Fix static-validation to use correct database placeholders

- Add static_placeholder() function that uses $1 for postgres, ? for mysql/sqlite
- Restore static-validation feature with proper database-specific SQL
- cfg!(feature = "static-validation") now works correctly with query_as! macro

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Cargo.toml

@@ -5,7 +5,7 @@ edition.workspace = true
 description = "Entity CRUD and change tracking for SQL databases with SQLx"
 
 [workspace.package]
-version = "0.3.3"
+version = "0.3.4"
 edition = "2021"
 
 [dependencies]
@@ -28,6 +28,7 @@ members = [
 [features]
 default = []
 derive = ["dep:sqlx-record-derive"]
+static-validation = ["sqlx-record-derive?/static-validation"]
 decimal = ["dep:rust_decimal", "sqlx/rust_decimal"]
 
 # Database backends - user must enable at least one

sqlx-record-derive/Cargo.toml

@@ -13,6 +13,7 @@ futures = "0.3"
 
 [features]
 default = []
+static-validation = []
 mysql = []
 postgres = []
 sqlite = []

sqlx-record-derive/src/lib.rs

@@ -106,6 +106,14 @@ fn table_quote() -> &'static str {
     { "`" }
 }
 
+/// Get compile-time placeholder for static-validation SQL
+fn static_placeholder(index: usize) -> String {
+    #[cfg(feature = "postgres")]
+    { format!("${}", index) }
+    #[cfg(not(feature = "postgres"))]
+    { let _ = index; "?".to_string() }
+}
+
 fn derive_entity_internal(input: TokenStream) -> TokenStream {
     let input = parse_macro_input!(input as DeriveInput);
     let name = &input.ident;
@@ -565,7 +573,51 @@ fn generate_get_impl(
 
     let field_list = fields.iter().map(|f| f.db_name.clone()).collect::<Vec<_>>();
 
-    let get_by_impl = quote! {
+    // Check if static-validation feature is enabled at macro expansion time
+    let use_static_validation = cfg!(feature = "static-validation");
+
+    let get_by_impl = if use_static_validation {
+        // Static validation: use sqlx::query_as! with compile-time checked SQL
+        let select_stmt = format!(
+            r#"SELECT DISTINCT {} FROM {}{}{} WHERE {} = {}"#,
+            select_fields.clone().collect::<Vec<_>>().join(", "),
+            tq, table_name, tq, pk_db_field_name,
+            static_placeholder(1)
+        );
+        quote! {
+            pub async fn #get_by_func<'a, E>(executor: E, #pk_field: &#pk_type) -> Result<Option<Self>, sqlx::Error>
+            where
+                E: sqlx::Executor<'a, Database=#db>,
+            {
+                let result = sqlx::query_as!(
+                    Self,
+                    #select_stmt,
+                    #pk_field
+                )
+                .fetch_optional(executor)
+                .await?;
+
+                Ok(result)
+            }
+
+            pub async fn get_by_primary_key<'a, E>(executor: E, #pk_field: &#pk_type) -> Result<Option<Self>, sqlx::Error>
+            where
+                E: sqlx::Executor<'a, Database=#db>,
+            {
+                let result = sqlx::query_as!(
+                    Self,
+                    #select_stmt,
+                    #pk_field
+                )
+                .fetch_optional(executor)
+                .await?;
+
+                Ok(result)
+            }
+        }
+    } else {
+        // Runtime: use sqlx::query_as with dynamic SQL
+        quote! {
             pub async fn #get_by_func<'a, E>(executor: E, #pk_field: &#pk_type) -> Result<Option<Self>, sqlx::Error>
             where
                 E: sqlx::Executor<'a, Database=#db>,
@@ -601,6 +653,7 @@ fn generate_get_impl(
 
                 Ok(result)
             }
+        }
     };
 
     quote! {