Fahmi questions

Fahmi answers

• First 5 rows summed per ref per type, all others equal 1, grouped by a team ID
• LEFT OUTER JOIN with WHERE clause on 2nd table, not effecting 1st table
• Min() and Max() based on partition in sql server
• PostgreSQL removing duplicates without id or unique_key [duplicate]
• SUM value group by columns but do not 'aggregate' possible?
• Select users having required roles only
• How to merge multiple rows into one row with filtering rules in SQL Server
• How to get the Count of a column which has different values in it
• Join table and pick rows where for given id exists only one value
• MySQL extract gender as a string when it stored in the table as a Boolean