barcode generator in vb.net 2005 (A UNION ALL B) UNION C in Software

Creation QR-Code in Software (A UNION ALL B) UNION C

(A UNION ALL B) UNION C
Denso QR Bar Code Decoder In None
Using Barcode Control SDK for Software Control to generate, create, read, scan barcode image in Software applications.
Generating QR In None
Using Barcode drawer for Software Control to generate, create Quick Response Code image in Software applications.
then it produces only four rows, because the outer UNION eliminates all duplicate rows. For this reason, it s always a good idea to use parentheses in UNIONs of three or more tables to specify the order of evaluation intended.
QR Code ISO/IEC18004 Reader In None
Using Barcode decoder for Software Control to read, scan read, scan image in Software applications.
QR Code Creator In Visual C#
Using Barcode generator for VS .NET Control to generate, create QR Code image in VS .NET applications.
Summary
QR Code 2d Barcode Encoder In .NET Framework
Using Barcode generator for ASP.NET Control to generate, create QR Code ISO/IEC18004 image in ASP.NET applications.
QR Code JIS X 0510 Generator In Visual Studio .NET
Using Barcode creator for .NET Control to generate, create Denso QR Bar Code image in Visual Studio .NET applications.
This chapter is the first of four chapters about SQL queries. It described the following query features: The SELECT statement is used to express a SQL query. Every SELECT statement produces a table of query results containing one or more columns and zero or more rows. The FROM clause specifies the table(s) containing the data to be retrieved by a query. The SELECT clause specifies the column(s) of data to be included in the query results, which can be columns of data from the database, or calculated columns. The WHERE clause selects the rows to be included in the query results by applying a search condition to rows of the database. A search condition can select rows by comparing values, by checking a value against a range or set of values, by matching a string pattern, and by checking for NULL values. Simple search conditions can be combined with AND, OR, and NOT to form more complex search conditions. The ORDER BY clause specifies that the query results should be sorted in ascending or descending order, based on the values of one or more columns. The UNION operation can be used within a SELECT statement to combine two or more sets of query results into a single set.
Drawing QR Code In Visual Basic .NET
Using Barcode encoder for .NET framework Control to generate, create QR Code ISO/IEC18004 image in .NET framework applications.
USS-128 Creation In None
Using Barcode creator for Software Control to generate, create GS1 128 image in Software applications.
CHAPTER
Data Matrix ECC200 Generator In None
Using Barcode drawer for Software Control to generate, create DataMatrix image in Software applications.
Code 128B Creator In None
Using Barcode creator for Software Control to generate, create Code 128 Code Set C image in Software applications.
Multitable Queries (Joins)
Generating Barcode In None
Using Barcode encoder for Software Control to generate, create bar code image in Software applications.
EAN13 Maker In None
Using Barcode drawer for Software Control to generate, create European Article Number 13 image in Software applications.
ost useful queries request data from two or more tables in a database. For example, these requests for data in the sample database draw data from two, three, and four tables respectively:
UPC - 8 Printer In None
Using Barcode encoder for Software Control to generate, create European Article Number 8 image in Software applications.
EAN 128 Drawer In None
Using Barcode maker for Online Control to generate, create EAN128 image in Online applications.
List the salespeople and the offices where they work (SALESREPS and OFFICES tables). List each order placed last week, showing the order amount, the name of the customer who placed it, and the name of the product ordered (ORDERS, CUSTOMERS, and PRODUCTS tables). Show all orders taken by salespeople in the Eastern region, showing the product description and salesperson (ORDERS, SALESREPS, OFFICES, and PRODUCTS tables).
Scan Barcode In Visual Basic .NET
Using Barcode scanner for .NET framework Control to read, scan read, scan image in .NET applications.
Recognize Bar Code In Visual C#
Using Barcode reader for VS .NET Control to read, scan read, scan image in .NET framework applications.
SQL allows you to retrieve data that answers these requests through multitable queries that join data from two or more tables. These queries and the SQL join facility are described in this chapter. We begin with the join capabilities that have been a part of SQL from the earliest days and are found in all SQL products today. The later sections describe additional join capabilities that first appeared in SQL2 standard and are found in most mainstream products.
Printing GS1 - 12 In Visual Studio .NET
Using Barcode creation for Visual Studio .NET Control to generate, create GTIN - 12 image in Visual Studio .NET applications.
Code39 Printer In .NET Framework
Using Barcode drawer for .NET framework Control to generate, create Code 39 Extended image in .NET framework applications.
A Two-Table Query Example
Barcode Encoder In .NET Framework
Using Barcode creation for Reporting Service Control to generate, create bar code image in Reporting Service applications.
Encoding Barcode In Visual C#
Using Barcode encoder for .NET framework Control to generate, create bar code image in Visual Studio .NET applications.
The best way to understand the facilities that SQL provides for multitable queries is to start with a simple request that combines data from two different tables: List all orders, showing the order number and amount, and the name and credit limit of the customer who placed it. The four specific data items requested are clearly stored in two different tables, as shown in Figure 7-1. The ORDERS table contains the order number and amount of each order, but doesn t have customer names or credit limits. The CUSTOMERS table contains the customer names and credit limits, but it lacks any information about orders.
Part II:
Retrieving Data
Primary key/ foreign key relationship
ORDERS Table ORDER_NUM ORDER_DATE 112961 113012 112989 17-DEC-89 11-JAN-90 03-JAN-90
CUST 2117 2111 2101
REP 106 105 106
QTY 7 35 6
AMOUNT $31,500.00 $3,745.00 $1,458.00
List each order, showing the order number and amount, and the name and credit limit of the customer who placed it CUSTOMERS Table CUST_NUM COMPANY 2108 Holm & Landis 2117 J.P. Sinclair 2122 Three-Way Lines
CUST_REP
CREDIT_LIMIT
109 106 105
$55,000.00 $35,000.00 $30,000.00
FIGURE 7-1
A request that spans two tables
There is a link between these two tables, however. In each row of the ORDERS table, the CUST column contains the customer number of the customer who placed the order, which matches the value in the CUST_NUM column in one of the rows in the CUSTOMERS table. Clearly, the SELECT statement that handles the request must somehow use this link between the tables to generate its query results. Before examining the SELECT statement for the query, it s instructive to think about how you would manually handle the request, using paper and pencil. Figure 7-2 shows what you would probably do: 1. Start by writing down the four column names for the query results. Then move to the ORDERS table, and start with the first order. 2. Look across the row to find the order number (112961) and the order amount ($31,500.00), and copy both values to the first row of query results. 3. Look across the row to find the number of the customer who placed the order (2117), and move to the CUSTOMERS table to find customer number 2117 by searching the CUST_NUM column. 4. Move across the row of the CUSTOMERS table to find the customer s name ( J.P. Sinclair ) and credit limit ($35,000.00), and copy them to the query results table. 5. You ve generated a row of query results! Move back to the ORDERS table, and go to the next row. Repeat the process, starting with Step 2, until you run out of orders.
7:
Multitable Queries (Joins)
CUSTOMERS Table CUST_NUM COMPANY 2108 Holm & Landis 2117 J.P. Sinclair 2122 Three-Way Lines
Copyright © OnBarcode.com . All rights reserved.