Lab Sql

I am looking to identify return visitors to a website within a 7 day window. A data sample and atte… Read more Postgresql: Identifying Return Visitors Based On Date - Joins Or Window Functions?

My table has values like (RowCount is generated by the query below): ID Date_trans Time_tra… Read more Row_number() Shows Unexpected Values

I have a weird requirement which I need to use inside my Stored Procedure in SQL Server 2008 R2. I… Read more First Aggregate Function Which I Can Use With Having Clause

SELECT query I am using: SELECT ARRAY[table_name,pg_size_pretty(table_size)] FROM ( SELECT … Read more Array Not Being Returned By Select Query Inside Plpgsql Test Case

Suppose I have the following table definition: CREATE TABLE x (i serial primary key, value integer… Read more Is There A Better Way To Calculate The Median (not Average)

I´m building a grid mechanism where I need to retrieve data from Database the total or records foun… Read more Sql Get Row_number And Count On Every Select Request

I was trying to execute this following query, and I am a beginner in writing SQL Queries, was wonde… Read more Aggregates Not Allowed In Where Clause In Postgresql Error

I have a table with two columns wind_speed and wind_direction. I want to have a custom aggregrate f… Read more Postgres Aggregrate Function For Calculating Vector Average Of Wind Speed (vector Magnitude) And Wind Direction (vector Direction)