Added: arguments merge feature.

sqlx-core/src/any/arguments.rs

@@ -30,6 +30,10 @@ impl Arguments for AnyArguments {
     fn len(&self) -> usize {
         self.values.0.len()
     }
+
+    fn merge(&mut self, arguments: Self) {
+        self.values.0.extend(arguments.values.0);
+    }
 }
 
 #[derive(Default)]

sqlx-core/src/arguments.rs

@@ -27,6 +27,8 @@ pub trait Arguments: Send + Sized + Default {
     fn format_placeholder<W: Write>(&self, writer: &mut W) -> fmt::Result {
         writer.write_str("?")
     }
+
+    fn merge(&mut self, arguments: Self);
 }
 
 pub trait IntoArguments<DB: Database>: Sized + Send {

sqlx-mysql/src/arguments.rs

@@ -55,6 +55,20 @@ impl Arguments for MySqlArguments {
     fn len(&self) -> usize {
         self.types.len()
     }
+
+    fn merge(&mut self, arguments: Self) {
+        self.values.extend(arguments.values);
+        self.types.extend(arguments.types);
+
+        for i in 0..arguments.null_bitmap.length {
+            let byte_index = i / 8;
+            let bit_offset = i % 8;
+            let is_null = (arguments.null_bitmap.bytes[byte_index] & (1 << bit_offset)) != 0;
+
+            self.null_bitmap
+                .push(if is_null { IsNull::Yes } else { IsNull::No });
+        }
+    }
 }
 
 #[derive(Debug, Default, Clone)]

sqlx-postgres/src/arguments.rs

@@ -161,6 +161,25 @@ impl Arguments for PgArguments {
     fn len(&self) -> usize {
         self.buffer.count
     }
+
+    fn merge(&mut self, arguments: Self) {
+        let buf_offset = self.buffer.len();
+        let count_offset = self.buffer.count;
+
+        self.types.extend(arguments.types);
+        self.buffer.count += arguments.buffer.count;
+        self.buffer.buffer.extend(arguments.buffer.buffer);
+
+        for mut patch in arguments.buffer.patches {
+            patch.buf_offset += buf_offset;
+            patch.arg_index += count_offset;
+            self.buffer.patches.push(patch);
+        }
+
+        for (offset, kind) in arguments.buffer.type_holes {
+            self.buffer.type_holes.push((offset + buf_offset, kind));
+        }
+    }
 }
 
 impl PgArgumentBuffer {

sqlx-sqlite/src/arguments.rs

@@ -66,6 +66,10 @@ impl Arguments for SqliteArguments {
     fn len(&self) -> usize {
         self.values.0.len()
     }
+
+    fn merge(&mut self, arguments: Self) {
+        self.values.0.extend(arguments.values.0);
+    }
 }
 
 impl SqliteArguments {