Database.Guide – Page 297

SQL MIN() for Beginners

July 23, 2023December 7, 2020 by Ian

In SQL, the MIN() function is an aggregate function that returns the minimum value in a given expression.

Below are some basic examples to demonstrate how it works.

SQL COUNT() for Beginners

July 23, 2023December 7, 2020 by Ian

In SQL, the COUNT() function is an aggregate function that returns the number of items found in a group.

You can use COUNT() in multiple parts of a query. For example, you can use it in the SELECT list, or the HAVING clause when filtering groups.

SQL HAVING Clause for Beginners

December 7, 2020December 6, 2020 by Ian

In SQL, the HAVING clause can be used to specify a search condition for a group or an aggregate.

The HAVING clause is typically used with the GROUP BY clause. In cases where it’s not, there is an implicit single, aggregated group.

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.

Find Out Which Partition a Given Value Would be Mapped to in SQL Server (T-SQL)

December 6, 2020 by Ian

If you have a partitioned table or index in SQL Server, and you want to determine which partition a given value would be mapped to, you can do this nice and quickly with the $PARTITION system function.

All you need to know is the name of the partition function (and of course, the value you’re interested in).

SQL GROUP BY Clause for Beginners

December 7, 2020December 5, 2020 by Ian

In SQL, the GROUP BY clause can be used to divide the results of a query into groups of rows.

This is usually done in order to perform one or more aggregations on each group.

SQL ORDER BY Clause for Beginners

December 5, 2020 by Ian

The ORDER BY clause is commonly used in SQL to sort the results of a query.

It allows you to specify the order in which the results are returned.

You can specify whether the results are sorted in ascending order or descending order. You can also specify multiple columns for sorting.

How Implicit Transactions Work in SQL Server

November 11, 2025December 5, 2020 by Ian

There are four transaction modes in SQL Server. One of these is implicit mode.

In SQL Server, an implicit transaction is when a new transaction is implicitly started when the prior transaction completes, but each transaction is explicitly completed with a COMMIT or ROLLBACK statement.

This is not to be confused with autocommit mode, where the transaction is started and ended implicitly.

SQL Transactions Tutorial

December 18, 2025December 4, 2020 by Ian

In SQL, transactions are used to maintain data integrity by ensuring that a sequence of SQL statements execute completely or not at all.

Transactions manage sequences of SQL statements that must be executed as a single unit of work, so that the database never contains the results of partial operations.

When a transaction makes multiple changes to the database, either all the changes succeed when the transaction is committed, or all the changes are undone when the transaction is rolled back.

How to Fix “Conversion failed when converting the value to data type” in SQL Server

December 4, 2020 by Ian

SQL Server error Msg 245, Level 16 tells us that there was a problem when trying to convert a value to a specific data type.

You’ll get this error if you try to insert the wrong data type into a column.

To fix this issue, make sure the data type of the value you’re trying to insert, matches the column’s type.