This Is Your Brain On Informatics: Q&A

MariaDB Examples

Manually Creating a Table

This data table was uploaded as a TSV (tab separated values) file.

LOAD DATA INFILE '[data table pathname]' INTO TABLE `test` FIELDS TERMINATED BY '\t' OPTIONALLY ENCLOSED BY '"' LINES TERMINATED BY '\r\n' IGNORE 1 LINES

Quintiles

Q: Find the maximums in column 2 of quintiles based on column 1

The following will create a temporary table that will order [var1], hold [var2] and also create a column with a counter variable named "id".

A: CREATE TEMPORARY TABLE `rank` (id BIGINT UNSIGNED AUTO_INCREMENT PRIMARY KEY) SELECT [var1],[var2] FROM `test` WHERE [var3] = "string" AND [var1] <10000000 ORDER BY [var1];

Then the use of the next command will need to be repeated for each quintile to find the maximum for each one.

A: SELECT MAX([var2]) FROM `rank` WHERE id BETWEEN [calculated lower bound of quintile] AND [calculated upper bound of quintile];