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version 1.1.2.2, 2001/12/03 00:08:00
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version 1.6, 2005/02/05 23:00:52
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| //%///////////////////////////////////////////////////////////////////////////// |
//%2005//////////////////////////////////////////////////////////////////////// |
| // | // |
| // Copyright (c) 2000, 2001 BMC Software, Hewlett-Packard Company, IBM, |
// Copyright (c) 2000, 2001, 2002 BMC Software; Hewlett-Packard Development |
| // The Open Group, Tivoli Systems |
// Company, L.P.; IBM Corp.; The Open Group; Tivoli Systems. |
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// Copyright (c) 2003 BMC Software; Hewlett-Packard Development Company, L.P.; |
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// IBM Corp.; EMC Corporation, The Open Group. |
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// Copyright (c) 2004 BMC Software; Hewlett-Packard Development Company, L.P.; |
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// IBM Corp.; EMC Corporation; VERITAS Software Corporation; The Open Group. |
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// Copyright (c) 2005 Hewlett-Packard Development Company, L.P.; IBM Corp.; |
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// EMC Corporation; VERITAS Software Corporation; The Open Group. |
| // | // |
| // Permission is hereby granted, free of charge, to any person obtaining a copy | // Permission is hereby granted, free of charge, to any person obtaining a copy |
| // of this software and associated documentation files (the "Software"), to | // of this software and associated documentation files (the "Software"), to |
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| PEGASUS_NAMESPACE_BEGIN | PEGASUS_NAMESPACE_BEGIN |
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/** Represents SQL where clause operators. |
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These operators include the following: |
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<ul> |
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<li>OR</li> |
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<li>AND</li> |
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<li>NOT</li> |
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<li>=</li> |
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<li><></li> |
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<li><</li> |
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<li>≤</li> |
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<li>></li> |
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<li>≥</li> |
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<li>IS NULL</li> |
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<li>IS NOT NULL</li> |
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<li>IS TRUE</li> |
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<li>IS NOT TRUE</li> |
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<li>IS FALSE</li> |
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<li>IS NOT FALSE</li> |
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</ul> |
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Here's an example of a SQL query that uses some of these operations. |
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<pre> |
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SELECT * |
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FROM MyClass |
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WHERE (x > 10 OR y ≤ 1.5) OR z = 19 AND name IS NOT NULL |
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</pre> |
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As the parser recognizes these operations, it adds the corresponding |
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WQLOperation enumeration tag to the WQLSelectStatement by calling |
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WQLSelectStatement::appendOperation(). |
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Operators may be converted to string by calling WQLOperationToString(). |
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Note that in expressions like this one: |
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<pre> |
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count IS TRUE |
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</pre> |
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The IS operator is NOT treated as a binary operator (which would take |
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count and TRUE as its operands). Instead, the IS operator and TRUE operand |
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are combined to form a single unary operation called "IS_TRUE". In this |
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way, evaluation may be implemented by more efficiently (the TRUE operand |
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is eliminated and therefore need not be handled). Conceptually, the above |
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expression is equivalent to the following psuedo expression: |
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<pre> |
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IS_TRUE(count) |
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</pre> |
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Note that this technique is applied the following operations (also |
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combined to be unary operations). |
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<ul> |
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<li>WQL_IS_NULL</li> |
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<li>WQL_IS_NOT_NULL</li> |
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<li>WQL_IS_TRUE</li> |
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<li>WQL_IS_NOT_TRUE</li> |
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<li>WQL_IS_FALSE</li> |
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<li>WQL_IS_NOT_FALSE</li> |
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</ul> |
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*/ |
| enum WQLOperation | enum WQLOperation |
| { | { |
| WQL_OR, | WQL_OR, |
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| WQL_GT, | WQL_GT, |
| WQL_GE, | WQL_GE, |
| WQL_IS_NULL, | WQL_IS_NULL, |
| WQL_IS_TRUE, |
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| WQL_IS_FALSE, |
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| WQL_IS_NOT_NULL, | WQL_IS_NOT_NULL, |
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WQL_IS_TRUE, |
| WQL_IS_NOT_TRUE, | WQL_IS_NOT_TRUE, |
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WQL_IS_FALSE, |
| WQL_IS_NOT_FALSE | WQL_IS_NOT_FALSE |
| }; | }; |
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Return to
WQLOperation.h
CVS log
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