Never set negative learn counts

Issue: #496

diff --git a/src/libstat/backends/sqlite3_backend.c b/src/libstat/backends/sqlite3_backend.c
index 7f57636e442f0068e8b21c758a91c5d1fefb70a6..bead2cecb08dd965813b0a002cfd41da8b43438a 100644 (file)
--- a/src/libstat/backends/sqlite3_backend.c
+++ b/src/libstat/backends/sqlite3_backend.c
@@ -190,8 +190,8 @@ static struct rspamd_sqlite3_prstmt prepared_stmts[RSPAMD_STAT_BACKEND_MAX] =
        },
        [RSPAMD_STAT_BACKEND_DEC_LEARNS] = {
                .idx = RSPAMD_STAT_BACKEND_DEC_LEARNS,
-               .sql = "UPDATE languages SET learns=learns - 1 WHERE id=?1;"
-                               "UPDATE users SET learns=learns - 1 WHERE id=?2;",
+               .sql = "UPDATE languages SET learns=MAX(0, learns - 1) WHERE id=?1;"
+                               "UPDATE users SET learns=MAX(0, learns - 1) WHERE id=?2;",
                .stmt = NULL,
                .args = "II",
                .result = SQLITE_DONE,
@@ -200,7 +200,7 @@ static struct rspamd_sqlite3_prstmt prepared_stmts[RSPAMD_STAT_BACKEND_MAX] =
        },
        [RSPAMD_STAT_BACKEND_GET_LEARNS] = {
                .idx = RSPAMD_STAT_BACKEND_GET_LEARNS,
-               .sql = "SELECT sum(learns) FROM languages;",
+               .sql = "SELECT SUM(MAX(0, learns)) FROM languages;",
                .stmt = NULL,
                .args = "",
                .result = SQLITE_ROW,