Resolving generate_series() Parameterization and Cross-Environment Query Failures in SQLite

Issue Overview: generate_series() Produces No Rows in C# Despite Working in SQLStudio

The core issue involves a SQLite query utilizing the generate_series() table-valued function that executes successfully in SQLStudio but returns no rows when run in a C# application after loading the series extension. The query joins the CircuitBreaker table with two generate_series() calls parameterized by column values from CircuitBreaker. When static values replace these dynamic column-based parameters, the query functions correctly in both environments. The discrepancy arises from syntax ambiguities, parameterization logic, and cross-environment differences in SQLite configuration or query execution plans.

Key components of the problem include:

1. Dynamic Parameter Construction: The generate_series(start, end, step) arguments derive from arithmetic operations on columns (e.g., cb.IrMin * cb.Current), introducing runtime evaluation dependencies.
2. Syntax Ambiguities: Misplaced operators or missing delimiters in arithmetic expressions (e.g., cb.IrMax_ cb.Current instead of cb.IrMax * cb.Current) cause parameter misinterpretation.
3. Cross-Environment Behavior: Differences in SQLite versions, extension loading mechanisms, or query optimization strategies between SQLStudio and C# lead to divergent outcomes.

The query’s reliance on implicit joins (comma-separated tables) and column-derived parameters creates fragility that manifests differently across execution contexts.

Possible Causes: Syntax Errors, Parameter Misalignment, and Join Semantics

1. Syntax Errors in Arithmetic Expressions

The original query contains malformed arithmetic expressions in the generate_series() parameters. For example:

generate_series(cb.IrMin _cb.Current, cb.IrMax_ cb.Current, ...)  

Here, the operator between cb.IrMin and cb.Current is missing (likely *), and cb.IrMax_ is mistyped as cb.IrMax with an underscore. Such errors cause SQLite to misinterpret the parameters, leading to invalid ranges or step values.

Why This Causes Failure:

• SQLite’s parser treats cb.IrMin _cb.Current as a single identifier due to the missing operator, resulting in a syntax error or a non-numeric value.
• In environments with stricter parsing (e.g., some C# SQLite drivers), this halts execution entirely, whereas SQLStudio might tolerate or autocorrect the error.

2. Implicit Join Order and Cartesian Product Miscalculations

The query uses implicit cross-joins by listing CircuitBreaker, generate_series(), and another generate_series() in the FROM clause:

FROM CircuitBreaker cb, generate_series(...) gs1, generate_series(...) gs2  

This syntax creates a Cartesian product between CircuitBreaker and both generate_series() calls. However, if either generate_series() call produces zero rows (due to invalid parameters), the entire result set becomes empty.

Why This Causes Failure:

• In C#, the parameterized generate_series() calls might evaluate to empty sets (e.g., invalid start/end/step combinations), while static values avoid this.
• SQLStudio might precompute or cache metadata about the CircuitBreaker columns, allowing generate_series() to resolve parameters correctly, whereas C# evaluates parameters at runtime with stricter type checking.

3. Step Value Sign and Directionality

The step parameter in generate_series() must be negative if the start value is greater than the end value. The original query calculates the step as:

(cb.IrMin * cb.Current - cb.IrMax * cb.Current) / 3  

If IrMin * Current > IrMax * Current, this results in a positive step value, causing generate_series() to return no rows because it cannot increment from a higher start to a lower end.

Why This Causes Failure:

• SQLStudio might implicitly adjust the step sign or tolerate misconfigured ranges, while C# drivers enforce stricter adherence to the generate_series() specification.

Troubleshooting Steps, Solutions & Fixes

1. Validate and Correct Syntax in generate_series() Parameters

Step 1: Identify and Fix Missing Operators
Replace mistyped operators and ensure proper arithmetic syntax:

-- Original (incorrect)  
generate_series(cb.IrMin _cb.Current, cb.IrMax_ cb.Current, ...)  

-- Corrected  
generate_series(cb.IrMin * cb.Current, cb.IrMax * cb.Current, ...)  

Step 2: Verify Parameter Data Types
Ensure that all parameters evaluate to numeric values. Use CAST if necessary:

generate_series(CAST(cb.IrMin AS REAL) * cb.Current, ...)  

