Hey.
You want to insert the data form 50-200 form input fields into a single field in a MySQL table?!
You never put more than a single piece of data into a single field. It's the first, and most important, rule of database design.
If you need to store 50-200 pieces of personal info on your users, you either create a single table that has 200 columns, one for each possible piece of data (not every field has to be filled for each row), or you create a "dynamic" table, where you just store a key/value pair, filling in each as you go.
Example of the first option: (very basic)
- +----+-----------+-----------+----------+---------------+--------+
-
| id | ss_number | firstname | lastname | favorit_color | etc... |
-
+----+-----------+-----------+----------+---------------+--------+
-
| 1 | 11111111 | John | Doe | Blue | ... |
-
| 2 | NULL | Jane | Doe | Red | ... |
-
+----+-----------+-----------+----------+---------------+--------+
(Note the NULL for the second row's ss_number field. Indicates that there was no value provided for that field.)
Example of the second option:
- +----+-----------+----------+
-
| id | firstname | lastname |
-
+----+-----------+----------+
-
| 1 | John | Doe |
-
| 2 | Jane | Doe |
-
+----+-----------+----------+
-
+----+---------+---------------+-----------+
-
| id | user_id | key | value |
-
+----+---------+---------------+-----------+
-
| 1 | 1 | favorit_color | Blue |
-
| 2 | 1 | ss_number | 11111111 |
-
| 3 | 2 | favorit_color | Red |
-
+----+---------+---------------+-----------+
(Here, the absence of the second user's ss_number just means that it is not inserted into the key/value table.) 
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