>It may not be necessary, but if there is a simple rule like where clause should exactly match index expression it's easier to build apps. Remembering the intricate details of what is necessary in this case versus that case is the definition of steep learning curve.
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Sure, if it is easier for you then you may write SQL this way. However, the SQL I've used follows the rule, it is just the rule isn't exactly what you think it is. VFP doesn't compare the text, it compares byte code and it doesn't require exact match for the byte code either. For example, literals "String" and 'String' are compiled to different byte code, but expressions are considered equal, etc.