CREATE TABLE tbl AS SELECT should return get_alias() for its column

[chezou]

Currently, CREATE TABLE AS SELECT a.k.a. CTAS doesn't parse column aliases with functions e.g., coalesce, if, appropriately.

In the following example, coalesce is parsed as Name while it should be Function to get get_alias() appropriately.

Before

>>> import sqlparse
>>> p = sqlparse.parse('CREATE TABLE tbl1 AS SELECT coalesce(t1.col1, 0) AS col1 FROM t1')[0]
>>> p._pprint_tree()
|- 0 DDL 'CREATE'
|- 1 Whitespace ' '
|- 2 Keyword 'TABLE'
|- 3 Whitespace ' '
|- 4 Identifier 'tbl1'
|  `- 0 Name 'tbl1'
|- 5 Whitespace ' '
|- 6 Keyword 'AS'
|- 7 Whitespace ' '
|- 8 DML 'SELECT'
|- 9 Whitespace ' '
|- 10 Identifier 'coales...'
|  |- 0 Name 'coales...'
|  `- 1 Identifier '(t1.co...'
|     |- 0 Parenthesis '(t1.co...'
|     |  |- 0 Punctuation '('
|     |  |- 1 IdentifierList 't1.col...'
|     |  |  |- 0 Identifier 't1.col1'
|     |  |  |  |- 0 Name 't1'
|     |  |  |  |- 1 Punctuation '.'
|     |  |  |  `- 2 Name 'col1'
|     |  |  |- 1 Punctuation ','
|     |  |  |- 2 Whitespace ' '
|     |  |  `- 3 Integer '0'
|     |  `- 2 Punctuation ')'
|     |- 1 Whitespace ' '
|     |- 2 Keyword 'AS'
|     |- 3 Whitespace ' '
|     `- 4 Identifier 'col1'
|        `- 0 Name 'col1'
|- 11 Whitespace ' '
|- 12 Keyword 'FROM'
|- 13 Whitespace ' '
`- 14 Identifier 't1'
   `- 0 Name 't1'
>>> p.tokens[10].get_alias()
# Should return 'col1'

After

>>> p = sqlparse.parse('CREATE TABLE tbl1 AS SELECT coalesce(t1.col1, 0) AS col1 FROM t1')[0]
>>> p._pprint_tree()
|- 0 DDL 'CREATE'
|- 1 Whitespace ' '
|- 2 Keyword 'TABLE'
|- 3 Whitespace ' '
|- 4 Identifier 'tbl1'
|  `- 0 Name 'tbl1'
|- 5 Whitespace ' '
|- 6 Keyword 'AS'
|- 7 Whitespace ' '
|- 8 DML 'SELECT'
|- 9 Whitespace ' '
|- 10 Identifier 'coales...'
|  |- 0 Function 'coales...'
|  |  |- 0 Identifier 'coales...'
|  |  |  `- 0 Name 'coales...'
|  |  `- 1 Parenthesis '(t1.co...'
|  |     |- 0 Punctuation '('
|  |     |- 1 IdentifierList 't1.col...'
|  |     |  |- 0 Identifier 't1.col1'
|  |     |  |  |- 0 Name 't1'
|  |     |  |  |- 1 Punctuation '.'
|  |     |  |  `- 2 Name 'col1'
|  |     |  |- 1 Punctuation ','
|  |     |  |- 2 Whitespace ' '
|  |     |  `- 3 Integer '0'
|  |     `- 2 Punctuation ')'
|  |- 1 Whitespace ' '
|  |- 2 Keyword 'AS'
|  |- 3 Whitespace ' '
|  `- 4 Identifier 'col1'
|     `- 0 Name 'col1'
|- 11 Whitespace ' '
|- 12 Keyword 'FROM'
|- 13 Whitespace ' '
`- 14 Identifier 't1'
   `- 0 Name 't1'
>>> p.tokens[10].get_alias()
'col1'