The Object Explorer displays a list of items as a tree-style. One of the most regularly used items will be the name of the server you are using. If you are just starting to learn database development or you are a junior database developer, you may use or see only one server. In some cases, you may be dealing with many servers. Regardless, you should always know what server you are currently connecting to. This is easy to check  with the first node of the Object Explorer. In the following example, the server is named Central:

The name of the server is followed by parentheses.

In the previous section, we saw that, to establish a connection to a server, you must authenticate yourself. In some cases you may use the same account over and over again. In some other cases you may have different accounts that you use for different scenarios, such as one account for database development, one account for database management, and/or one account for database testing. When many connections have been made, each connection is represented in the Object Explorer by its own node and each connection has its own objects (sub-nodes):

As mentioned previously, to close a connection, you can right-click it and click Disconnect:

Some operations cannot be performed by some accounts. When performing some operations, you should always know what account you are using. You can check this in the parentheses of the server name. In the following connection, an account called Administrator is currently logged in to a server named Central:

1. In the Object Explorer, right-click ComputerName (SQL Server ... - operez) and click Disconnect
2. Right-click ComputerName (SQL Server ... - rkouma) and click Disconnect
3. Close Microsoft SQL Server
4. Start it again
5. Select Windows Authentication
6. Click Connect

We saw that, by default, the right area of Microsoft SQL Server Management Studio displays an empty gray window. When you select something in the Object Explorer, you can use that right area to display more detailed information about the select item. To do this, on the main menu, you can click View -> Object Explorer Details. The main are on the right side would then be filled with information:

Probably the most regular node you will be interested in, is labeled Databases. This node holds the names of databases on the server you are connected to. Also, from that node, you can perform almost any necessary operation of a database. To see most of the regularly available actions, you can expand the Databases node and some of its children. You can then right-click either Databases or one of its child nodes. For example, to start PowerShell, you can right-click  the Databases node or the server name and click PowerShell:

When the PowerShell comes up, what it displays depends on what you had right-clicked.

Although you will perform many of your database operations visually, some other operations will require that you write code. To assist with with this, Microsoft SQL Server provides a code editor and various code templates.

To open the editor:

• On the main menu, you can click File -> New -> Query With Current Connection
• On the Standard toolbar, click the New Query button
• In the Object Explorer, right-click the name of the server and click New Query

This would create a new window and position it on the right side of the interface. Whether you have already written code or not, you can save the document of the code editor at any time. To save it:

• You can press Ctrl + S
• On the main menu, you can click File -> Save SQLQueryX.sql...
• On the Standard toolbar, you can click the Save button

You will be required to provide a name for the file. After saving the file, its name would appear on the tab of the document.

After establishing a connection, you can take actions, such as creating a database and/or manipulating data. To provide the ability to create and manipulate a database, you use data manipulation language (DML). There are many of them on the market. The Structured Query Language, known as SQL, is a DML used on various computer systems to create and manage databases.

SQL can be pronounced Sequel or S. Q. L. In our lessons, we will consider the Sequel pronunciation. For this reason, the abbreviation will always be considered as a word, which would result in “A SQL statement” instead of "An SQL statement". Also, we will regularly write, “The SQL” instead of “The SQL language, as the L already represents Language.

Like other non-platform specific languages such as C/C++, Pascal, or Java, the SQL you learn can be applied to various database systems. To adapt the SQL to Microsoft SQL Server, the company developed Transact-SQL as Microsoft's implementation of SQL. Transact-SQL is the language used internally by Microsoft SQL Server and MSDE. Although SQL Server highly adheres to the SQL standards, it has some internal details that may not be applied to other database systems like MySQL, Oracle, or even Microsoft Access, etc; although they too fairly conform to the standard.

The SQL we will learn and use here is Transact-SQL. In other words, we will assume that you are using Microsoft SQL Server as your platform for learning about databases. This means that, unless specified otherwise, most of the time, on this site, the word SQL refers to Transact-SQL or the way the language is implemented in Microsoft SQL Server.

As a computer language, the SQL is used to give instructions to an internal program called an interpreter. As we will learn in various sections, you must make sure you give precise instructions. SQL is not case-sensitive. This means that CREATE, create, and Create mean the same thing. It is a tradition to write SQL's own words in uppercase. This helps to distinguish SQL instructions with the words you use for your database.

As we will learn in this and the other remaining lessons of this site, you use SQL by writing statements. To help you with this, Microsoft SQL Server provides a window, also referred to as the Query Window, that you can use to write your SQL code. To access it, on the left side of the window, you can right-click the name of the server and click New Query. In the same way, you can open as many instances as the New Query as you want.

When the Query window comes up, it display a blank child window in which you can write your code. The code you write is a document and it can be saved as a file. The file would have the extension .sql. Every time you open a new query, it is represented with a tab. To switch from one code part to another, you can click its tab. To dismiss an instance of the query, first access it (by clicking its tab), then, on the right side, click the close button . If you had written code in the query window, when you close it, you would be asked to save your code. If you want to preserve your code, then save it. If you had already executed the code in the window (we will learn how to write and execute SQL code), you don't have to save the contents of the window.

In the next sections and lessons, we will learn various techniques of creating SQL statements with code. By default, when a new query window appears, it is made of a wide white area where you write your statements:

After writing a statement, you can execute it, either to make it active or simply to test it. To execute a statement:

• You can press F5
• On the main menu, you can click Query -> Execute
• On the SQL Editor toolbar, you can click the Execute button
• You can right-click somewhere in the code editor and click Execute

When you execute code, code editor becomes divided into two horizontal sections:

Also, when you execute code, the interpreter would first analyze it. If there is an error, it would display one or more red lines of text in its bottom section. Here is an example:

If there is no error in the code, what happens when you execute a statement depends on the code and the type of statement.

A comment is text that the SQL interpreter would not consider as code. As such, a comment is written any way you like. What ever it is made of would not be read. Transact-SQL supports two types of comments. The style of comment that starts with /* and ends with */ can be used. To apply it, start a line with /*, include any kind of text you like, on as many lines as you want. To close the commented section, type */. Here is an example of a line of comment:

/* First find out if the database we want to create exists already */

A comment can also be spread on more than one line, like a paragraph. Here is an example:

/* First find out if the MotorVehicleDivision database we 
   want to create exists already.
   If that database exists, we don't want it anymore. So,
   delete it from the system. */

Transact-SQL also supports the double-dash comment. This comment applies to only one line of text. To use it, start the line with --. Anything on the right side of -- is part of a comment and would not be considered as code. Here is an example:

-- =============================================
-- Database: MotorVehicleDivision
-- =============================================

/* First find out if the MotorVehicleDivision database we 
   want to create exists already.
   If that database exists, we don't want it anymore. So,
   delete it from the system. */


-- Now that the database is not in the system, create it

In SQL, after writing a statement, you can end it with a semi-colon. In fact, if you plan to use many statements in one block, you should end each with a semi-colon. When many statements are used, some of them must come after others.

To separate statements, that is, to indicate when a statement ends, you can use the GO keyword (in reality and based on SQL standards, it is the semi-colon that would be required, but the Microsoft SQL Server interpreter accepts GO as the end of a statement).