1 files changed, 29 insertions, 23 deletions

diff --git a/tool/sqldiff.c b/tool/sqldiff.c
index 1102a89fc..f5edd6014 100644
--- a/tool/sqldiff.c
+++ b/tool/sqldiff.c
@@ -789,8 +789,10 @@ static void getRbudiffQuery(
   /* Deleted rows: */
   strPrintf(pSql, "\nUNION ALL\nSELECT ");
   strPrintfArray(pSql, ", ", "%s", azCol, nPK);
-  strPrintf(pSql, ", ");
-  strPrintfArray(pSql, ", ", "NULL", &azCol[nPK], -1);
+  if( azCol[nPK] ){
+    strPrintf(pSql, ", ");
+    strPrintfArray(pSql, ", ", "NULL", &azCol[nPK], -1);
+  }
   strPrintf(pSql, ", 1");         /* Set ota_control to 1 for a delete */
   strPrintf(pSql, " FROM main.%Q AS n WHERE NOT EXISTS (\n", zTab);
   strPrintf(pSql, "    SELECT 1 FROM ", zTab);
@@ -798,29 +800,33 @@ static void getRbudiffQuery(
   strPrintfArray(pSql, " AND ", "(n.%Q IS o.%Q)", azCol, nPK);
   strPrintf(pSql, "\n) ");
 
-  /* Updated rows: */
-  strPrintf(pSql, "\nUNION ALL\nSELECT ");
-  strPrintfArray(pSql, ", ", "n.%s", azCol, nPK);
-  strPrintf(pSql, ",\n");
-  strPrintfArray(pSql, " ,\n", 
-      "    CASE WHEN n.%s IS o.%s THEN NULL ELSE n.%s END", &azCol[nPK], -1
-  );
-
-  if( bOtaRowid==0 ){
-    strPrintf(pSql, ", '");
-    strPrintfArray(pSql, "", ".", azCol, nPK);
-    strPrintf(pSql, "' ||\n");
-  }else{
+  /* Updated rows. If all table columns are part of the primary key, there 
+  ** can be no updates. In this case this part of the compound SELECT can
+  ** be omitted altogether. */
+  if( azCol[nPK] ){
+    strPrintf(pSql, "\nUNION ALL\nSELECT ");
+    strPrintfArray(pSql, ", ", "n.%s", azCol, nPK);
     strPrintf(pSql, ",\n");
-  }
-  strPrintfArray(pSql, " ||\n", 
-      "    CASE WHEN n.%s IS o.%s THEN '.' ELSE 'x' END", &azCol[nPK], -1
-  );
-  strPrintf(pSql, "\nAS ota_control");
+    strPrintfArray(pSql, " ,\n", 
+        "    CASE WHEN n.%s IS o.%s THEN NULL ELSE n.%s END", &azCol[nPK], -1
+    );
 
-  strPrintf(pSql, "\nFROM main.%Q AS o, aux.%Q AS n\nWHERE ", zTab, zTab);
-  strPrintfArray(pSql, " AND ", "(n.%Q IS o.%Q)", azCol, nPK);
-  strPrintf(pSql, " AND ota_control LIKE '%%x%%'");
+    if( bOtaRowid==0 ){
+      strPrintf(pSql, ", '");
+      strPrintfArray(pSql, "", ".", azCol, nPK);
+      strPrintf(pSql, "' ||\n");
+    }else{
+      strPrintf(pSql, ",\n");
+    }
+    strPrintfArray(pSql, " ||\n", 
+        "    CASE WHEN n.%s IS o.%s THEN '.' ELSE 'x' END", &azCol[nPK], -1
+    );
+    strPrintf(pSql, "\nAS ota_control");
+
+    strPrintf(pSql, "\nFROM main.%Q AS o, aux.%Q AS n\nWHERE ", zTab, zTab);
+    strPrintfArray(pSql, " AND ", "(n.%Q IS o.%Q)", azCol, nPK);
+    strPrintf(pSql, " AND ota_control LIKE '%%x%%'");
+  }
 
   /* Now add an ORDER BY clause to sort everything by PK. */
   strPrintf(pSql, "\nORDER BY ");