Problem You have a table with a column where some rows contain NULL values or empty strings. You want to retrieve rows where this column has a value (i.e., not NULL and not an empty string). Input product_id product_name product_description 1 Laptop High performance gaming laptop 2 Mouse 3 Keyboard 4 Monitor 27 inch 4K …
How to return results only if value exists in SQL? Read More »
Problem You have a table with multiple records. For each distinct value in one of the columns (i.e., each ‘group by’ group), you want to retrieve the top ‘n’ rows based on some criteria. In the below example, get the top 2 entries for each sales person based on ‘amount’ column. Input id salesperson amount …
How to get top n results in each ‘group by’ group in SQL? Read More »
Problem You have a table with multiple rows of data for each unique identifier and you want to concatenate the values of these rows into a single field for each identifier. Input user_id interest 1 Reading 1 Writing 2 Painting 2 Singing 3 Traveling Try Hands-On: Fiddle Create Table: Gist Desired Output user_id concatenated_interests 1 …
How to concatenate multiple rows into one field in MySQL? Read More »
