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barcode generator project source code in vb.net Mathematical Functions in Software
Mathematical Functions PDF 417 Reader In None Using Barcode Control SDK for Software Control to generate, create, read, scan barcode image in Software applications. Paint PDF 417 In None Using Barcode drawer for Software Control to generate, create PDF417 2d barcode image in Software applications. Mathematical functions manipulate numeric values according to mathematical rules. The ROUND function is presented in detail, including an example, followed by a table that lists other mathematical functions that are commonly found in Reading PDF417 In None Using Barcode decoder for Software Control to read, scan read, scan image in Software applications. Create PDF 417 In Visual C#.NET Using Barcode encoder for .NET framework Control to generate, create PDF417 image in VS .NET applications. SQL Demysti ed
PDF417 Encoder In .NET Framework Using Barcode generator for ASP.NET Control to generate, create PDF417 image in ASP.NET applications. PDF 417 Creation In .NET Using Barcode creation for VS .NET Control to generate, create PDF417 2d barcode image in .NET applications. SQL implementations. As always, check your DBMS documentation for a speci c list of supported mathematical functions. PDF417 2d Barcode Encoder In VB.NET Using Barcode printer for VS .NET Control to generate, create PDF417 2d barcode image in Visual Studio .NET applications. Printing GS1  12 In None Using Barcode creation for Software Control to generate, create UPCA Supplement 5 image in Software applications. ROUND
Print Bar Code In None Using Barcode generator for Software Control to generate, create bar code image in Software applications. Encoding Data Matrix ECC200 In None Using Barcode generation for Software Control to generate, create Data Matrix ECC200 image in Software applications. The ROUND function rounds off a number to the speci ed number of decimal places. The number is provided as the rst expression and the number of decimal places as the second. The general format of the ROUND function is shown next, followed by an example adapted from earlier in the chapter. Paint Bar Code In None Using Barcode creator for Software Control to generate, create bar code image in Software applications. UPC  13 Generation In None Using Barcode creator for Software Control to generate, create EAN13 image in Software applications. ROUND (numeric_expression,number_of_decimal_places) Encode ISSN  13 In None Using Barcode creator for Software Control to generate, create ISSN  13 image in Software applications. Making EAN13 In VS .NET Using Barcode encoder for ASP.NET Control to generate, create EAN13 Supplement 5 image in ASP.NET applications. What is the average cost of a copy of The Last Samurai, rounded to the nearest penny
ECC200 Creation In Visual Studio .NET Using Barcode printer for Reporting Service Control to generate, create ECC200 image in Reporting Service applications. Create DataMatrix In Visual C# Using Barcode creation for VS .NET Control to generate, create ECC200 image in .NET framework applications. SELECT ROUND((RETAIL_PRICE_VHS + RETAIL_PRICE_DVD) / 2, 2) AS AVG_COST FROM MOVIE WHERE MOVIE_TITLE = 'The Last Samurai'; AVG_COST 17.96 Matrix 2D Barcode Creator In .NET Using Barcode creator for ASP.NET Control to generate, create 2D Barcode image in ASP.NET applications. Making Barcode In None Using Barcode maker for Font Control to generate, create bar code image in Font applications. Other Mathematical Functions
Recognizing Code 128 Code Set B In Visual Basic .NET Using Barcode decoder for .NET Control to read, scan read, scan image in Visual Studio .NET applications. Code39 Decoder In Java Using Barcode reader for Java Control to read, scan read, scan image in Java applications. The table that follows lists the most commonly found mathematical functions. The general syntax for all of them is the same: FUNCTION_NAME(expression) Function ABS COS EXP POWER SIN TAN Description Absolute value of the given number Trigonometric cosine of the given angle (in radians) Exponential value of the given number Raise number to a power (both number and power are parameters) Trigonometric sine of the given angle (in radians) Trigonometric tangent of the given angle (in radians) Conversion Functions
Conversion functions convert data from one data type to another.
