duckdb · Mytherin · Jun 20, 2023 · Jun 14, 2023 · Jun 14, 2023 · Jun 16, 2023
diff --git a/src/include/duckdb/parser/transformer.hpp b/src/include/duckdb/parser/transformer.hpp
@@ -232,6 +232,9 @@ class Transformer {
 	unique_ptr<ParsedExpression> TransformParamRef(duckdb_libpgquery::PGParamRef &node);
 	unique_ptr<ParsedExpression> TransformNamedArg(duckdb_libpgquery::PGNamedArgExpr &root);
 
+	//! Transform multi assignment reference into an Expression
+	unique_ptr<ParsedExpression> TransformMultiAssignRef(duckdb_libpgquery::PGMultiAssignRef &root);
+
 	unique_ptr<ParsedExpression> TransformSQLValueFunction(duckdb_libpgquery::PGSQLValueFunction &node);
 
 	unique_ptr<ParsedExpression> TransformSubquery(duckdb_libpgquery::PGSubLink &root);

diff --git a/src/parser/transform/expression/CMakeLists.txt b/src/parser/transform/expression/CMakeLists.txt
@@ -18,7 +18,8 @@ add_library_unity(
   transform_operator.cpp
   transform_param_ref.cpp
   transform_positional_reference.cpp
-  transform_subquery.cpp)
+  transform_subquery.cpp
+  transform_multi_assign_reference.cpp)
 set(ALL_OBJECT_FILES
     ${ALL_OBJECT_FILES} $<TARGET_OBJECTS:duckdb_transformer_expression>
     PARENT_SCOPE)
diff --git a/src/parser/transform/expression/transform_expression.cpp b/src/parser/transform/expression/transform_expression.cpp
@@ -75,6 +75,8 @@ unique_ptr<ParsedExpression> Transformer::TransformExpression(duckdb_libpgquery:
 		return TransformStarExpression(PGCast<duckdb_libpgquery::PGAStar>(node));
 	case duckdb_libpgquery::T_PGBooleanTest:
 		return TransformBooleanTest(PGCast<duckdb_libpgquery::PGBooleanTest>(node));
+	case duckdb_libpgquery::T_PGMultiAssignRef:
+		return TransformMultiAssignRef(PGCast<duckdb_libpgquery::PGMultiAssignRef>(node));
 
 	default:
 		throw NotImplementedException("Expression type %s (%d)", NodetypeToString(node.type), (int)node.type);

diff --git a/src/parser/transform/expression/transform_multi_assign_reference.cpp b/src/parser/transform/expression/transform_multi_assign_reference.cpp
@@ -0,0 +1,44 @@
+#include "duckdb/parser/parsed_expression.hpp"
+#include "duckdb/parser/transformer.hpp"
+
+namespace duckdb {
+
+unique_ptr<ParsedExpression> Transformer::TransformMultiAssignRef(duckdb_libpgquery::PGMultiAssignRef &root) {
+	// Multi assignment for the ROW function
+	if (root.source->type == duckdb_libpgquery::T_PGFuncCall) {
+		auto func = PGCast<duckdb_libpgquery::PGFuncCall>(*root.source);
+
+		// Explicitly only allow ROW function
+		char const *function_name =
+		    PGPointerCast<duckdb_libpgquery::PGValue>(func.funcname->tail->data.ptr_value)->val.str;
+		if (function_name == nullptr || strlen(function_name) != 3 || strncmp(function_name, "row", 3) != 0) {
+			return TransformExpression(root.source);
+		}
+
+		// Too many columns (ie. (x, y) = (1, 2, 3) )
+		if (root.ncolumns < func.args->length) {
+			throw ParserException(
+			    "Could not perform multiple assignment, target only expects %d values, %d were provided", root.ncolumns,
+			    func.args->length);
+		}
+
+		// Get the expression corresponding with the current column
+		idx_t idx = 1;
+		auto list = func.args->head;
+		while (list && idx < static_cast<idx_t>(root.colno)) {
+			list = list->next;
+			++idx;
+		}
+
+		// Not enough columns (ie. (x, y, z) = (1, 2) )
+		if (!list) {
+			throw ParserException(
+			    "Could not perform multiple assignment, target expects %d values, only %d were provided", root.ncolumns,
+			    func.args->length);
+		}
+		return TransformExpression(reinterpret_cast<duckdb_libpgquery::PGNode *>(list->data.ptr_value));
+	}
+	return TransformExpression(root.source);
+}
+
+} // namespace duckdb
diff --git a/test/sql/update/test_multiple_assignment.test b/test/sql/update/test_multiple_assignment.test
@@ -0,0 +1,81 @@
+# name: test/sql/update/test_multiple_assignment.test
+# description: Update with multiple assignment
+# group: [update]
+
+#        create table and insert some values
+# ---------------------------------------------------
+statement ok
+CREATE TABLE tbl (key INT, fruit VARCHAR, cost INT);
+
+statement ok
+INSERT INTO tbl VALUES (1, 'apple', 2), (2, 'orange', 3);
+
+#                    simple case
+# ---------------------------------------------------
+statement ok
+UPDATE tbl SET (key, fruit, cost) = (1, 'pear', 2);
+
+query III
+SELECT * FROM tbl;
+----
+1	pear	2
+1	pear	2
+
+#                    ROW function
+# ---------------------------------------------------
+statement ok
+UPDATE tbl SET (key, fruit, cost) = (2, 'apple', 3);
+
+query III
+SELECT * FROM tbl;
+----
+2	apple	3
+2	apple	3
+
+#                      1 value
+# ---------------------------------------------------
+statement ok
+UPDATE tbl SET (key, fruit, cost) = 3;
+
+query III
+SELECT * FROM tbl;
+----
+3	3	3
+3	3	3
+
+#                   too few values
+# ---------------------------------------------------
+statement error
+UPDATE tbl SET (key, fruit, cost) = (1, 2);
+----
+Parser Error: Could not perform multiple assignment, target expects 3 values, only 2 were provided
+
+#                  too many values
+# ---------------------------------------------------
+statement error
+UPDATE tbl SET (key, fruit, cost) = (1, 2, 3, 4);
+----
+Parser Error: Could not perform multiple assignment, target only expects 3 values, 4 were provided
+
+#            functions should still work
+# ---------------------------------------------------
+statement ok
+UPDATE tbl SET (key, fruit, cost) = ADD(key, cost);
+
+query III
+SELECT * FROM tbl;
+----
+6	6	6
+6	6	6
+
+#                   empty lists
+# ---------------------------------------------------
+statement error
+UPDATE tbl SET () = (key, fruit);
+----
+Parser Error: syntax error at or near ")"
+
+statement error
+UPDATE tbl SET (key, fruit) = ();
+----
+Parser Error: syntax error at or near ")"