.Add("OnClick","ViewParts(); return false;");

The return false; Portion of this code prevents the postback.

Tuesday, 25 August 2009


Here are some of the differences between Oracle's PL/SQL and SQL Server's T-SQL.

OracleSQL ServerMore Information
%TYPE data typeNo equivalent

The %TYPE data type of Oracle, lets you create a variable and have that variable's data type be defined by a table or view column or a PL/SQL package variable.

There is no equivalent for Oracle's %TYPE datatype in T-SQL, but it can be simulated (not very conveniently though) using User Defined Data types (UDT). Here is an example:

EXEC sp_addtype 'MyType', 'smallint', NULL

CREATE TABLE MyTable (i MyType)


BEFORE triggersINSTEAD OF triggers

Use INSTEAD OF trigger in SQL Server as an equivalent to Oracle's BEFORE trigger.

For more information on INSTEAD OF triggers, see SQL Server Books Online

DECODE() functionCASE expression

DECODE can be conveniently simulated using the T-SQL CASE expression. Here's an example:

CASE Sport
WHEN 'Cricket' THEN 'England'
WHEN 'Hockey' THEN 'India'
WHEN 'Base Ball' THEN 'America'
END AS 'Originating Country'
FROM Sports

DESCRIBEsp_help or sp_columns

There are a lot of alternatives for Oracle's DESCRIBE, in SQL Server. You could use the system stored procedure sp_help for detailed information about a table's columns and other properties.

If sp_help is providing you with too much information, then try the ODBC catalog stored procedure, sp_columns.

There are a bunch of other useful sp_help* stored procedures available in SQL Server. You can find more information about those in SQL Server Books Online.

If none of those procedures are suitable for your requirements, then you could query the system view INFORMATION_SCHEMA.COLUMNS, to get the desired information. You could wrap your code inside a stored procedure named DESCRIBE, if you wish.

As a last resort, you could even query system tables like sysobjects and syscolumns, but this is not a recommended approach.

DUAL tableNo equivalent

There is no DUAL table in SQL Server. In fact, you don't need one in SQL Server, as you can have a SELECT statement without a FROM clause.

For example, consider the following SELECT statement in Oracle:

SELECT 'Something'

In SQL Server, the same result can be obtained by the following command:

SELECT 'Something'

If you are porting some code from Oracle into SQL Server and if you don't want to remove all references to DUAL table, then just create a DUAL table in your database using the following commands:

DUMMY varchar(1)


INTERSECT operatorNot supported

Use EXISTS clause to generate the same result.

The following example illustrates the simulation of Oracle's INTERSECT operator:

SELECT OrderID, OrderDate
FROM Orders O
FROM RefundsTable R
WHERE O.OrderID = R.OrderID

MINUS operatorNot supported

Use NOT EXISTS clause in your SELECT statement to generate the same result.

The following example illustrates the simulation of Oracle's MINUS operator:

SELECT OrderID, OrderDate
FROM Orders O
FROM RefundsTable R
WHERE O.OrderID = R.OrderID

Nested tablesNot supported

Oracle 8i and prior versions didn't support this feature and is introduced in Oracle 9i. This feature basically enables you to store a table, within a column. It is like having an array of records in your database columns.

SQL Server has no concept of nested tables.

As a workaround, You could store your sub-tables or child tables in the form of XML inside a char, nchar, varchar, nvarchar, text or ntext type column, and parse it as needed, at runtime. See OPENXML, sp_xml_preparedocument, sp_xml_removedocument in SQL Server 2000 Books Online.

Another possible workaround would be to store comma separated values (CSV).

Note that this is against the basic rules of normalization. Columns are nomore atomic, with nested tables.

From a design point of view, best thing to do would be, to create different tables for representing different entities and link them with primary and foreign key relationships. This will also make searching easier.

OracleSQL Server


PackagesNot supported

No equivalent in SQL Server for Oracle's Packages and Package variables concept


Every database product implements and extends the standard SQL. Oracle's implementation of SQL is called PL/SQL, while Microsoft's is called T-SQL (Transact-SQL)

Row level securityNo equivalent

Though there is no inbuilt support in SQL Server for row level permissions, you can implement it using view and system functions.

For more information and a working example, read this article:

Implementing row level permissions/security in SQL Server databases

rownum pseudo columnNo equivalent

Though there is no rownum or rowid in SQL Server, there are several ways in which a row number can be generated.

For some examples, read this article:

Q186133 INF: How to Dynamically Number Rows in a Select Statement


Use the locking hint UPDLOCK in your SELECT statement.

See SQL Server Books Online for more information.


It is much simpler in SQL Server to generate a sequence value for a primary key or a non-key column.

You just need to turn on the IDENTITY property of column. IDENTITY property can be set to columns of the following data types: tinyint, smallint, int, bigint, decimal, numeric

Try this example to see how it works:

i int IDENTITY(1, 1)
j int

INSERT INTO foo (j) VALUES (911)
INSERT INTO foo (j) VALUES (999)

SQL *PlusQuery Analyzer

For connecting to SQL Server and executing queries and modifying data, use the built-in Query Analyzer. It is much more powerful and friendlier than Oracle's SQL *Plus

START WITH...CONNECT BY clauseNo equivalent

Though there's no direct equivalent in T-SQL for Oracle's START WITH...CONNECT BY, there are several ways and efficient techniques for processing and querying hierarcical data.

For more information, read this article:

Working with hierarchical data in SQL Server databases


You can simulate Oracle Synonyms in SQL Server using Views. For example, the following creates a view that returns the OrderID and OrderDate from Orders table.

SELECT OrderID, OrderDate
FROM Orders

Now you can select data from the view, using the following SELECT statement:


The following example will create a view which is equivalent to Oracles TABS synonym or USER_TABLES data dictionary view (For simplicity, I am only including the table name in the view definition):

SELECT name AS table_name
FROM sysobjects
WHERE type = 'U'

Now you can execute the following SELECT statement to return all user table names:

SELECT table_name

Monday, 24 August 2009

Frame Locations...

self and window
These refer to the global object of current web page.

Refers to the window object of the page that is holding the current page in a frameset.

Refers to the window object of the page at the top of the frames hierarchy.

Refers to a frame or iframe held by the current page.