How to create branches in MySQL: BEGIN, IF THEN?

Question

MySQL

MySQL gives an error in condition statements, but I do everything according to the reference book.

BEGIN;
    SET @lines := 0;
    SELECT count(*) FROM `prod_attr ` INTO @lines ;
      IF @lines > 4000        THEN       -- Тут ошибка  
            SELECT "MAX";
            TRUNCATE TABLE  `prod_attr ` ;
      END IF;
END;

Answer 1

only inside the begin ... end block
BEGIN ... END syntax is used for writing compound statements, which can appear within stored programs (stored procedures and functions, triggers, and events
in this particular case, BEGIN is interpreted as an alias START TRANSACTION; , and IF - as a function