Retrieve from MySQL only if it contains two hyphen symbols?

For this, use the LIKE operator. Let us first create a table:

mysql> create table DemoTable
   (
   Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,
   Password varchar(100)
   );
Query OK, 0 rows affected (1.27 sec)

Insert some records in the table using insert command −

mysql> insert into DemoTable(Password) values('John@--123');
Query OK, 1 row affected (0.19 sec)
mysql> insert into DemoTable(Password) values('---Carol234');
Query OK, 1 row affected (0.20 sec)
mysql> insert into DemoTable(Password) values('--David987');
Query OK, 1 row affected (0.13 sec)
mysql> insert into DemoTable(Password) values('Mike----53443');
Query OK, 1 row affected (0.30 sec)

Display all records from the table using select statement:

mysql> select *from DemoTable;

Output

+----+---------------+
| Id | Password      |
+----+---------------+
| 1  | John@--123    |
| 2  | ---Carol234   |
| 3  | --David987    |
| 4  | Mike----53443 |
+----+---------------+
4 rows in set (0.00 sec)

Following is the query to retrieve from MySQL if it only contains two hyphen symbols -

mysql> select *from DemoTable where Password like '%--%' and password not like '%---%';

Output

+----+------------+
| Id | Password   |
+----+------------+
| 1  | John@--123 |
| 3  | --David987 |
+----+------------+
2 rows in set (0.06 sec)