Filtering data : The right way to construct the WHERE clause in a SQL query

Nov 04 2024
1 min read

Introduction

In this blog post, we’ll explore the challenges associated with constructing the WHERE clause in SQL reporting tools like SSRS, Crystal Reports, and others. We will also discuss how Pixel Perfect Reports addresses these challenges by offering a graphical interface for representing filtering conditions. This graphical approach can handle complex filtering scenarios that traditional tools, such as SSRS and Crystal Reports, struggle with.

Problems with the usual approach to construct the WHERE clause

Existing database reporting tools, such as SSRS and Crystal Reports, simply combine individual predicates in the order they are specified in the predicate expression to create the condition clause. This approach works only in trivial cases and cannot handle scenarios involving a combination of AND and OR logic with specific precedence determined by parentheses. In general, the precedence of operations for predicates in a WHERE clause is determined by the parentheses and operator types in the expression, and parentheses can be nested. Therefore, a more sophisticated structure is required to accommodate predicate expressions in their general form.

Filtering in SSRS is accomplished by combining the predicate together.

Pixel Perfect Reports provides the solution

Pixel Perfect Reports provides a graphical interface that allows users to construct filtering conditions, which are then converted into equivalent predicate expressions at runtime as the WHERE clause. The interface includes a pane for building a flowchart. This flowchart consists of logic nodes, one or more predicate nodes, and one or more end nodes. Each predicate node includes an input, an output for when the predicate evaluates to true, and an output for when the predicate evaluates to false. The flowchart can accommodate filtering conditions of arbitrary complexity, meaning that complex predicate expressions with nested parentheses can be easily represented in its graphical form as a corresponding flowchart.

Filtering in Pixel Perfect Reports is accomplished by users constructing a flowchart representing the filtering condition.

Conclusion

Pixel Perfect Reports is the only SQL reporting tool on the market that offers a solution for creating filtering conditions of arbitrary complexity, which can be converted into predicate expressions for use in the WHERE clause.

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