barcode generator in vb.net code project Using Predicates in Software

Maker Code 39 Extended in Software Using Predicates

Using Predicates
ANSI/AIM Code 39 Recognizer In None
Using Barcode Control SDK for Software Control to generate, create, read, scan barcode image in Software applications.
Generate Code 39 Extended In None
Using Barcode printer for Software Control to generate, create ANSI/AIM Code 39 image in Software applications.
Using the BETWEEN Predicate
Decode Code39 In None
Using Barcode decoder for Software Control to read, scan read, scan image in Software applications.
Generating Code 39 Extended In Visual C#.NET
Using Barcode creation for Visual Studio .NET Control to generate, create Code39 image in .NET framework applications.
Strictly speaking, the BETWEEN predicate is not a comparison predicate, at least not as it is presented in the SQL:2006 standard. It is, however, so similar in function to a combination of the greater than or equal to operator and the less than or equal to operator that it s worth discussing here. The BETWEEN predicate is used in conjunction with the AND keyword to identify a range of values that can be included as a search condition in the WHERE clause. Values in the identified column must fall within that range in order to evaluate to true. When you use the BETWEEN clause, you must specify the applicable column, the low end of the range, and the high end of the range. The following example (which is based on the CDS_ON_HAND table in Figure 9-1) specifies a range from 14 through 16:
Code 39 Full ASCII Drawer In VS .NET
Using Barcode encoder for ASP.NET Control to generate, create Code 39 Full ASCII image in ASP.NET applications.
Drawing Code 39 In .NET Framework
Using Barcode encoder for Visual Studio .NET Control to generate, create ANSI/AIM Code 39 image in Visual Studio .NET applications.
SELECT CD_TITLE, RETAIL_PRICE FROM CDS_ON_HAND WHERE RETAIL_PRICE BETWEEN 14 AND 16;
Making Code 39 Full ASCII In VB.NET
Using Barcode drawer for VS .NET Control to generate, create Code 39 image in .NET framework applications.
Data Matrix 2d Barcode Generator In None
Using Barcode creator for Software Control to generate, create Data Matrix ECC200 image in Software applications.
The RETAIL_PRICE value for each selected row must fall within that range, including the end points. If you execute this statement, only four rows are included in the query results:
Code 39 Creation In None
Using Barcode creator for Software Control to generate, create Code 3/9 image in Software applications.
Create UCC-128 In None
Using Barcode encoder for Software Control to generate, create USS-128 image in Software applications.
CD_TITLE --------------Blue Court and Spark Past Light Kojiki RETAIL_PRICE -----------14.99 14.99 15.99 15.99
Draw Bar Code In None
Using Barcode generation for Software Control to generate, create bar code image in Software applications.
Bar Code Generation In None
Using Barcode drawer for Software Control to generate, create barcode image in Software applications.
Now let s take a look at a query similar to the one in the last example, only this time using comparison predicates rather than the BETWEEN predicate:
Code11 Creator In None
Using Barcode encoder for Software Control to generate, create USD - 8 image in Software applications.
Create Bar Code In None
Using Barcode printer for Office Excel Control to generate, create barcode image in Office Excel applications.
SELECT FROM WHERE AND CD_TITLE, RETAIL_PRICE CDS_ON_HAND RETAIL_PRICE >= 14 RETAIL_PRICE <= 16;
Bar Code Generator In None
Using Barcode printer for Office Excel Control to generate, create bar code image in Microsoft Excel applications.
Draw UPC Symbol In Visual C#.NET
Using Barcode generator for VS .NET Control to generate, create UPC Symbol image in Visual Studio .NET applications.
Notice that two predicates are used: one with the greater than or equal to operator and one with the less than or equal to operator. This SELECT statement will produce the same query results as the previous SELECT statement. Now let s return to the BETWEEN predicate. As with any predicate, you can combine the BETWEEN predicate with other predicates. In the following statement, the WHERE clause includes a BETWEEN predicate and a comparison predicate:
Bar Code Decoder In Visual Studio .NET
Using Barcode reader for .NET Control to read, scan read, scan image in .NET framework applications.
Encode Code-39 In VB.NET
Using Barcode generator for Visual Studio .NET Control to generate, create Code39 image in VS .NET applications.
SELECT FROM WHERE AND CD_TITLE, RETAIL_PRICE CDS_ON_HAND RETAIL_PRICE BETWEEN 14 AND 16 INVENTORY > 10;
Code 128 Code Set C Recognizer In Visual C#
Using Barcode scanner for Visual Studio .NET Control to read, scan read, scan image in Visual Studio .NET applications.
Print Data Matrix In Visual Basic .NET
Using Barcode generator for Visual Studio .NET Control to generate, create Data Matrix image in .NET applications.
SQL: A Beginner s Guide
As a result of both predicates, the query results can include only those rows with a RETAIL_ PRICE value that falls within the range of 14 through 16 and with an INVENTORY value greater than 10. When you execute this query, only two rows are returned:
CD_TITLE --------------Blue Court and Spark RETAIL_PRICE -----------14.99 14.99
Again, you will notice that the query results don t include the INVENTORY column even though that column is specified in a predicate in the WHERE clause. You ll also notice that more than one column is referenced in the WHERE clause. In addition to what you ve seen so far with the BETWEEN predicate, you can also use the clause to specify the inverse of a condition. This is done by using the NOT keyword within the predicate. For example, suppose you change the last example to the following:
SELECT CD_TITLE, RETAIL_PRICE FROM CDS_ON_HAND WHERE RETAIL_PRICE NOT BETWEEN 14 AND 16;
The rows returned in the query result will include all rows that do not have a RETAIL_PRICE value within the range of 14 through 16. When you execute the statement, three rows are returned:
CD_TITLE ----------------------------Famous Blue Raincoat That Christmas Feeling Patsy Cline: 12 Greatest Hits RETAIL_PRICE -----------16.99 10.99 16.99
Notice that all values within the specified range have been excluded from the query results. If you find the NOT keyword confusing (as many people do), you can write an equivalent WHERE clause using the OR keyword and the greater than and less than operators as follows:
WHERE RETAIL_PRICE < 14 OR RETAIL_PRICE > 16;
Return Null Values
As you might recall from 4, a null value is used in place of a value when that value is undefined or not known. A null indicates that the value is absent. This is not the same as a zero, a blank, or a default value. By default, SQL allows nulls to be used in place of regular values (although you can override the default by including a NOT NULL constraint in your column definition). In those cases where null values are permitted, you might find it necessary to specify that null values be returned when you query a table. For this reason, SQL provides the NULL predicate, which allows you to define search conditions that return null values.
9:
Copyright © OnBarcode.com . All rights reserved.