Keywords are parsed as functions in select statements

# Abstract
Qualified names like of the form `.` are sometimes parsed as functions, like in:

```sql
SELECT t.user FROM t;
```

# Current Behavior
This is done with `cargo run --example cli -- test.sql --generic`:

```sql
select t.user from t;
```

results in:

```text
[
Query(
Query {
with: None,
body: Select(
Select {
select_token: TokenWithSpan {
token: Word(
Word {
value: "select",
quote_style: None,
keyword: SELECT,
},
),
span: Span(Location(1,1)..Location(1,7)),
},
distinct: None,
top: None,
top_before_distinct: false,
projection: [
UnnamedExpr(
Function(
Function {
name: ObjectName(
[
Identifier(
Ident {
value: "t",
quote_style: None,
span: Span(Location(1,8)..Location(1,9)),
},
),
Identifier(
Ident {
value: "user",
quote_style: None,
span: Span(Location(1,10)..Location(1,14)),
},
),
],
),
uses_odbc_syntax: false,
parameters: None,
args: None,
filter: None,
null_treatment: None,
over: None,
within_group: [],
},
),
),
],
into: None,
from: [
TableWithJoins {
relation: Table {
name: ObjectName(
[
Identifier(
Ident {
value: "t",
quote_style: None,
span: Span(Location(1,20)..Location(1,21)),
},
),
],
),
alias: None,
args: None,
with_hints: [],
version: None,
with_ordinality: false,
partitions: [],
json_path: None,
sample: None,
index_hints: [],
},
joins: [],
},
],
lateral_views: [],
prewhere: None,
selection: None,
group_by: Expressions(
[],
[],
),
cluster_by: [],
distribute_by: [],
sort_by: [],
having: None,
named_window: [],
qualify: None,
window_before_qualify: false,
value_table_mode: None,
connect_by: None,
flavor: Standard,
},
),
order_by: None,
limit_clause: None,
fetch: None,
locks: [],
for_clause: None,
settings: None,
format_clause: None,
pipe_operators: [],
},
),
]
```

and `cargo run --example cli -- test.sql --postgres` is the same:

```text
[
Query(
Query {
with: None,
body: Select(
Select {
select_token: TokenWithSpan {
token: Word(
Word {
value: "select",
quote_style: None,
keyword: SELECT,
},
),
span: Span(Location(1,1)..Location(1,7)),
},
distinct: None,
top: None,
top_before_distinct: false,
projection: [
UnnamedExpr(
Function(
Function {
name: ObjectName(
[
Identifier(
Ident {
value: "t",
quote_style: None,
span: Span(Location(1,8)..Location(1,9)),
},
),
Identifier(
Ident {
value: "user",
quote_style: None,
span: Span(Location(1,10)..Location(1,14)),
},
),
],
),
uses_odbc_syntax: false,
parameters: None,
args: None,
filter: None,
null_treatment: None,
over: None,
within_group: [],
},
),
),
],
into: None,
from: [
TableWithJoins {
relation: Table {
name: ObjectName(
[
Identifier(
Ident {
value: "t",
quote_style: None,
span: Span(Location(1,20)..Location(1,21)),
},
),
],
),
alias: None,
args: None,
with_hints: [],
version: None,
with_ordinality: false,
partitions: [],
json_path: None,
sample: None,
index_hints: [],
},
joins: [],
},
],
lateral_views: [],
prewhere: None,
selection: None,
group_by: Expressions(
[],
[],
),
cluster_by: [],
distribute_by: [],
sort_by: [],
having: None,
named_window: [],
qualify: None,
window_before_qualify: false,
value_table_mode: None,
connect_by: None,
flavor: Standard,
},
),
order_by: None,
limit_clause: None,
fetch: None,
locks: [],
for_clause: None,
settings: None,
format_clause: None,
pipe_operators: [],
},
),
]
```

# Expected Behavior
I think this should parse similar to

```sql
select t.foo from t;
```

with `cargo run --example cli -- test.sql --generic`:

```text
[
Query(
Query {
with: None,
body: Select(
Select {
select_token: TokenWithSpan {
token: Word(
Word {
value: "select",
quote_style: None,
keyword: SELECT,
},
),
span: Span(Location(1,1)..Location(1,7)),
},
distinct: None,
top: None,
top_before_distinct: false,
projection: [
UnnamedExpr(
CompoundIdentifier(
[
Ident {
value: "t",
quote_style: None,
span: Span(Location(1,8)..Location(1,9)),
},
Ident {
value: "foo",
quote_style: None,
span: Span(Location(1,10)..Location(1,13)),
},
],
),
),
],
into: None,
from: [
TableWithJoins {
relation: Table {
name: ObjectName(
[
Identifier(
Ident {
value: "t",
quote_style: None,
span: Span(Location(1,19)..Location(1,20)),
},
),
],
),
alias: None,
args: None,
with_hints: [],
version: None,
with_ordinality: false,
partitions: [],
json_path: None,
sample: None,
index_hints: [],
},
joins: [],
},
],
lateral_views: [],
prewhere: None,
selection: None,
group_by: Expressions(
[],
[],
),
cluster_by: [],
distribute_by: [],
sort_by: [],
having: None,
named_window: [],
qualify: None,
window_before_qualify: false,
value_table_mode: None,
connect_by: None,
flavor: Standard,
},
),
order_by: None,
limit_clause: None,
fetch: None,
locks: [],
for_clause: None,
settings: None,
format_clause: None,
pipe_operators: [],
},
),
]
```

# Others
Also see PostgreSQL:

```text
psql (17.5 (Debian 17.5-1.pgdg120+1))
Type "help" for help.

postgres=# create table t(a int, "user" text);
CREATE TABLE
postgres=# insert into t values (1, 'foo');
INSERT 0 1
postgres=# select t.user from t;
user
------
foo
(1 row)
```

Interestingly, even the plain `user` works:

```text
postgres=# select user from t;
user
----------
postgres
(1 row)
```

# References
- a potentially valid case of treating `user` as a function: #1658
- downstream: https://github.com/apache/datafusion/issues/14141

Tái hiện vấn đề bằng lệnh cargo run --example cli đã đề cập, sử dụng test.sql cùng với cả --generic và --postgres. Theo dõi quá trình phân tích cú pháp biểu thức SQL phân loại t.user là Function thay vì CompoundIdentifier được minh họa cho t.foo, sau đó bổ sung coverage cho truy vấn bị lỗi và xác minh rằng cả hai dialect đều tạo ra dạng parse như mong đợi.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.