[libgda] Fix memory leak at GdaSqlProvider render operation

[Daniel Espinosa Ortiz <despinosa src gnome org>]

commit c0c594158e09ff8a73e80aa2ca27e5022b0516dd
Author: Daniel Espinosa <esodan gmail com>
Date:   Sun Apr 14 20:40:18 2019 -0500

    Fix memory leak at GdaSqlProvider render operation

 libgda/sqlite/gda-sqlite-provider.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/libgda/sqlite/gda-sqlite-provider.c b/libgda/sqlite/gda-sqlite-provider.c
index 07c80efc4..12d57e7e7 100644
--- a/libgda/sqlite/gda-sqlite-provider.c
+++ b/libgda/sqlite/gda-sqlite-provider.c
@@ -2386,7 +2386,6 @@ sqlite_render_operation (GdaSqlOperation *op, GdaSqlRenderingContext *context, G
        sql_list = g_slist_reverse (sql_list);
 
        str = NULL;
-       string = g_string_new ("");
        switch (op->operator_type) {
        case GDA_SQL_OPERATOR_TYPE_EQ:
                if (SQL_OPERAND (sql_list->next->data)->is_null)
@@ -2480,7 +2479,7 @@ sqlite_render_operation (GdaSqlOperation *op, GdaSqlRenderingContext *context, G
                if (sql_list->next && !(sql_list->next->next) &&
                    *(SQL_OPERAND (sql_list->next->data)->sql)=='(')
                        add_p = FALSE;
-
+         string = g_string_new ("");
                string = g_string_append (string, SQL_OPERAND (sql_list->data)->sql);
                if (op->operator_type == GDA_SQL_OPERATOR_TYPE_IN)
                        g_string_append (string, " IN ");
@@ -2497,6 +2496,7 @@ sqlite_render_operation (GdaSqlOperation *op, GdaSqlRenderingContext *context, G
                        g_string_append_c (string, ')');
                str = string->str;
                g_string_free (string, FALSE);
+    string = NULL;
                break;
        }
        case GDA_SQL_OPERATOR_TYPE_CONCAT: