Several time i need to groups some values in one column and make it into one single column which separated by commas, for example when i have table category_product which is contains column productId, productName, and category. Foreach category of a product stored on a single row entry and each products can have more than one category. To select each product and its categories then make list of categories within single row for each product. On complex way with create such a procedure thas has a loop and concate all category on a variable maybe can solved the problem. But yes.. it needs a time and more effort, so why we not use the easy way? There is GROUP_CONCAT on MySQL or LISTAGG on Oracle that can group value from some column and group them by specific id into single strings. GROUP_CONCAT on MySQL Syntax: group_concat( column_name ) or group_concat( column_name separator ' separator_type ') Example: select id, group_concat(category) from table1 group by id; s...
notes outside of my mind, a simple way to put this mind easy