When I create a key or index, the value shown in the key field is MUL.
What does MUL mean? Is there any way to determine if the field is a key
or index?
I created a test table with:
mysql> create table key_test (key1 char(10) not null, key2 char(5) not null, index1 int
> not null, field4 char(12) not null, primary key (key1), key (key2), index (index1), unique
> (field4));
Query OK, 0 rows affected (0.01 sec)
So then I have this table:
mysql> describe key_test;
+--------+----------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+--------+----------+------+-----+---------+-------+
| key1 | char(10) | | PRI | | |
| key2 | char(5) | | MUL | | |
| index1 | int(11) | | MUL | 0 | |
| field4 | char(12) | | UNI | | |
+--------+----------+------+-----+---------+-------+
I tried a show index:
mysql> show index from key_test;
+----------+------------+----------+--------------+-------------+-----------+-------------+----------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality
| Sub_part |
+----------+------------+----------+--------------+-------------+-----------+-------------+----------+
| key_test | 0 | PRIMARY | 1 | key1 | A | 0
| NULL |
| key_test | 1 | key2 | 1 | key2 | A | NULL
| NULL |
| key_test | 1 | index1 | 1 | index1 | A | NULL
| NULL |
| key_test | 0 | field4 | 1 | field4 | A | 0
| NULL |
+----------+------------+----------+--------------+-------------+-----------+-------------+----------+
4 rows in set (0.00 sec)
But it still isn't clear to me how I know key2 is a KEY and index1 is an INDEX?
Thanks for your help,
Anna Winkler
