barcode generator in vb.net 2005 Retrieving Data in Software

Printer Denso QR Bar Code in Software Retrieving Data

Retrieving Data
Recognizing QR-Code In None
Using Barcode Control SDK for Software Control to generate, create, read, scan barcode image in Software applications.
QR Maker In None
Using Barcode generator for Software Control to generate, create QR image in Software applications.
You would expect the two expressions
QR Code Reader In None
Using Barcode reader for Software Control to read, scan read, scan image in Software applications.
QR-Code Creator In C#.NET
Using Barcode drawer for .NET Control to generate, create QR Code JIS X 0510 image in VS .NET applications.
(SUM(SALES) SUM(QUOTA)) AND SUM(SALES QUOTA)
Denso QR Bar Code Creator In .NET Framework
Using Barcode encoder for ASP.NET Control to generate, create Denso QR Bar Code image in ASP.NET applications.
Denso QR Bar Code Drawer In Visual Studio .NET
Using Barcode generation for VS .NET Control to generate, create Denso QR Bar Code image in .NET framework applications.
in the select list to produce identical results, but the example shows that they do not. The salesperson with a NULL value in the QUOTA column is again the reason. The expression
Denso QR Bar Code Generator In Visual Basic .NET
Using Barcode encoder for .NET Control to generate, create QR Code JIS X 0510 image in Visual Studio .NET applications.
Create Code 39 In None
Using Barcode encoder for Software Control to generate, create ANSI/AIM Code 39 image in Software applications.
SUM(SALES)
Encoding UPC Code In None
Using Barcode maker for Software Control to generate, create GS1 - 12 image in Software applications.
Bar Code Drawer In None
Using Barcode creation for Software Control to generate, create barcode image in Software applications.
totals the sales for all ten salespeople, while the expression
Encoding Data Matrix 2d Barcode In None
Using Barcode generator for Software Control to generate, create DataMatrix image in Software applications.
EAN13 Maker In None
Using Barcode encoder for Software Control to generate, create EAN / UCC - 13 image in Software applications.
SUM(QUOTA)
Monarch Creator In None
Using Barcode generator for Software Control to generate, create 2 of 7 Code image in Software applications.
Make 1D Barcode In VB.NET
Using Barcode creator for .NET Control to generate, create 1D Barcode image in .NET applications.
totals only the nine non-NULL quota values. The expression
Matrix 2D Barcode Printer In .NET
Using Barcode creator for VS .NET Control to generate, create Matrix Barcode image in .NET framework applications.
Draw ECC200 In None
Using Barcode maker for Online Control to generate, create Data Matrix image in Online applications.
SUM(SALES) SUM(QUOTA)
Encode DataBar In Java
Using Barcode encoder for Java Control to generate, create GS1 DataBar image in Java applications.
Encoding USS Code 128 In Java
Using Barcode creator for Android Control to generate, create Code 128A image in Android applications.
computes the difference of these two amounts. However, the column function
Generate Code39 In Visual C#.NET
Using Barcode printer for .NET Control to generate, create Code-39 image in .NET framework applications.
Bar Code Generation In Java
Using Barcode printer for BIRT reports Control to generate, create bar code image in BIRT applications.
SUM(SALES QUOTA)
has a non-NULL argument value for only nine of the ten salespeople. In the row with a NULL quota value, the subtraction produces a NULL, which is ignored by the SUM() function. Thus, the sales for the salesperson without a quota, which are included in the previous calculation, are excluded from this calculation. Which is the correct answer Both are! The first expression calculates exactly what it says: the sum of SALES, less the sum of QUOTA. The second expression also calculates exactly what it says: the sum of (SALES QUOTA). When NULL values occur, however, the two calculations are not quite the same. The ANSI/ISO SQL standard specifies these precise rules for handling NULL values in column functions: If any of the data values in a column are NULL, they are ignored for the purpose of computing the column function s value. If every data item in the column is NULL, then the SUM(), AVG(), MIN(), and MAX() column functions return a NULL value; the COUNT() function returns a value of zero. If no data items are in the column (that is, the column is empty), then the SUM(), AVG(), MIN(), and MAX() column functions return a NULL value; the COUNT() function returns a value of zero. The COUNT(*) counts rows and does not depend on the presence or absence of NULL values in a column. If there are no rows, it returns a value of zero. Although the standard is very clear in this area, commercial SQL products may produce results different from the standard, especially if all of the data values in a column are NULL or when a column function is applied to an empty table. Before assuming it will behave as specified by the standard, you should test your particular DBMS.
8:
Summary Queries
Duplicate Row Elimination (DISTINCT)
Recall from 6 that you can specify the DISTINCT keyword at the beginning of the select list to eliminate duplicate rows of query results. You can also ask SQL to eliminate duplicate values from a column before applying a column function to it. To eliminate duplicate values, the keyword DISTINCT is included before the column function argument, immediately after the opening parenthesis. Here are two queries that illustrate duplicate row elimination for column functions: How many different titles are held by salespeople
SELECT COUNT(DISTINCT TITLE) FROM SALESREPS; COUNT(DISTINCT TITLE) ---------------------3
PART II
How many sales offices have salespeople who are over quota
SELECT COUNT(DISTINCT REP_OFFICE) FROM SALESREPS WHERE SALES > QUOTA; COUNT(DISTINCT REP_OFFICE) --------------------------4
The DISTINCT keyword can be specified only once in a query. If it appears in the argument of one column function, it can t appear in any other. If it is specified before the select list, it can t appear in any column functions. The only exception is that DISTINCT may be specified a second time inside a subquery (contained within the query). Subqueries are described in 9.
Grouped Queries (GROUP BY Clause)
The summary queries described thus far are like the totals at the bottom of a report. They condense all of the detailed data in the report into a single, summary row of data. Just as subtotals are useful in printed reports, it s often convenient to summarize query results at a subtotal level. The GROUP BY clause of the SELECT statement provides this capability. The function of the GROUP BY clause is most easily understood by example. Consider these two queries: What is the average order size
SELECT AVG(AMOUNT) FROM ORDERS; AVG(AMOUNT) -----------$8,256.37
Part II:
Copyright © OnBarcode.com . All rights reserved.