note in Visual C#

Encoder QR-Code in Visual C# note

When looking through SQL Server Books Online and other Transact-SQL (T-SQL) syntax help, you frequently see the term expression. In SQL Server Books Online, an expression is defined as a combination of symbols and operators that evaluate to a single data value.

In the Person table, the PersonType column contains EM for employees. Figure 1-4 shows a command that builds off the command shown previously and adds a column spelling out Employee in a column titled Description for each row. The query also restricts the result set to rows containing a PersonType of EM .

In this practice session, you retrieve data from the ProductSubcategory table. You use the WHERE clause, the LIKE operator, and the ORDER BY clause to manipulate the result set.

In this exercise, you write a basic SELECT statement that retrieves all rows and columns from the ProductSubcategory table. You then modify the statement to modify the result set returned.

1. 2.

If necessary, start SSMS, connect to your SQL Server instance, and open a new query window. In the existing query window, type and execute the following code to specify the AdventureWorks2008 database, and then return all rows and all columns in the ProductSubcategory table:

USE AdventureWorks2008;

SELECT * FROM Production.ProductSubcategory;

In the existing query window, below the existing code, type, highlight, and execute the following code to return only the ProductSubcategoryID, ProductCategoryID, Name, and ModifiedDate columns:

SELECT ProductSubcategoryID, ProductCategoryID , Name, ModifiedDate FROM Production.ProductSubcategory;

In the existing query window, below the existing code, type, highlight, and execute the following code to return rows where the word bike is found somewhere in the Name column:

SELECT ProductSubcategoryID, ProductCategoryID , Name, ModifiedDate FROM Production.ProductSubcategory WHERE Name LIKE '%Bike%';

In the existing query window, below the existing code, type, highlight, and execute the following code to add a column alias to the Name column to clarify it as the subcategory name. Notice the change to the column title in the result set:

SELECT ProductSubcategoryID, ProductCategoryID , Name AS 'Subcategory Name', ModifiedDate FROM Production.ProductSubcategory WHERE Name LIKE '%Bike%';

In the existing query window, below the existing code, type, highlight, and execute the following code to sort the result set by the subcategory name:

SELECT ProductSubcategoryID, ProductCategoryID , Name AS 'Subcategory Name', ModifiedDate FROM Production.ProductSubcategory WHERE Name LIKE '%Bike%' ORDER BY [Subcategory Name];

7. 8.

The SELECT statement can be used to retrieve data from a table or view. The SELECT statement result set can be filtered by adding a WHERE clause. The SELECT statement result set can be sorted by using the ORDER BY clause. Concatenation, aliases, and string literals can be used to manipulate and format the result set.

With normalized databases, information required for a single result set may be located in two or more tables within the database.

After this lesson, you will be able to:

Write queries that use the INNER, OUTER, FULL, and CROSS JOIN operators. Explain the difference between the different JOIN operators.

The JOIN operator allows you to return data from columns stored in multiple related tables. Although actual relationships, implemented by creating PRIMARY KEY and FOREIGN KEY constraints, are not required, there does need to be at least one column in each of the tables that has the same meaning for the results to be meaningful. If a column with the same column name exists in more than one table in the query, you must qualify the column with the table name when defining the select list or listing columns in the WHERE clause or other clauses within the SELECT statement. For example, the Name column exists in the Production.Product, Production.Subcategory, and Production.Category tables. If you write a query joining these tables and you want to include the Name columns in the select list or elsewhere in the query, you need to qualify them as Production.Product .Name, and so on. You can use table aliases to avoid lengthy code caused by long schema and object names. The following example shows the use of aliases:

SELECT FirstName, LastName, JobTitle, VacationHours, SickLeaveHours FROM HumanResources.Employee E INNER JOIN Person.Person P ON E.BusinessEntityID = P.BusinessEntityID;

When defining a JOIN condition, you need to define the tables to be joined, the join type, and a join condition, which is made up of the columns on which the tables are joined and the logical operator. INNER JOIN is the default join type when only the keyword JOIN is specified.