SQL Server ships with a collection of built-in functions that enable you to perform a variety of operations. Each built-in function serves a specific purpose, and can’t be modified. If a function serves your purpose, you can go ahead and use it.
But what if you can’t find a function that serves your purpose?
Then it’s time to write your own user-defined function.
In SQL Server, a scalar UDF, or scalar user-defined function, is a user-defined function that returns a single value.
This is in contrast to a table-valued function, which returns a result set in the form of a table.
User-defined functions can be written as either T-SQL UDFs or CLR (Common Language Runtime) UDFs. CLR enables you to create UDFs in managed code using any .NET Framework programming language. These functions are then accessible to T-SQL or other managed code.
Continue readingIn SQL Server, a table-valued function (TVF) is a user-defined function that returns a table. This is in contrast to a scalar function, which returns a single value.
You can invoke a table-valued function in the same way that you can query a table. For example, you can use it in a SELECT statement. In some cases, table-valued functions can also be used to update, delete, and insert data.
In SQL Server, a computed column is a virtual column that uses an expression to calculate its value.
A computed column will typically use data from other columns in its calculation. If data in any of those columns is updated, the computed column will automatically reflect the update in its calculation.
Continue readingIn SQL Server, the @@MAX_PRECISION configuration function returns the precision level used by decimal and numeric data types as currently set in the server.
No argument is required. You can simply use it in a SELECT statement to return the precision level of the current server.
In SQL Server, the @@TEXTSIZE configuration function returns the current value of the TEXTSIZE option.
No argument is required. You can simply use it in a SELECT statement to return the current TEXTSIZE value.
The TEXTSIZE value specifies the size of varchar(max), nvarchar(max), varbinary(max), text, ntext, and image data returned by a SELECT statement. This value can be set using SET TEXTSIZE.
In SQL Server, rowversion is a data type that exposes automatically generated, unique binary numbers within a database. It allows you to version-stamp table rows with a unique value. This helps maintain the integrity of the database when multiple users are updating rows at the same time.
Each SQL Server database has a a counter that is incremented for each insert or update operation that is performed on a table that contains a column with the rowversion data type (or its timestamp synonym, which is flagged for deprecation).
If a table contains a rowversion (or timestamp) column, any time a row is inserted or updated, the value of the rowversion column is set to the current rowversion value. This is true, even when an UPDATE statement doesn’t result in any changes to the data.
In SQL Server, the FORMAT() function enables you to format date/time and number values as a formatted string by passing in a “format string” as the second argument (the first argument is the value that’s being formatted).
Here’s an example of this function in action:
FORMAT(@date, 'dd/MM/yyyy');
In this case the format string is dd/MM/yyyy.
This particular format string specifies that the @date value should be formatted with a two-digit day, two-digit month, and a four-digit year, in that order, and with forward slashes as the separators.
This would result in something like this:
21/05/2019
The Year 2038 problem (also referred to as the Y2K38 bug) refers to a problem that some computer systems might encounter when dealing with times past 2038-01-19 03:14:07.
Many computer systems, such as Unix and Unix-based systems, don’t calculate time using the Gregorian calendar. They calculate time as the number of seconds since 1 January 1970. Therefore, in these systems, time is represented as a big number (i.e. the number of seconds passed since 1970-01-01 00:00:00). This is typically referred to as Epoch time, Unix time, Unix Epoch time, or POSIX time. As I write this, Unix time is 1560913841. And as I write this next line, Unix time has incremented to 1560913879.
Microsoft Azure Data Studio is a free, cross-platform tool that can be used to manage SQL Server, Azure SQL Database, and Azure SQL Data Warehouse.
Azure Data Studio was formerly called SQL Operations Studio (while it was in preview release), and it was renamed to Azure Data Studio once it was moved to general availability (GA) on September 24, 2018.