Sometimes you need to create a limited user account in SQL Server 2005. This is a trivial task but I find many new DB developers struggling to do so. However, if you understand the underlying concept, it indeed is trivial.
This is how I find new DB developers creating a limited user account:
1. Open up SQL Server Management Studio
2. Expand the desired DB > Security
3. Right click on Users and select New User…
4. In the Database User – New dialog, enter in a User name following by a Login name. Usually both are the same
5. Bang. This is where you get the error “Error 15007 when trying to add a new user”
So what went wrong in the above steps? The answer is that you cannot create a User Role without first creating a Login. A Login connects to an SQL Server instance while a User Role defines the database access level. In other words:
Login – SQL Server Level
User – Database Level
Now to create a limited user account, you following steps have to be followed:
1. Open up SQL Server Management Studio
2. Expand Security. You will see a Logins node. Right click on Logins and click on New Login…
3. In the Login – New dialog, enter in a Login name
4. Next click on SQL Server Authentication radio button. Enter and confirm Password.
5. From Default database, select the desired database. Now you are done creating a Login. The next step is to create his specific role
6. Under the SQL Server instance node, Expand Databases > [Database] > Security. You will see a Users node.
7. Right click on Users and select New User…
8. In the Database User – New dialog, under General page, enter in User name
9. In front of Login name, click on the browse (…) button. You will see a Select Login dialog
10. Click on Browse button and check the Login you created above and click OK. Close the Select Login dialog by click on OK
11. Next under Database User – New dialog, click on Securables page. Click on Add button. This will open up Add Objects dialog.
12. Select Specific objects and click OK. This will open up Select Objects dialog.
13. Click on Object Types button. This will open up Select Object Types dialog.
14. Check the desired object type (Tables, Views, Stored Procedures etc) which Login will have access to. Click OK
15. Under Select Objects dialog, click on Browse button. This will open up Browse for Objects dialog. Select the desired objects which Login will have access to. Click OK.
16. Click on OK to close Select Objects dialog.
17. Under Database User - New, you can select each object in Securables list and specify permission level on each object in the Explicit permissions for list
18. Click on OK to close the Database User - New dialog. You have now set permissions on the specific user.
I hope you have found this post to be useful. Please do provide your feedback and stay tuned for more…
Saturday, June 19, 2010
Understanding HTML, XHTML and DHTML
As programmers, we come across the terms HTML, XHTML and DHTML on a daily basis. The difference between these is subtle but important to understand. This post will elaborate these concepts in further details. I would suggest reading my other post HTML Document Structure before proceeding.
HTML
Hyper Text Markup Language or HTML is a markup language used for creating web documents. It has the following characteristics:
1. HTML is a markup language and not a programming language.
2. HTML is an application of SGML (Standard Generalized Markup Language). SGML is a system for defining markup languages.
3. HTML markup consists of elements where each element has a start and end tag. The content of the element is contained between the two tags.
4. HTML also includes character reference and symbols such as ‘<’ is used to represent the ‘<’ sign.
5. An HTML document allows comments.
6. HTML documents are validated by Document Type Definition or DTD.
XHTML
Extensible Hyper Text Markup Language or XHTML is the reevaluation of HTML 4. Both have sharp resembles but with subtle differences. However, the most critical difference between the two is that XHTML is an application of XML . This means that XHTML follows the XML syntax rules for validating web documents. These rules include the following:
1. XHTML is case-sensitive.
2. The entire document has only one root element.
3. Elements must be nested in the correct order.
4. Every element must have a closing tag leading to a well-formed document. Elements without content such ‘br’ must have a self-closing tag.
5. The element tags and attributes are in lowercase.
6. Attributes must be in double or single quotes.
7. Each attribute must have a corresponding value. There is no notion of default values.
8. If there is a syntax error in the XHTML document, the entire document is aborted from loading.
9. Comments are limited in XHTML.
10. The id attribute is used instead of name attribute.
Since XHTML complies with the above rules, it is portable across different platforms including web browsers, mobile phones, palm devices or any reduced browser. HTML, on the other hand, can ignore these rules altogether leading to document with syntax errors.
XHTML also deals with CSS differently. This includes the following characteristics:
1. Element Selectors are case sensitive.
2. In HTML certain properties (background, overflow) of the BODY element applies to the root HTML element as well. This is not true for XHTML.
3. In HTML, even if we omit some tags, elements still exist in the DOM and hence the CSS properties apply to them. This is not true for XHTML. The CSS will only apply to elements with proper markup.
4. MIME types (Content-Type header specified in HTML/XHTML document) are very important when using style-sheets in XHTML document. An XHTML document can work with application/xhtml+xml, application/xml and text/xml MIME types. An XHMTL document using text/xml MIME type is parsed as HTML. However, a style sheet written specifically for XHTML document may not work with text/xml MIME type (since its interpreted as HTML).
