Serpiton questions

Serpiton answers

• Execute same query twice, but with single different WHERE clause
• Finding Median in sql server upto every date in the table
• Bring through previous 12 months count while grouping by period
• Select n amount of random rows where n is proportionate to each value's % of total population
• FIFO Implementation in Inventory using SQL
• Group consecutive rows of same value using time spans
• How can I sum up data in tree-like structure in SQL from children to parent?
• Seemingly simple SQL query turns out quite complex (Oracle)
• MySQL permutation