fix: Consider column names' case when aliasing tables (#22917)

## Which issue does this PR close?

- Closes #22916.

## Rationale for this change

Avoid errors when aliasing tables/subqueries with case sensitive column
names.

## What changes are included in this PR?

- Update `apply_expr_alias` so it aliases the original columns directly.

## Are these changes tested?

Yes.

## Are there any user-facing changes?

No.

Author: nuno-faria

datafusion/sql/src/planner.rs

@@ -32,10 +32,10 @@ use datafusion_common::{
     DFSchemaRef, Diagnostic, SchemaError, field_not_found, internal_err,
     plan_datafusion_err,
 };
+use datafusion_expr::Expr;
 use datafusion_expr::logical_plan::{LogicalPlan, LogicalPlanBuilder};
 pub use datafusion_expr::planner::ContextProvider;
 use datafusion_expr::utils::find_column_exprs;
-use datafusion_expr::{Expr, col};
 use sqlparser::ast::{ArrayElemTypeDef, ExactNumberInfo, TimezoneInfo};
 use sqlparser::ast::{ColumnDef as SQLColumnDef, ColumnOption};
 use sqlparser::ast::{DataType as SQLDataType, Ident, ObjectName, TableAlias};
@@ -591,10 +591,10 @@ impl<'a, S: ContextProvider> SqlToRel<'a, S> {
                 idents.len()
             )
         } else {
-            let fields = plan.schema().fields().clone();
+            let columns = plan.schema().columns().clone();
             LogicalPlanBuilder::from(plan)
-                .project(fields.iter().zip(idents).map(|(field, ident)| {
-                    col(field.name()).alias(self.ident_normalizer.normalize(ident))
+                .project(columns.into_iter().zip(idents).map(|(col, ident)| {
+                    Expr::Column(col).alias(self.ident_normalizer.normalize(ident))
                 }))?
                 .build()
         }

datafusion/sqllogictest/test_files/alias.slt

@@ -57,3 +57,50 @@ drop table t1;
 
 statement count 0
 drop table t2;
+
+
+# Test table-aliasing a subquery with case sensitive columns
+# (https://github.com/apache/datafusion/issues/22916)
+
+statement ok
+create table t ("A" int, "B.C" int);
+
+query II
+select * from (select * from t) t_(x, y);
+----
+
+query TT
+explain select * from (select * from t) t_(x, y);
+----
+logical_plan
+01)SubqueryAlias: t_
+02)--Projection: t.A AS x, t.B.C AS y
+03)----TableScan: t projection=[A, B.C]
+physical_plan
+01)ProjectionExec: expr=[A@0 as x, B.C@1 as y]
+02)--DataSourceExec: partitions=1, partition_sizes=[0]
+
+query TT
+explain select * from (select * from t) t_(X, Y);
+----
+logical_plan
+01)SubqueryAlias: t_
+02)--Projection: t.A AS x, t.B.C AS y
+03)----TableScan: t projection=[A, B.C]
+physical_plan
+01)ProjectionExec: expr=[A@0 as x, B.C@1 as y]
+02)--DataSourceExec: partitions=1, partition_sizes=[0]
+
+query TT
+explain select * from (select * from t) t_("X", "Y");
+----
+logical_plan
+01)SubqueryAlias: t_
+02)--Projection: t.A AS X, t.B.C AS Y
+03)----TableScan: t projection=[A, B.C]
+physical_plan
+01)ProjectionExec: expr=[A@0 as X, B.C@1 as Y]
+02)--DataSourceExec: partitions=1, partition_sizes=[0]
+
+statement ok
+drop table t;