XHTML also deals with JavaScript differently. Some of these characteristics include the following:
1. XHTML does not support the .innerHTML property.
2. XHTML does not support document.write () otherwise it confuses the browser which is unable to tell whether a document is well formed or not. For example suppose we have a tag </MyTag> somewhere in the document. Obviously this is not a well formed tag. However, if somewhere above JavaScript uses the statement ‘document.write (“<MyTag>”);’ it will make it a valid tag. This means that unless the document is fully served, the browser cannot if it is a well formed document.
3. DOM methods are replaced by respective namespace-based methods.
DHTML
Unlike HTML and XHTML, Dynamic HTML or DHTML is not an industry standard and is not supported by W3C, IEEE or ISO. The term DHTM was coined by Microsoft. DHTML represents a set of several technologies/standards including HTML/XHTML, DOM, CSS and JavaScript. The merger of these technologies leads to development of Rich Client Applications. HTML/XHTML and CSS are used to create the static but rich visual appearance while JavaScript and DOM are used to make the web applications dynamic.
With this we come to the end of this post. I hope this post has given you a good idea about the difference between HTML, XHTML and DHTML. Do provide your feedback and stay tuned for more…
HTML
Hyper Text Markup Language or HTML is a markup language used for creating web documents. It has the following characteristics:
1. HTML is a markup language and not a programming language.
2. HTML is an application of SGML (Standard Generalized Markup Language). SGML is a system for defining markup languages.
3. HTML markup consists of elements where each element has a start and end tag. The content of the element is contained between the two tags.
4. HTML also includes character reference and symbols such as ‘<’ is used to represent the ‘<’ sign.
5. An HTML document allows comments.
6. HTML documents are validated by Document Type Definition or DTD.
XHTML
Extensible Hyper Text Markup Language or XHTML is the reevaluation of HTML 4. Both have sharp resembles but with subtle differences. However, the most critical difference between the two is that XHTML is an application of XML . This means that XHTML follows the XML syntax rules for validating web documents. These rules include the following:
1. XHTML is case-sensitive.
2. The entire document has only one root element.
3. Elements must be nested in the correct order.
4. Every element must have a closing tag leading to a well-formed document. Elements without content such ‘br’ must have a self-closing tag.
5. The element tags and attributes are in lowercase.
6. Attributes must be in double or single quotes.
7. Each attribute must have a corresponding value. There is no notion of default values.
8. If there is a syntax error in the XHTML document, the entire document is aborted from loading.
9. Comments are limited in XHTML.
10. The id attribute is used instead of name attribute.
Since XHTML complies with the above rules, it is portable across different platforms including web browsers, mobile phones, palm devices or any reduced browser. HTML, on the other hand, can ignore these rules altogether leading to document with syntax errors.
XHTML also deals with CSS differently. This includes the following characteristics:
1. Element Selectors are case sensitive.
2. In HTML certain properties (background, overflow) of the BODY element applies to the root HTML element as well. This is not true for XHTML.
3. In HTML, even if we omit some tags, elements still exist in the DOM and hence the CSS properties apply to them. This is not true for XHTML. The CSS will only apply to elements with proper markup.
4. MIME types (Content-Type header specified in HTML/XHTML document) are very important when using style-sheets in XHTML document. An XHTML document can work with application/xhtml+xml, application/xml and text/xml MIME types. An XHMTL document using text/xml MIME type is parsed as HTML. However, a style sheet written specifically for XHTML document may not work with text/xml MIME type (since its interpreted as HTML).
XHTML also deals with JavaScript differently. Some of these characteristics include the following:
1. XHTML does not support the .innerHTML property.
2. XHTML does not support document.write () otherwise it confuses the browser which is unable to tell whether a document is well formed or not. For example suppose we have a tag </MyTag> somewhere in the document. Obviously this is not a well formed tag. However, if somewhere above JavaScript uses the statement ‘document.write (“<MyTag>”);’ it will make it a valid tag. This means that unless the document is fully served, the browser cannot if it is a well formed document.
3. DOM methods are replaced by respective namespace-based methods.
DHTML
Unlike HTML and XHTML, Dynamic HTML or DHTML is not an industry standard and is not supported by W3C, IEEE or ISO. The term DHTM was coined by Microsoft. DHTML represents a set of several technologies/standards including HTML/XHTML, DOM, CSS and JavaScript. The merger of these technologies leads to development of Rich Client Applications. HTML/XHTML and CSS are used to create the static but rich visual appearance while JavaScript and DOM are used to make the web applications dynamic.
