Fix unable to recursive parsing the UNION clause

[git-hulk]

This closes #93

[coveralls]

Pull Request Test Coverage Report for Build 10629722228

Details

• 1 of 1 (100.0%) changed or added relevant line in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.04%) to 59.386%

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Totals
Change from base Build 10570485618:	0.04%
Covered Lines:	6156
Relevant Lines:	10366

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💛 - Coveralls

[git-hulk]

@Lance726 The root cause parseSelectQuery will recursively parse the UNION clause but parseSelectStatment would limit to the SELECT clause only.

[Lance726]

@Lance726 The root cause parseSelectQuery will recursively parse the UNION clause but parseSelectStatment would limit to the SELECT clause only.

OK, get it !