PostgreSQL 8 for Windows in .NET framework

Printer EAN13 in .NET framework PostgreSQL 8 for Windows

PostgreSQL 8 for Windows
Recognizing European Article Number 13 In Visual Studio .NET
Using Barcode Control SDK for Visual Studio .NET Control to generate, create, read, scan barcode image in Visual Studio .NET applications.
EAN / UCC - 13 Encoder In Visual Studio .NET
Using Barcode creator for .NET framework Control to generate, create EAN 13 image in .NET applications.
Similar to the UPDATE command, you can also specify columns in other tables in the WHERE clause Before doing that you must precede the WHERE clause with the USING option, specifying a list of tables the columns come from (Note that since the DELETE command already uses the FROM keyword, it uses the USING keyword to specify the tables This is different from the UPDATE command)
EAN-13 Supplement 5 Recognizer In .NET
Using Barcode decoder for Visual Studio .NET Control to read, scan read, scan image in VS .NET applications.
Barcode Printer In VS .NET
Using Barcode maker for VS .NET Control to generate, create bar code image in .NET framework applications.
QUERYING DATA
Scanning Barcode In VS .NET
Using Barcode decoder for .NET Control to read, scan read, scan image in Visual Studio .NET applications.
EAN-13 Supplement 5 Maker In Visual C#.NET
Using Barcode printer for VS .NET Control to generate, create EAN-13 image in Visual Studio .NET applications.
Quite possibly the most important function you will perform in your applications is to query existing data in the database While many application developers spend a great deal of time concentrating on fancy GUI front ends to their applications, the real heart of the application is the behind-the-scenes SQL used to query data in the database If this code is inefficient, it can cause huge performance problems and make an application virtually useless for customers As a database application programmer, it is essential that you understand how to write good SQL queries The SQL command used for queries is SELECT Because of its importance, much work has been done on the format of the SELECT command, to make it as versatile as possible Unfortunately, with versatility comes complexity Because of the complexity of the SELECT command, the command format has become somewhat unwieldy and intimidating for the beginner To try and keep things simple, the next few sections demonstrate how to use some of the more basic features of the SELECT command Some more advanced features of the SELECT command format will be presented in 7, after you have had a chance to get somewhat familiar with it here
EAN-13 Printer In VS .NET
Using Barcode maker for ASP.NET Control to generate, create EAN13 image in ASP.NET applications.
Draw EAN-13 Supplement 5 In Visual Basic .NET
Using Barcode encoder for .NET Control to generate, create EAN / UCC - 13 image in Visual Studio .NET applications.
The Basic Query Format
Painting Code 128 In Visual Studio .NET
Using Barcode creator for .NET Control to generate, create Code128 image in Visual Studio .NET applications.
GS1 DataBar Creator In VS .NET
Using Barcode printer for VS .NET Control to generate, create GS1 DataBar Truncated image in .NET framework applications.
The SQL SELECT command is used to query data from tables in the database The basic format of the SELECT command is
Making EAN / UCC - 14 In VS .NET
Using Barcode generator for Visual Studio .NET Control to generate, create USS-128 image in VS .NET applications.
Generate USS 93 In .NET
Using Barcode drawer for .NET Control to generate, create Code 93 Full ASCII image in .NET applications.
SELECT columnlist from table
Make Code 128A In None
Using Barcode generator for Software Control to generate, create Code 128C image in Software applications.
Drawing UPC Symbol In Java
Using Barcode creator for Java Control to generate, create UPC Code image in Java applications.
The columnlist parameter specifies the columns from the table you want displayed in the output It can be a comma-separated list of column names in the table, or the wildcard character (the asterisk) to specify all columns, as was shown in the SELECT examples used earlier in this chapter:
UPC A Drawer In None
Using Barcode creation for Software Control to generate, create UPC A image in Software applications.
Painting Code128 In Java
Using Barcode drawer for Java Control to generate, create Code 128 Code Set B image in Java applications.
SELECT * FROM store"Customer";
Painting Barcode In None
Using Barcode drawer for Office Excel Control to generate, create barcode image in Office Excel applications.
Code 3 Of 9 Recognizer In Visual Studio .NET
Using Barcode scanner for .NET Control to read, scan read, scan image in .NET framework applications.
Sorting Output Data
Generating Data Matrix ECC200 In Java
Using Barcode generation for Android Control to generate, create Data Matrix 2d barcode image in Android applications.
EAN13 Recognizer In Visual C#
Using Barcode scanner for .NET Control to read, scan read, scan image in .NET applications.
The output of the SELECT command is called a result set The result set contains only the data columns specified in the SELECT command The result set is only temporary, and by default is not stored in any tables
6:
Using Basic SQL
By default, the records are not displayed in any particular order As records are added and removed from the table, PostgreSQL may place new records anywhere within the table Even if you enter data in a particular order using INSERT commands, there is still no guarantee that the records will display in the same order as a result of a query If you need to specify the order of the displayed records, you must use the ORDER BY clause:
test=> select "CustomerID", "LastName", "FirstName" from store"Customer" test-> order by "FirstName"; CustomerID | LastName | FirstName + + BLU002 | Blum | Barbara BLU004 | Blum | Jessica BLU003 | Blum | Katie BLU001 | Blum | Rich (4 rows) test=>
In this example (taken from the test database used in 5), only the columns specified in the SELECT command are displayed, ordered by the FirstName column The default order used by the SELECT command is ascending order, based on the data type of the column you selected to order by You can change the order to descending by using the DESC keyword after the column name in the ORDER BY clause
Filtering Output Data
As you can see from the output in the preceding section, by default all of the records from the table are displayed The power of the database query comes from displaying only a subset of the data that meets a specific condition The WHERE clause is used to determine what records satisfy the condition of the query This is the meat-and-potatoes of the SELECT command You can use the WHERE clause to break down complex tables to extract specific data For example, you can check for all of the customers that live in Chicago by using the following query:
test=> select "CustomerID", "LastName", "FirstName" from store"Customer" test-> where "City" = 'Gary'; CustomerID | LastName | FirstName + + BLU001 | Blum | Rich (1 row) test=>
Notice that the string literal Gary uses single quotes to signify that it is a string value, while the mixed-case column names require double quotes to preserve the uppercase letters It is easy to get these two things confused
Copyright © OnBarcode.com . All rights reserved.