Remove unexpected check for column count in MergeUsing

h2/src/main/org/h2/command/dml/MergeUsing.java

@@ -397,11 +397,6 @@ public class MergeUsing extends Prepared {
                     }
                 }
             }
-        } else {
-            query.prepare();
-            if (query.getColumnCount() != columns.length) {
-                throw DbException.get(ErrorCode.COLUMN_COUNT_DOES_NOT_MATCH);
-            }
         }
 
         int embeddedStatementsCount = 0;

h2/src/test/org/h2/test/scripts/dml/mergeUsing.sql

@@ -72,3 +72,46 @@ DROP SCHEMA SOURCESCHEMA CASCADE;
 
 DROP SCHEMA DESTSCHEMA CASCADE;
 > ok
+
+CREATE TABLE SOURCE_TABLE(ID BIGINT PRIMARY KEY, C1 INT NOT NULL);
+> ok
+
+INSERT INTO SOURCE_TABLE VALUES (1, 10), (2, 20), (3, 30);
+> update count: 3
+
+CREATE TABLE DEST_TABLE(ID BIGINT PRIMARY KEY, C1 INT NOT NULL, C2 INT NOT NULL);
+> ok
+
+INSERT INTO DEST_TABLE VALUES (2, 200, 2000), (4, 400, 4000);
+> update count: 2
+
+MERGE INTO DEST_TABLE USING SOURCE_TABLE ON (DEST_TABLE.ID = SOURCE_TABLE.ID)
+    WHEN MATCHED THEN UPDATE SET DEST_TABLE.C1 = SOURCE_TABLE.C1, DEST_TABLE.C2 = 100;
+> update count: 1
+
+SELECT * FROM DEST_TABLE;
+> ID C1  C2
+> -- --- ----
+> 2  20  100
+> 4  400 4000
+> rows: 2
+
+MERGE INTO DEST_TABLE D USING SOURCE_TABLE S ON (D.ID = S.ID)
+    WHEN MATCHED THEN UPDATE SET D.C1 = S.C1, D.C2 = 100
+    WHEN NOT MATCHED THEN INSERT (ID, C1, C2) VALUES (S.ID, S.C1, 1000);
+> update count: 3
+
+SELECT * FROM DEST_TABLE;
+> ID C1  C2
+> -- --- ----
+> 1  10  1000
+> 2  20  100
+> 3  30  1000
+> 4  400 4000
+> rows: 4
+
+DROP TABLE SOURCE_TABLE;
+> ok
+
+DROP TABLE DEST_TABLE;
+> ok