subqueries – Page 3

Understanding the ARRAY Constructor in PostgreSQL

September 17, 2024May 1, 2024 by Ian

In PostgreSQL we can create arrays with the ARRAY constructor. An array constructor is an expression that builds an array value using values for its member elements.

Fix Msg 512 “Subquery returned more than 1 value” in SQL Server

September 17, 2024February 21, 2022 by Ian

If you get error Msg 512 that reads “Subquery returned more than 1 value…” in SQL Server, it’s because you’re using a subquery that returns more than one value in a scenario where this is not allowed.

SQL SELECT for Beginners

September 17, 2024December 6, 2020 by Ian

The SELECT statement is almost without doubt, the most commonly used statement in SQL.

The SELECT statement is used for retrieving data from the database. You can specify which rows you want returned, and which columns.

SQL EXISTS Operator for Beginners

September 17, 2024November 30, 2020 by Ian

In SQL, the EXISTS operator specifies a subquery to test for the existence of rows. It returns TRUE when the subquery returns one or more rows.

A subquery is a query that is nested inside another query (or even another subquery)

This article contains some basic examples of the EXISTS operator.

SQL IN Operator for Beginners

September 17, 2024November 30, 2020 by Ian

In SQL, the IN operator allows you to filter your query results based a list of values.

You can also use it to match any value returned by a subquery (a subquery is a query that’s nested inside another query).