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# Wednesday, February 06, 2008

This tutorial explains how to design a beautiful form (Facebook inspired) using a clean CSS design with only <label> and <input> tags to simulate an HTML <table> structure. You can reuse all CSS/HTML elements to design your custom form for your web projects:


Live preview Download this tutorial (HTML + CSS)

Update: I solved an issue with Safari and Firefox, download the new zip file.

Step 1: Input elements and labels
When you design a form (for example to Sign-in or Sign-up on your site), a fast solution to place all form elements in a page is add them into the table's cells. A good and simple alternative is using HTML <input> and <label> tags in this way:

<label>
<span>
Full name</span>
<input type="text" class="input-text" name="email" id="email"/>
</label>


...and the css code is the following:

div.box .input-text{
border:1px solid #3b6e22;
color:#666666;
}

div.box label{
display:block;
margin-bottom:10px;
color:#555555;
}

div.box label span{
display:block;
float
:left;
padding-right:6px;
width:70px;
text-align:right;
font-weight:bold;
}


...in this way, <span> element inside the <label> tag set the same width (70px) for the field descriptions to the left of each <input> element in your form, like if field description and input was placed in a table row with two horizontal cells.

Update: to solve an issue with Safari (using size attribute) and with Firefox (problem to display correctly input label) I changed the following code:

div.box label span{
display:inline-block;
...
}


with:

div.box label span{
display:block;
float
:left;
...
}



Step 2: Submit Button
When you add a standard/unstyled button in a form (<input> or <button> tag) take a mind it looks different on different browser and OS. A good practice to uniform how it looks is to define a CSS class to apply to your button. Instead of <input> or <button> tag you can also use a simple link (<a> tag) like in this case (I designed and applyed "green" class to the link <a>):

<a href="#" onClick="javascript:submit()" class="green">
Sign in
</a>


...and CSS code for the "green" class is the following:

.green{
background:url(img/green.gif);
padding:0px 6px;
border:1px solid #3b6e22;
height:24px;
line-height:24px;
color:#FFFFFF;
font-size:12px;
margin-right:10px;
display:inline-block;
text-decoration:none;
}


The final result is very nice and clean, ready to reuse in your projects.

Download this tutorial (HTML + CSS)

Wednesday, February 06, 2008 4:56:56 PM (Jerusalem Standard Time, UTC+02:00)  #    Comments [0] - Trackback
CSS | Web Design
# Tuesday, February 05, 2008

Working as a team against a common database schema can be a real challenge. Some teams prefer to have their local code connect to a centralized database, but this approach can create many headaches. If I make a schema change to a shared database, but am not ready to check in my code, that can break the site for another developer. For a project like Subtext, it is just not feasible to have a central database.

Instead, I prefer to work on a local copy of the database and propagate changes via versioned change scripts. That way, when I check in my code, I can let others know which scripts to run on their local database when they get latest source code. Of course this can be also be a big challenge as the number of scripts starts to grow and developers are stuck bookkeeping which scripts they have run and which they haven’t.

That is why I always recommend to my teams that we script schema and data changes in an idempotent manner whenever possible. That way, it is much easier to simply batch updates together in a single file (per release for example) and a developer simply runs that single script any time an update is made.

As an example, suppose we have a Customer table and we need to add a column for the customer’s favorite color. I would script it like so:

IF NOT EXISTS 
(
    SELECT * FROM [information_schema].[columns] 
    WHERE   table_name = 'Customer' 
    AND table_schema = 'dbo'
    AND column_name = 'FavoriteColorId'
)
BEGIN
    ALTER TABLE [dbo].[Customer]
    ADD FavoriteColorId int
END

This script basically checks for the existence of the FavoriteColorId column on the table Customer and if it doesn’t exist, it adds it. You can run this script a million times, and it will only make the schema change once.

You’ll notice that I didn’t query against the system tables, instead choosing to lookup the information in an INFORMATION_SCHEMA view named Columns. This is the Microsoft recommendation as they reserve the right to change the system tables at any time. The information views are part of the SQL-92 standard, so they are not likely to change.

There are 20 schema views in all, listed below with their purpose (aggregated from SQL Books). Note that in all cases, only data accessible to the user executing the query against the information_schema views is returned.

