Refactor CreateTable.columns from Vec<ColumnDef> to Option<Vec<ColumnDef>>

[devgony]

Goal

# core/src/ast/mod.rs
CreateTable {                                                                                     
    if_not_exists: bool,                                                                          
    name: String,                                                                                 
    Optional schema                                                                           
-  columns: Vec<ColumnDef>,
+  columns: Option<Vec<ColumnDef>>,
    source: Option<Box<Query>>,                                                                   
    engine: Option<String>,                                                                       
},                          

Todo

Refactor CreateTable.columns from Vec<ColumnDef> to Option<Vec<ColumnDef>>

Next

• implement from_ddl()

[coveralls]

Pull Request Test Coverage Report for Build 4133443138

• 61 of 62 (98.39%) changed or added relevant lines in 6 files are covered.
• 48 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.06%) to 98.548%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
core/src/executor/execute.rs	9	10	90.0%

Files with Coverage Reduction	New Missed Lines	%
core/src/executor/evaluate/stateless.rs	15	94.09%
core/src/executor/aggregate/mod.rs	33	83.33%

Totals
Change from base Build 4110793318:	-0.06%
Covered Lines:	39438
Relevant Lines:	40019

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💛 - Coveralls

[panarch]

Thanks for the good catch! All looks good :D