Support CREATE [ { TEMPORARY | TEMP } ] SEQUENCE [ IF NOT EXISTS ] <sequence_name>

[samjay000]

Create statement for CREATE [ { TEMPORARY | TEMP } ] SEQUENCE [ IF NOT EXISTS ] <sequence_name>

This is continuation of #673

[coveralls]

Pull Request Test Coverage Report for Build 3284263174

• 22 of 28 (78.57%) changed or added relevant lines in 3 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.02%) to 85.83%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/parser.rs	7	9	77.78%
src/ast/mod.rs	6	10	60.0%

Totals
Change from base Build 3255613260:	-0.02%
Covered Lines:	10782
Relevant Lines:	12562

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💛 - Coveralls

[alamb]

LGTM -- thank you @sam-mmm