Name Returns
CHECK_CONSTRAINTS Check Constraints
COLUMN_DOMAIN_USAGE Every column that has a user-defined data type.
COLUMN_PRIVILEGES Every column with a privilege granted to or by the current user in the current database.
COLUMNS Lists every column in the system
CONSTRAINT_COLUMN_USAGE Every column that has a constraint defined on it.
CONSTRAINT_TABLE_USAGE Every table that has a constraint defined on it.
DOMAIN_CONSTRAINTS Every user-defined data type with a rule bound to it.
DOMAINS Every user-defined data type.
KEY_COLUMN_USAGE Every column that is constrained as a key
PARAMETERS Every parameter for every user-defined function or stored procedure in the datbase. For functions this returns one row with return value information.
REFERENTIAL_CONSTRAINTS Every foreign constraint in the system.
ROUTINE_COLUMNS Every column returned by table-valued functions.
ROUTINES Every stored procedure and function in the database.
SCHEMATA Every database in the system.
TABLE_CONSTRAINTS Every table constraint.
TABLE_PRIVILEGES Every table privilege granted to or by the current user.
TABLES Every table in the system.
VIEW_COLUMN_USAGE Every column used in a view definition.
VIEW_TABLE_USAGE Every table used in a view definition.
VIEWS Every View

When selecting rows from these views, the table must be prefixed with information_schema as in SELECT * FROM information_schema.tables.

Please note that the information schema views are based on a SQL-92 standard so some of the terms used in these views are different than the terms in Microsoft SQL Server. For example, in the example above, I set table_schema = 'dbo'. The term schema refers to the owner of the database object.

Here is another code example in which I add a constraint to the Customer table.

IF NOT EXISTS(
    SELECT * 
    FROM [information_schema].[referential_constraints] 
    WHERE constraint_name = 'FK_Customer_Color' 
      AND constraint_schema = 'dbo'
)
BEGIN
  ALTER TABLE dbo.Customer WITH NOCHECK 
  ADD CONSTRAINT
  FK_Customer_Color FOREIGN KEY
  (
    FavoriteColorId
  ) REFERENCES dbo.Color
  (
    Id
  )
END

I generally don’t go to all this trouble for stored procedures, user defined functions, and views. In those cases I will use Enterprise manager generate a full drop and create script. When a stored procedure is dropped and re-created, you don’t lose data as you would if you dropped and re-created a table that contained some data.

With this approach in hand, I can run an update script with new schema changes confident that I any changes in the script that I have already applied will not be applied again. The same approach works for lookup data as well. Simply check for the data’s existence before inserting the data. It is a little bit more work up front, but it is worth the trouble and schema changes happen less frequently than code or stored procedure changes.

Tuesday, February 05, 2008 11:57:38 AM (Jerusalem Standard Time, UTC+02:00)  #    Comments [0] - Trackback
Programming | SQL

Some developers love working with relational databases, and other developers can't stand to touch them. Either way - if your application uses a database, you have to treat the database with some respect. The database is as much a part of an application as the code and the models inside the software.

Here are three rules I've learned to live by over the years of working with relational databases.

1. Never use a shared database server for development work.

Fossil!The convenience of a shared database is tempting. All developers point their workstations to a single database server where they can test and make schema changes. The shared server functions as an authoritative source for the database schema, and schema changes appear immediately to all team members. The shared database also serves as a central repository for test data.

Like many conveniences in software development, a shared database is a tar pit waiting to fossilize a project. Developers overwrite each other's changes. The changes I make on the server break the code on your development machine. Remote development is slow and difficult.

Avoid using a shared database at all costs, as they ultimately waste time and help produce bugs.

2. Always Have a Single, Authoritative Source For Your Schema

Ideally, this single source will be your source control repository (see rule #3). Consider the following conversation:

Developer 1: It's time to push the app into testing. Do we copy the database from Jack's machine, or Jill's machine?

Developer 2: Ummmmmmmm, I don't remember which one is up to date.

Developer 1: We're screwed.

Everyone should know where the official schema resides, and have a frictionless experience in getting a fresh database setup. I should be able to walk up to a computer, get the latest from source control, build, and run a simple tool to setup the database (in many scenarios, the build process can even setup a database if none exists, so the process is one step shorter).

How you put your database into source control depends on your situation and preferences. Any decent O/R mapping tool should be able to create a database given the mappings you've defined in a project. You can also script out the database as a set of one or more files full of SQL DDL commands. I generally prefer to keep database views and programmatic features (including functions, triggers, and stored procedures) as separate files - but more on this in a later post.

There are plenty of tools to help. Leon Bambrick has a long list (albeit one year old list) of tools and articles that can help, while Jeff Atwood gushes over the virtues of Visual Studio for Database Professionals.

3. Always Version Your Database

There are many ways to version databases, but the common goal is to propagate changes from development, to test, and ultimately to production in a controlled and consistent manner. A second goal is to have the ability to recreate a database at any point in time. This second goal is particularly important if you are shipping software to clients. If someone finds a bug in build 20070612.1 of your application, you must be able to recreate the application as it appeared in that build - database and all.

In a future post, I'll describe an approach I've used for database versioning that has worked well for many years of commercial development.

In the meantime, if you are looking for more database rule, then Adam Cogan and SSW maintain an excellent list.

Tuesday, February 05, 2008 11:35:24 AM (Jerusalem Standard Time, UTC+02:00)  #    Comments [0] - Trackback
Programming | SQL
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Guy Levin
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