MDEV-10411 Providing compatibility for basic PL/SQL constructs

An additional change for "Part 9: EXCEPTION handlers"

This construct:
  EXCEPTION WHEN OTHERS THEN ...;
now catches warning-alike conditions, e.g. NO_DATA_FOUND.

mysql-test/suite/compat/oracle/r/exception.result

@@ -199,5 +199,24 @@ ERROR 24000: Cursor is not open
 DROP PROCEDURE p1;
 DROP TABLE t1;
 #
+# Testing that warning-alike errors are caught by OTHERS
+#
+CREATE TABLE t1 (a INT);
+CREATE FUNCTION f1 RETURN VARCHAR
+AS
+a INT:=10;
+BEGIN
+SELECT a INTO a FROM t1;
+RETURN 'OK';
+EXCEPTION
+WHEN OTHERS THEN RETURN 'Exception';
+END;
+$$
+SELECT f1() FROM DUAL;
+f1()
+Exception
+DROP FUNCTION f1;
+DROP TABLE t1;
+#
 # End of MDEV-10840 sql_mode=ORACLE: RAISE statement for predefined exceptions
 #

mysql-test/suite/compat/oracle/t/exception.test

@@ -239,6 +239,27 @@ CALL p1();
 DROP PROCEDURE p1;
 DROP TABLE t1;
 
+--echo #
+--echo # Testing that warning-alike errors are caught by OTHERS
+--echo #
+
+CREATE TABLE t1 (a INT);
+DELIMITER $$;
+CREATE FUNCTION f1 RETURN VARCHAR
+AS
+  a INT:=10;
+BEGIN
+  SELECT a INTO a FROM t1;
+  RETURN 'OK';
+EXCEPTION
+  WHEN OTHERS THEN RETURN 'Exception';
+END;
+$$
+DELIMITER ;$$
+SELECT f1() FROM DUAL;
+DROP FUNCTION f1;
+DROP TABLE t1;
+
 
 --echo #
 --echo # End of MDEV-10840 sql_mode=ORACLE: RAISE statement for predefined exceptions

sql/sp_pcontext.cc

@@ -410,8 +410,16 @@ sp_pcontext::find_handler(const char *sql_state,
         break;
 
       case sp_condition_value::EXCEPTION:
-        if (is_sqlstate_exception(sql_state) &&
+        /*
-            level == Sql_condition::WARN_LEVEL_ERROR && !found_cv)
+          In sql_mode=ORACLE this construct should catch errors and warnings:
+            EXCEPTION
+              WHEN OTHERS THEN ...;
+          E.g. NO_DATA_FOUND is more like a warning than an error,
+          and it should be caught.
+        */
+        if (((current_thd->variables.sql_mode & MODE_ORACLE) ||
+             (is_sqlstate_exception(sql_state) &&
+              level == Sql_condition::WARN_LEVEL_ERROR)) && !found_cv)
         {
           found_cv= cv;
           found_handler= h;