2. Explicitly Define Joins and Handle Empty Results

Step 1: Use CROSS JOIN for Clarity
Replace implicit joins with explicit CROSS JOIN syntax to clarify the relationships:

FROM CircuitBreaker cb  
CROSS JOIN generate_series(...) gs1  
CROSS JOIN generate_series(...) gs2  

Step 2: Guard Against Empty generate_series() Output
Use COALESCE or IIF to ensure non-empty ranges:

generate_series(  
  cb.IrMin * cb.Current,  
  cb.IrMax * cb.Current,  
  IIF(cb.IrMin * cb.Current <= cb.IrMax * cb.Current,  
      (cb.IrMax * cb.Current - cb.IrMin * cb.Current) / 3,  
      (cb.IrMin * cb.Current - cb.IrMax * cb.Current) / -3  -- Negative step  
  )  
)  

3. Standardize Step Calculation Logic

Step 1: Compute Step Direction Programmatically
Calculate the step based on the relative values of start and end:

SELECT  
  cb.Name,  
  cb.Current,  
  gs1.value AS IrSet,  
  gs2.value AS IiSet  
FROM CircuitBreaker cb  
CROSS JOIN generate_series(  
  cb.IrMin * cb.Current,  
  cb.IrMax * cb.Current,  
  CASE  
    WHEN cb.IrMin * cb.Current <= cb.IrMax * cb.Current  
    THEN (cb.IrMax * cb.Current - cb.IrMin * cb.Current) / 3  
    ELSE -1 * (cb.IrMin * cb.Current - cb.IrMax * cb.Current) / 3  
  END  
) gs1  
CROSS JOIN generate_series(  
  cb.IiMin * cb.Current,  
  cb.IiMax * cb.Current,  
  CASE  
    WHEN cb.IiMin * cb.Current <= cb.IiMax * cb.Current  
    THEN (cb.IiMax * cb.Current - cb.IiMin * cb.Current) / 5  
    ELSE -1 * (cb.IiMin * cb.Current - cb.IiMax * cb.Current) / 5  
  END  
) gs2  
LIMIT 4;  

4. Debug Cross-Environment Discrepancies

Step 1: Compare SQLite Versions and Extensions
Ensure the C# application uses the same SQLite version and series extension as SQLStudio. Check extension loading:

connection.LoadExtension("series.dll", null);  // Verify path and permissions  

Step 2: Log and Compare Query Execution Plans
Capture the query execution plan in both environments using EXPLAIN QUERY PLAN:

EXPLAIN QUERY PLAN  
SELECT ...;  -- Run in SQLStudio and C#  

Compare the outputs to identify differences in join order or function evaluation.

5. Refactor Query Structure for Reliability

Option 1: Use Subqueries for Parameter Isolation
Isolate generate_series() parameters in subqueries to precompute values:

SELECT  
  cb.Name,  
  cb.Current,  
  gs1.value AS IrSet,  
  gs2.value AS IiSet  
FROM (  
  SELECT  
    *,  
    IrMin * Current AS IrStart,  
    IrMax * Current AS IrEnd,  
    (IrEnd - IrStart) / 3 AS IrStep  
  FROM CircuitBreaker  
) cb  
CROSS JOIN generate_series(IrStart, IrEnd, IrStep) gs1  
CROSS JOIN generate_series(  
  IiMin * Current,  
  IiMax * Current,  
  (IiMax * Current - IiMin * Current) / 5  
) gs2  
LIMIT 4;  

Option 2: Move generate_series() to SELECT Clause
Use generate_series() as a correlated subquery (SQLite 3.30+):

SELECT  
  cb.Name,  
  cb.Current,  
  ir.value AS IrSet,  
  ii.value AS IiSet  
FROM CircuitBreaker cb,  
     generate_series(cb.IrMin * cb.Current, cb.IrMax * cb.Current, ...) ir,  
     generate_series(cb.IiMin * cb.Current, cb.IiMax * cb.Current, ...) ii  
LIMIT 4;  

6. Validate Data Ranges and Step Precision

Step 1: Inspect CircuitBreaker Column Values
Run a diagnostic query to identify invalid ranges:

SELECT  
  IrMin * Current AS IrStart,  
  IrMax * Current AS IrEnd,  
  (IrEnd - IrStart) / 3 AS IrStep,  
  IiMin * Current AS IiStart,  
  IiMax * Current AS IiEnd,  
  (IiEnd - IiStart) / 5 AS IiStep  
FROM CircuitBreaker;  

Ensure IrStart <= IrEnd (or vice versa with negative steps) and that steps are non-zero.

Step 2: Handle Floating-Point Division
Use CAST to avoid integer division truncation:

(CAST(cb.IrMax * cb.Current - cb.IrMin * cb.Current AS REAL) / 3)  

By systematically addressing syntax errors, join semantics, parameter logic, and environmental factors, the query can be stabilized to produce consistent results across SQLStudio and C# applications.