With this we come to the end of this post. I hope this post has given you a good idea about the difference between HTML, XHTML and DHTML. Do provide your feedback and stay tuned for more…
Thursday, June 17, 2010
HTML Document Structure
In this post, I will talk about HTML Document Structure. This post is not a tutorial on HTML for which you can find many useful links online. This post will give you an overview of what a typical HTML Document looks like. So let us dive in straight.
What is HTML
Hyper Text Markup Language or HTML is a markup language (and not a programming language) used for creating web pages. One may ask what a markup language is. Well a markup language uses tags to create different parts of a document. To better understand this, you must notice when a person reviews a document and marks (underline, highlight) any spelling, grammatical or technical mistakes. At the end of the review, the document will probably have several markups. The same concept applies to a markup language where different tags create the contents of a webpage.
A HTML document contains different parts known as elements. For example, to make some text bold, we use the <b></b> element. Each element can be divided into three parts; Start Tag, Content and End Tag. A tag is a ‘markup’ which is delimited by < and >. The End tag has an additional ‘/’ after <. In the above example, the start tag is <b> and the end tag is </b>. The contents of the element are surrounded by the start and end tags. Some elements (such as new-line break </br>) do not need a closing tag as they have no Content.
Each element can also have attributes. An attribute represents a property of the element. For example, an input element has a type attribute where the type may specify it as button or text box. Attribute values must be delimited in single or double quotes. Attributes are only included in the start tag and are case-insensitive. However, their values can be case-sensitive.
The following listing shows what a typical HTML document looks like:
Listing 1
Now let us explore the above document in greater detail.
!DOCTYPE Declaration
Each HTML Document begins with Document Type Declaration or DOCTYPE. This is a standard defined under HTML rules. The !DOCTYPE defines the version of HTML used by the HTML document. This information is used by web browsers to validate the document’s syntax.
The DOCTYPE instructs the browser to associate a particular Document Type Definition or DTD - which defines set of rules for a markup language – with an HTML document. Typically, a browser consists of a layout engine which performs “switching” to switch over to the particular DTD defined in the DOCTYPE definition. This way, the browser knows precisely which DTD Rules to apply to render the HTML Web Page correctly. Following are the different DOCTYPE definitions supported by HTML 4.01:
HTML 4.01 Strict : This DTD includes standard HTML elements and attributes but does not include presentational elements such as fonts. This DTD does not allow Framesets. The definition takes the following form:
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
HTML 4.01 Transitional : This DTD includes standard HTML elements and attributes in addition to presentation elements including fonts. Frameset is not allowed. The definition takes the following form:
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
HTML 4.01 Frameset : This DTD is the same as HTML 4.01 Transitional in addition to Frameset support. The definition takes the following form:
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Frameset//EN" "http://www.w3.org/TR/html4/frameset.dtd">
The above are the standard DTD types supported by HTML 4.01. With the release of XTHML (HTML which conforms to XML standards - more on this in my following post), the following additional DTD types have been introduced:
XHTML 1.0 Strict: Similar to its HTML 4.01 Strict counterpart with support for XHTML. The definition is of the following form:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
XHTML 1.0 Transitional : Similar to its HTML 4.01 Transitional counterpart with support for XHTML. The definition takes the following form:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
XHTML 1.0 Frameset : Again similar to its HTML 4.01 Frameset counterpart with support for XHTML. The definition takes the following form:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Frameset//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-frameset.dtd">
XHTML 1.1: Similar to its XHTML 1.0 Strict in addition to allowing adding modules. The definition takes the following form:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
HTML Element
The HTML element is the root element and acts as the parent container for the rest of the elements. The rest of the elements are contained within the start and end tag or the HTML element as shown in Listing 1. The two child elements of the HTML element are discussed in the following paragraphs.
HEAD Element
The HEAD element holds set of different tags which provide page related information. This section is the first part to be loaded in the browser. The HEAD section contains the following elements:
Title : Provides a brief description of the webpage such as ‘HTML Tutorial’ or ‘Welcome to my homepage’
STYLE : This element defines the stylesheet for a webpage. A stylesheet defines the visual layout of a webpage including colors, margins, background etc.
META : META element allows defining information about the document. It is like information about information. It does not describe the contents of he webpage. For example, this information can include the author of the page, page language, date-created etc. This information is in the form of name/value pairs and is also used by Search Engines while indexing the webpage.
SCRIPT :This element allows defining scripts such as JavaScript, VB Script for the webpage.
Amongst the above, only the TITLE element is a visual. The rest are non-visual elements used for information keeping. As mentioned above, the HEAD sections loads first in the browser that’s why you can see the title even before the page is rendered.
BODY Element
The BODY element defines the contents of a webpage. The contents of the webpage may include headings, tables, paragraphs, images, hyperlinks etc. The body may be implemented using the BODY or the FRAMESET element. Framesets are used to divide the webpage into different portions.
