Add column_logical_type and get/set_alias methods

crates/duckdb/src/column.rs

@@ -2,7 +2,7 @@ use std::str;
 
 use arrow::datatypes::DataType;
 
-use crate::{Error, Result, Statement};
+use crate::{core::LogicalTypeHandle, Error, Result, Statement};
 
 /// Information about a column of a DuckDB query.
 #[derive(Debug)]
@@ -160,6 +160,11 @@ impl Statement<'_> {
     pub fn column_type(&self, idx: usize) -> DataType {
         self.stmt.column_type(idx)
     }
+
+    /// Returns the declared logical data type of the column.
+    pub fn column_logical_type(&self, idx: usize) -> LogicalTypeHandle {
+        self.stmt.column_logical_type(idx)
+    }
 }
 
 #[cfg(test)]

crates/duckdb/src/core/logical_type.rs

@@ -289,6 +289,28 @@ impl LogicalTypeHandle {
         };
         unsafe { Self::new(c_logical_type) }
     }
+
+    /// Alias of the logical type.
+    pub fn get_alias(&self) -> Option<String> {
+        unsafe {
+            let alias_ptr = duckdb_logical_type_get_alias(self.ptr);
+            if alias_ptr.is_null() {
+                None
+            } else {
+                let c_str = CString::from_raw(alias_ptr);
+                let alias = c_str.to_str().unwrap();
+                Some(alias.to_string())
+            }
+        }
+    }
+
+    /// Set the alias of the logical type.
+    pub fn set_alias(&self, alias: &str) {
+        unsafe {
+            let alias = CString::new(alias).unwrap();
+            duckdb_logical_type_set_alias(self.ptr, alias.as_ptr());
+        }
+    }
 }
 
 #[cfg(test)]

crates/duckdb/src/raw_statement.rs

@@ -9,7 +9,7 @@ use arrow::{
 use super::{ffi, Result};
 #[cfg(feature = "polars")]
 use crate::arrow2;
-use crate::{error::result_from_duckdb_arrow, Error};
+use crate::{core::LogicalTypeHandle, error::result_from_duckdb_arrow, Error};
 
 /// Private newtype for DuckDB prepared statements that finalize themselves when dropped.
 ///
@@ -215,6 +215,14 @@ impl RawStatement {
         self.schema().field(idx).data_type().to_owned()
     }
 
+    #[inline]
+    pub fn column_logical_type(&self, idx: usize) -> LogicalTypeHandle {
+        unsafe {
+            let ptr = ffi::duckdb_prepared_statement_column_logical_type(self.ptr, idx as u64);
+            LogicalTypeHandle::new(ptr)
+        }
+    }
+
     #[inline]
     pub fn schema(&self) -> SchemaRef {
         self.schema.clone().unwrap()