Fix type inference for int64/uint64 (BIGINT) and float64 (DOUBLE)

[vikrantpuppala]

Summary

Fixes type inference bugs for numeric parameters:

• int64/uint64: Were incorrectly mapped to SqlInteger instead of SqlBigInt (fixes #250)
• float64: Was incorrectly mapped to SqlFloat instead of SqlDouble (fixes #314)

Problems Fixed

1. int64/uint64 → BIGINT

When inserting int64/uint64 values into BIGINT columns, the driver was sending them with type INTEGER instead of BIGINT, causing the server to reject large values with error:

[INVALID_PARAMETER_MARKER_VALUE.INVALID_VALUE_FOR_DATA_TYPE] An invalid parameter mapping was provided: 
the value '1311768467463790320' for parameter 'null' cannot be cast to INT because it is malformed.

Additionally, int64 was using strconv.Itoa(int(value)) which truncates values larger than int32.

2. float64 → DOUBLE

When inserting float64 values into DOUBLE columns, the driver was sending them with type FLOAT (32-bit) instead of DOUBLE (64-bit), causing:

• Precision loss for high-precision float64 values
• Potential overflow for values beyond float32 range (~3.4e38)

3. Panic with explicit Parameter type

When using Parameter{Type: SqlBigInt, Value: int64(...)} with a non-string value, the driver panicked at convertNamedValuesToSparkParams due to unsafe type assertion.

Changes

• parameters.go:
  • int64 now uses strconv.FormatInt() and maps to SqlBigInt
  • uint64 now maps to SqlBigInt
  • float64 now maps to SqlDouble instead of SqlFloat
  • Added safe type assertion with fallback in convertNamedValuesToSparkParams

Test plan

• [x] Added unit tests for int64/uint64 type inference (TestParameter_BigInt)
• [x] Added unit tests for float64/float32 type inference (TestParameter_Float)
• [x] Verified large int64 values are correctly inserted and retrieved from BIGINT columns
• [x] Verified float64 values with high precision are correctly inserted and retrieved
• [x] All existing parameter tests pass

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