I've tried to set this by using SET VARIABLE but it said that have_query_cache is read-only
mysql>SHOW VARIABLES LIKE 'have_query_cache';
+------------------+-------+
| Variable_name | Value |
+------------------+-------+
| have_query_cache | YES |
+------------------+-------+
For supported versions of MySQL (less than 8.0 or so), you enable the query cache in the server configuration using e.g. the variables query_cache_size
and query_cache_type
.
The have_query_cache
variable only informs you whether the cache is enabled at present.