From 7b383cc537ef21485ba1d905bbd76134e377fbfe Mon Sep 17 00:00:00 2001
From: Alexey Kopytov <akopytov@gmail.com>
Date: Fri, 23 Mar 2018 19:13:52 +0300
Subject: [PATCH] Don't fail when query_row() is called with an empty SELECT.

---
 src/lua/internal/sysbench.sql.lua |  2 +-
 tests/include/api_sql_common.sh   | 15 ++++++++++++++-
 tests/t/api_sql_mysql.t           |  1 +
 tests/t/api_sql_pgsql.t           |  1 +
 4 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/src/lua/internal/sysbench.sql.lua b/src/lua/internal/sysbench.sql.lua
index 6e5f226..6f33d33 100644
--- a/src/lua/internal/sysbench.sql.lua
+++ b/src/lua/internal/sysbench.sql.lua
@@ -299,7 +299,7 @@ end
 function connection_methods.query_row(self, query)
    local rs = self:query(query)
 
-   if rs == nil then
+   if rs == nil or rs.nrows == 0 then
       return nil
    end
 
diff --git a/tests/include/api_sql_common.sh b/tests/include/api_sql_common.sh
index 6582728..6b31546 100644
--- a/tests/include/api_sql_common.sh
+++ b/tests/include/api_sql_common.sh
@@ -210,13 +210,26 @@ sysbench $SB_ARGS run
 ########################################################################
 cat >$CRAMTMP/api_sql.lua <<EOF
 c = sysbench.sql.driver():connect()
-c:query("CREATE TABLE IF NOT EXISTS t1(a INT)")
+c:query("CREATE TABLE t1(a INT)")
 c:bulk_insert_init("INSERT INTO t1 VALUES")
 c:bulk_insert_next("(1)")
 c:bulk_insert_done()
 e,m = pcall(function () c:bulk_insert_next("(2)") end)
 print(m)
 c:bulk_insert_done()
+c:query("DROP TABLE t1")
+EOF
+
+sysbench $SB_ARGS
+
+########################################################################
+# query_row() with an empty result set
+########################################################################
+cat >$CRAMTMP/api_sql.lua <<EOF
+c = sysbench.sql.driver():connect()
+c:query("CREATE TABLE t1(a INT)")
+print(c:query_row("SELECT * FROM t1"))
+c:query("DROP TABLE t1")
 EOF
 
 sysbench $SB_ARGS
diff --git a/tests/t/api_sql_mysql.t b/tests/t/api_sql_mysql.t
index c1eb6a1..20c6e2f 100644
--- a/tests/t/api_sql_mysql.t
+++ b/tests/t/api_sql_mysql.t
@@ -114,3 +114,4 @@ SQL Lua API + MySQL tests
   10
   ALERT: attempt to call bulk_insert_next() before bulk_insert_init()
   */api_sql.lua:*: db_bulk_insert_next() failed (glob)
+  nil
diff --git a/tests/t/api_sql_pgsql.t b/tests/t/api_sql_pgsql.t
index 3098fa3..64bc820 100644
--- a/tests/t/api_sql_pgsql.t
+++ b/tests/t/api_sql_pgsql.t
@@ -120,3 +120,4 @@ SQL Lua API + PostgreSQL tests
   10
   ALERT: attempt to call bulk_insert_next() before bulk_insert_init()
   */api_sql.lua:*: db_bulk_insert_next() failed (glob)
+  nil