Tag: sql | makolyte

SQL – Aggregate functions with GROUP BY

01/26/202501/06/2023 by Mak

There are five main aggregate functions in SQL: COUNT(), SUM(), AVG(), MIN(), and MAX(). These calculate aggregate values for sets of rows. When you use them with GROUP BY, they calculate the aggregate values for each group. Let’s say you want to get movie streaming stats for each user. Here’s an example of using GROUP … Read more

SQL – Using GROUP BY with ORDER BY

01/26/202501/05/2023 by Mak

GROUP BY groups rows based on one or more columns. ORDER BY sorts rows. You can use these together to sort groups. There are two options you can use for sorting groups: I’ll show examples below. At the end, I’ll talk about how SQL Server may implicitly sort groups (and why you shouldn’t depend on … Read more

SQL – How to use GROUP BY

01/26/202504/26/2022 by Mak

You can use GROUP BY to group rows based on one or more columns. This produces one row per group in the query results. Each group contains the grouping columns and the result(s) of any aggregate function(s) (COUNT/MIN/MAX/AVG/SUM) you want to use on the group. Let’s say you have the following table and you want … Read more

SQL Server – Copy data from one table to another

01/26/202501/24/2022 by Mak

To copy data from one table to an existing table, use INSERT INTO SELECT and specify the column list: If the columns are the exact same in the two tables (and there are no identity columns), you don’t need to specify the column list: When the table doesn’t exist, use SELECT INTO, specifying which columns … Read more

SQL – Select from information_schema.columns

01/26/202506/16/2021 by Mak

You can query the information_schema.columns system view to get information about all columns in the database. Here’s an example: Here’s the first few rows this returns: TABLE_NAME COLUMN_NAME Movies Id Movies Title Movies Year In this article, I’ll show more examples of querying information_schema.columns. Get columns filtered by name Let’s say you want to find … Read more

Case sensitivity in SQL Server

01/25/202506/10/2021 by Mak

In SQL Server, the collation property controls case sensitivity. Case sensitivity affects sorting and queries (even the column names must match exactly if you’re using a case-sensitive collation at the database-level). The default collation when you create a database in SQL Server is SQL_Latin1_General_CP1_CI_AS. The CI stands for case-insensitive, which means SQL Server databases are … Read more