What is HTML
Hyper Text Markup Language or HTML is a markup language (and not a programming language) used for creating web pages. One may ask what a markup language is. Well a markup language uses tags to create different parts of a document. To better understand this, you must notice when a person reviews a document and marks (underline, highlight) any spelling, grammatical or technical mistakes. At the end of the review, the document will probably have several markups. The same concept applies to a markup language where different tags create the contents of a webpage.
A HTML document contains different parts known as elements. For example, to make some text bold, we use the <b></b> element. Each element can be divided into three parts; Start Tag, Content and End Tag. A tag is a ‘markup’ which is delimited by < and >. The End tag has an additional ‘/’ after <. In the above example, the start tag is <b> and the end tag is </b>. The contents of the element are surrounded by the start and end tags. Some elements (such as new-line break </br>) do not need a closing tag as they have no Content.
Each element can also have attributes. An attribute represents a property of the element. For example, an input element has a type attribute where the type may specify it as button or text box. Attribute values must be delimited in single or double quotes. Attributes are only included in the start tag and are case-insensitive. However, their values can be case-sensitive.
The following listing shows what a typical HTML document looks like:
Listing 1
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
<title>Untitled Page</title>
</head>
<body>
<h1>HTML Document</h1>
<p>This post talks about a HTML Document</p>
</body>
</html>
Now let us explore the above document in greater detail.
!DOCTYPE Declaration
Each HTML Document begins with Document Type Declaration or DOCTYPE. This is a standard defined under HTML rules. The !DOCTYPE defines the version of HTML used by the HTML document. This information is used by web browsers to validate the document’s syntax.
The DOCTYPE instructs the browser to associate a particular Document Type Definition or DTD - which defines set of rules for a markup language – with an HTML document. Typically, a browser consists of a layout engine which performs “switching” to switch over to the particular DTD defined in the DOCTYPE definition. This way, the browser knows precisely which DTD Rules to apply to render the HTML Web Page correctly. Following are the different DOCTYPE definitions supported by HTML 4.01:
HTML 4.01 Strict : This DTD includes standard HTML elements and attributes but does not include presentational elements such as fonts. This DTD does not allow Framesets. The definition takes the following form:
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
HTML 4.01 Transitional : This DTD includes standard HTML elements and attributes in addition to presentation elements including fonts. Frameset is not allowed. The definition takes the following form:
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
HTML 4.01 Frameset : This DTD is the same as HTML 4.01 Transitional in addition to Frameset support. The definition takes the following form:
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Frameset//EN" "http://www.w3.org/TR/html4/frameset.dtd">
The above are the standard DTD types supported by HTML 4.01. With the release of XTHML (HTML which conforms to XML standards - more on this in my following post), the following additional DTD types have been introduced:
XHTML 1.0 Strict: Similar to its HTML 4.01 Strict counterpart with support for XHTML. The definition is of the following form:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
XHTML 1.0 Transitional : Similar to its HTML 4.01 Transitional counterpart with support for XHTML. The definition takes the following form:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
XHTML 1.0 Frameset : Again similar to its HTML 4.01 Frameset counterpart with support for XHTML. The definition takes the following form:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Frameset//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-frameset.dtd">
XHTML 1.1: Similar to its XHTML 1.0 Strict in addition to allowing adding modules. The definition takes the following form:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
HTML Element
The HTML element is the root element and acts as the parent container for the rest of the elements. The rest of the elements are contained within the start and end tag or the HTML element as shown in Listing 1. The two child elements of the HTML element are discussed in the following paragraphs.
HEAD Element
The HEAD element holds set of different tags which provide page related information. This section is the first part to be loaded in the browser. The HEAD section contains the following elements:
Title : Provides a brief description of the webpage such as ‘HTML Tutorial’ or ‘Welcome to my homepage’
STYLE : This element defines the stylesheet for a webpage. A stylesheet defines the visual layout of a webpage including colors, margins, background etc.
META : META element allows defining information about the document. It is like information about information. It does not describe the contents of he webpage. For example, this information can include the author of the page, page language, date-created etc. This information is in the form of name/value pairs and is also used by Search Engines while indexing the webpage.
SCRIPT :This element allows defining scripts such as JavaScript, VB Script for the webpage.
Amongst the above, only the TITLE element is a visual. The rest are non-visual elements used for information keeping. As mentioned above, the HEAD sections loads first in the browser that’s why you can see the title even before the page is rendered.
BODY Element
The BODY element defines the contents of a webpage. The contents of the webpage may include headings, tables, paragraphs, images, hyperlinks etc. The body may be implemented using the BODY or the FRAMESET element. Framesets are used to divide the webpage into different portions.
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