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create barcode using vb.net CAT DURATION --- -------BLD 4 BLD 1 BLD 2 DSG 2 in Java
CAT DURATION --- -------BLD 4 BLD 1 BLD 2 DSG 2 Data Matrix Drawer In Java Using Barcode generator for Android Control to generate, create ECC200 image in Android applications. www.OnBarcode.comBarcode Maker In Java Using Barcode generator for Android Control to generate, create Barcode image in Android applications. www.OnBarcode.comIn this example, you can see that the OR operator in SQL is inclusive; otherwise, the third row wouldn t show up in the result. The XML course belongs to the BLD course category (so the first condition evaluates to TRUE) and its duration is two days (so the second condition also evaluates to TRUE). Another point of note regarding the evaluation order for an OR operator is that conditions are evaluated in order until a TRUE condition is found. All subsequent conditions are ignored. This is due to the fact that for an OR operator to be satisfied, only one condition must evaluate to TRUE. So, even if you had many OR conditions, evaluation will stop as soon as the first TRUE occurs. In the upcoming discussion of the NOT operator, you will see how to construct an exclusive OR. GS1 - 13 Maker In Java Using Barcode creation for Android Control to generate, create EAN 13 image in Android applications. www.OnBarcode.comPDF 417 Maker In Java Using Barcode creator for Android Control to generate, create PDF417 image in Android applications. www.OnBarcode.comThe AND Operator and Operator Precedence Issues
Make Code 39 Full ASCII In Java Using Barcode maker for Android Control to generate, create Code 39 image in Android applications. www.OnBarcode.comBarcode Maker In Java Using Barcode creation for Android Control to generate, create Barcode image in Android applications. www.OnBarcode.comThere is a possible problem if your compound conditions contain a mixture of AND and OR operators. See Listing 4-18 for an experiment with a query against the DUAL table. Listing 4-18. Combining Conditions with OR and AND select 'is true ' as condition from dual where 1=1 or 1=0 and 0=1; CONDITION --------is true The compound condition in Listing 4-18 consists of three rather trivial, simple conditions, evaluating to TRUE, FALSE, and FALSE, respectively. But what is the outcome of the compound predicate as a whole, and why Apparently, the compound predicate evaluates to TRUE; otherwise, Listing 4-18 would have returned the message no rows selected. In such cases, the result depends on the operator precedence rules. You can interpret the condition of Listing 4-18 in two ways, as follows: Drawing Barcode In Java Using Barcode drawer for Android Control to generate, create Barcode image in Android applications. www.OnBarcode.comCreate USPS PLANET Barcode In Java Using Barcode creation for Android Control to generate, create Planet image in Android applications. www.OnBarcode.comRETRIEVAL: THE BASICS
Creating DataMatrix In Java Using Barcode maker for Android Control to generate, create Data Matrix 2d barcode image in Android applications. www.OnBarcode.comData Matrix Generation In Objective-C Using Barcode creation for iPad Control to generate, create Data Matrix 2d barcode image in iPad applications. www.OnBarcode.com1=1 OR ... AND 0=1
Read Barcode In Visual Basic .NET Using Barcode scanner for .NET framework Control to read, scan read, scan image in .NET applications. www.OnBarcode.comPDF417 Scanner In Visual C# Using Barcode decoder for Visual Studio .NET Control to read, scan read, scan image in .NET applications. www.OnBarcode.comIf one of the operands of OR is true, the overall result is TRUE. If one of the operands of AND is false, the overall result is FALSE. Generating UCC-128 In Java Using Barcode creation for Java Control to generate, create UCC-128 image in Java applications. www.OnBarcode.comScanning QR Code JIS X 0510 In C#.NET Using Barcode reader for .NET framework Control to read, scan read, scan image in VS .NET applications. www.OnBarcode.comListing 4-18 obviously shows an overall result of TRUE. The Oracle DBMS evaluates the expressions in the order that will require the fewest conditional checks. This decision is based on the demographics of your data and is an advanced topic not covered in this book. With compound conditions, it is always better to use parentheses to indicate the order in which you want the operations to be performed, rather than relying on implicit language precedence rules. Listing 4-19 shows two variants of the query from Listing 4-18, using parentheses in the WHERE clause. Listing 4-19. Using Parentheses to Force Operator Precedence select 'is true ' as condition from dual where (1=1 or 1=0) and 0=1; no rows selected select 'is true ' as condition from dual where 1=1 or (1=0 and 0=1); CONDITION --------is true Barcode Encoder In None Using Barcode generator for Software Control to generate, create Barcode image in Software applications. www.OnBarcode.comUniversal Product Code Version A Scanner In None Using Barcode reader for Software Control to read, scan read, scan image in Software applications. www.OnBarcode.comCaution Remember that you can use white space to beautify your SQL commands; however, never allow an attractive SQL command layout (for example, with suggestive indentations) to confuse you. Tabs, spaces, and new lines may increase statement readability, but they don t change the meaning of your SQL statements in any way. GTIN - 12 Creation In None Using Barcode creation for Word Control to generate, create Universal Product Code version A image in Word applications. www.OnBarcode.comUniversal Product Code Version A Creation In Visual Studio .NET Using Barcode generator for Visual Studio .NET Control to generate, create UPC-A Supplement 5 image in Visual Studio .NET applications. www.OnBarcode.comThe NOT Operator
Draw Code 39 Full ASCII In None Using Barcode printer for Online Control to generate, create Code 3/9 image in Online applications. www.OnBarcode.comReading EAN-13 Supplement 5 In Java Using Barcode recognizer for Java Control to read, scan read, scan image in Java applications. www.OnBarcode.comYou can apply the NOT operator to any arbitrary condition to negate that condition. Listing 4-20 shows an example. RETRIEVAL: THE BASICS
Listing 4-20. Using the NOT Operator to Negate Conditions select ename, job, deptno from employees where NOT deptno > 10; ENAME -------CLARK KING MILLER JOB DEPTNO -------- -------MANAGER 10 DIRECTOR 10 ADMIN 10 In this simple case, you could achieve the same effect by removing the NOT operator and changing the comparison operator > into <=, as shown in Listing 4-21. Listing 4-21. Equivalent Query Without Using the NOT Operator select ename, job, deptno from employees where deptno <= 10; ENAME -------CLARK KING MILLER JOB DEPTNO -------- -------MANAGER 10 DIRECTOR 10 ADMIN 10 The NOT operator becomes more interesting and useful in cases where you have complex compound predicates with AND, OR, and parentheses. In such cases, the NOT operator gives you more control over the correctness of your commands. In general, the NOT operator should be placed in front of the condition. Listing 4-22 shows an example of illegal syntax and a typical error message when NOT is positioned incorrectly. Listing 4-22. Using the NOT Operator in the Wrong Place ename, job, deptno employees deptno NOT > 10; deptno NOT > 10 * ERROR at line 3: ORA-00920: invalid relational operator There are some exceptions to this rule. As you will see in Section 4.6, the SQL operators BETWEEN, IN, and LIKE have their own built-in negation option. select from where where
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