If you’ve ever encountered a SERIAL column in a MySQL database, you might’ve wondered how it differs from an AUTO_INCREMENT column. After all, they both generate values that automatically increment?
Read on to find out what the difference is between SERIAL and AUTO_INCREMENT in MySQL.
In SQL Server, when we use FOR XML to return query results in an XML document, the resulting XML document is returned as a string by default. However, we can change this so that it’s returned in the xml data type.
To do this, all we need to do is append our query with the TYPE directive.
In PostgreSQL we can create auto-incrementing columns using the serial data type. The serial type causes the column to be automatically populated with an auto-incrementing value each time a new row is inserted. The same applies for the smallserial and bigserial types.
This article provides an overview of how these data types work.
Continue readingPrior to PostgreSQL 10, if we wanted to create an auto-incrementing column, we would typically use the SERIAL type, or we’d create our own sequence and apply it to an integer column.
But from PostgreSQL 10 onwards, we’ve been able to create identity columns.
Continue readingWhen creating a sequence object in SQL Server, the default data type is bigint. However, we can change this so that the sequence uses a data type of our choosing, as long as it’s an integer type (see below for accepted data types).
We can set the data type of a sequence by using the AS argument when defining the sequence.
The integer data type is probably one of the more common data types when working with database management systems (and with computing in general). The integer is a numeric data type that allows us to store certain kinds of numbers.
More specifically, an integer is the number zero (0), a positive natural number (e.g. 1, 2, 3, …) or a negative integer with a minus sign (e.g. −1, −2, −3, …). Integers contain no decimal or fractional part.
However, many computing environments distinguish between signed integers and unsigned integers.
Let’s take a look at the difference between signed integers and unsigned integers.
Continue readingIn SQL, the columns information schema view, which returns information about columns, is an ISO standard view that is supported by most of the major RDBMSs. You can use this view to get information about a column’s data type.
Most of the major RDBMs also provide other methods for getting column information.
Here are examples of getting the data type of a column in various SQL databases.
Continue readingMariaDB provides multiple ways of returning the data type of a column. Here are four ways to get the data type of a given column in MariaDB.
Continue readingIn SQLite, there are quite a few ways to look at a table’s structure. Therefore, there are quite a few ways we can check the data type of the columns within that table.
There’s also a function that allows us to check the data type of a column returned in a query.
Here are five ways to check the data type of a column in SQLite.
Continue readingHere are three ways to get the data type of a given column in MariaDB.
Continue reading