Retrieving Data Using Data Query Language
CAST
The CAST function converts data from one data type to another. Note, however, that it is not yet supported by DB2. Here is the general syntax of the CAST function, followed by an example: CAST (expression AS data_type) List the DVD price of The Last Samurai with a leading dollar sign. The numeric value must be converted to (cast as) a character string so that you can concatenate it with a literal containing a dollar sign. Note that for Microsoft SQL Server, the concatenation operator in the statement has to be changed from  to + . SELECT '$'  CAST(RETAIL_PRICE_DVD AS VARCHAR(6)) AS PRICE FROM MOVIE WHERE MOVIE_TITLE = 'The Last Samurai'; PRICE $19.96 CONVERT TO
Many DBMS implementations offer a CONVERT or CONVERT TO function. However, the CAST function is generally recommended instead because it is implemented in a more standard way across vendors. Aggregate Functions and Grouping Rows
An aggregate function is a function that combines multiple rows of data together into a single row. The following table shows aggregate functions that are supported in most SQL implementations: Function Name AVG COUNT Description Calculates the average value for a column or expression. Counts the number of values found in a column. The DISTINCT keyword can be used to count the number of unique values instead of the total number of values (rows) in a column. Finds the maximum value in a column. Finds the minimum value in a column. Sums (totals up) the values in a column. MAX MIN SUM
Here are some examples: SQL Demysti ed
What is the average price of a DVD Notice that the ROUND and AVG functions are nested so you get the result in dollars and cents. SELECT ROUND(AVG(RETAIL_PRICE_DVD),2) AS AVG_PRICE FROM MOVIE; AVG_PRICE 24.67 How many movies are in the MOVIE table
SELECT COUNT(*) AS NUM_MOVIES FROM MOVIE; NUM_MOVIES 20 How many different movie genres are represented in the MOVIE table Notice the use of DISTINCT so the DBMS counts unique values of MOVIE_GENRE_CODE. SELECT COUNT(DISTINCT(MOVIE_GENRE_CODE)) AS NUM_GENRES FROM MOVIE NUM_GENRES 5 What is the shortest and longest movie title Notice the nesting of the LENGTH function with the MIN and MAX functions. This version works in Oracle, DB2, and MySQL (change LENGTH to LEN for Microsoft SQL Server and Sybase). SELECT MIN(LENGTH(MOVIE_TITLE)) AS MIN_LENGTH, MAX(LENGTH(MOVIE_TITLE)) AS MAX_LENGTH FROM MOVIE; MIN_LENGTH MAX_LENGTH  7 54 Retrieving Data Using Data Query Language
GROUP BY Clause
As you have seen, if you use an aggregate function by itself in a query, you get one row back for the entire query. This makes sense because there is no way for the RDBMS to know what other result you might want, unless you tell it, which is the very purpose of the GROUP BY clause. It tells the DBMS to form the rows selected by the query into groups based on the values of one or more columns and to apply the aggregate function(s) to each group, returning one row for each group in the result set. This is much like asking for subtotals by department instead of one grand total for an entire company, but as you have seen, aggregate functions can do much more than just add things up. By the way, the DBMS will sort the rows selected by the query on the columns listed in the GROUP BY clause (so it can group them easily), so the groups will be returned in ascending sequence unless you add an ORDER BY that speci es another sequence. Here is an example: List each movie genre code with the number of movies that are assigned to it. SELECT MOVIE_GENRE_CODE AS GENRE, COUNT(*) AS COUNT FROM MOVIE GROUP BY MOVIE_GENRE_CODE; GENRE COUNT  ActAd 7 Comdy 4 Drama 6 Forgn 1 Rmce 2 What happens if you leave the GROUP BY clause out of this query The DBMS returns an error message, and unfortunately, the error message is often quite cryptic. Most newcomers to SQL have dif culty understanding the problem, but without the GROUP BY clause, the query is illogical. The COUNT(*) function is an aggregate function, so without a GROUP BY, it returns a single row of data. However, the MOVIE_GENRE_CODE is a column and without being named in a GROUP BY, the query will return the value from every row in the table. Without the GROUP BY to correlate the two, the DBMS does not know what to do. No wonder some people call them aggravating functions instead of aggregate functions. But it really isn t that dif cult. Just remember one rule: Whenever a query includes an aggregate function, then every column in the query results must either be formed using an aggregate function or be named in the GROUP BY clause.

