Want to find out the minimum or average on a given data? Learn to use SQLs aggregate function for this. http://www.sqltutorials.net/aggregate/how-to-use-sql-aggregate-functio...
Sometimes with outputted data, comes unwanted white space. The trim function is used for this in SQL. http://www.sqltutorials.net/concantenate/how-to-use-the-trim-function....
If you need to find the range in some data, then you need to use between as your operator. http://www.sqltutorials.net/comparison/sqls-between-range.html
Many times you will want to filter results for very specific terms. You can accomplish this by using having and group by operators. http://www.sqltutorials.net/comparison/filter-data-using-the-having-cl...