Please get me some advised...yuor help much be appreciated!!!
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Given the table structure and row data below, I have some questions in my mind, sorry Im just a beginner...
mysql> explain user_skill;
+--------------------------+------------------+------+-----+
| Field | Type | Null | Key |
+--------------------------+------------------+------+-----+
| user_skill_id | int(11) | | PRI |
| user_skill_last_modified | timestamp(14) | YES | |
| user_skill_date_created | datetime | YES | |
| user_id | int(11) | YES | |
| skill_name | char(255) | YES | |
| skill_level | char(255) | YES | |
| skill_usage | char(255) | YES | |
| skill_last_used | char(255) | YES | |
| user_skill_endorsed | tinyint(1) | YES | |
+--------------------------+------------------+------+-----+

mysql> *************
+--------------------+-------------------+--------------------+
| user_firstname | user_lastname | skill_name |
+--------------------+-------------------+--------------------+
| Kim | Simpson | PHP |
| Kim | Simpson | Perl |
| Kim | Simpson | Microsoft Word |
| Kim | Simpson | Microsoft Access |
| Kim | Simpson | Accounting/Billing |
| Kim | Simpson | Java |
| Kim | Simpson | SQL |
| Kim | Simpson | CSS |
| Kim | Simpson | OO Programming |
| Kim | Simpson | Microsoft Excel |
+--------------------+-------------------+--------------------+
10 rows in set (0.00 sec)

These are my questions:
1.Assuming that the data stored in skill_name in the user_skill table might be repeated for different users, what changes would I make to the database to normalize the skill_name and reduce repeated storage? what is the structure of the new table(s).

2.How could I Recreate the query that returned the 10 rows of data supplied. Speculate on tables that would be needed that are not shown here.

3. Given the following query, how could it be optimized? List all assumptions:

select c.* FROM companies AS c JOIN users AS u USING(companyid) JOIN jobs AS j USING(userid) JOIN useraccounts AS ua USING(userid) WHERE j.jobid = 123;