Tag: what is

What is a Format String in SQL Server?

Posted on by Ian

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

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What is the Year 2038 Problem?

Posted on by Ian

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.

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What is Azure Data Studio?

Posted on by Ian

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.

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JSON_ARRAY_APPEND() – Append Values to a JSON Array in MySQL

Posted on by Ian

When using JSON documents with MySQL, we can use the JSON_ARRAY_APPEND() function to append new values to an array.

The way it works is, you provide the JSON document as the first argument, then follow that up with the path to append to, followed by the value to append.

In MySQL 5.7, this function was called JSON_APPEND() but that name is no longer supported.

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What is T-SQL?

Posted on by Ian

Transact-SQL, often abbreviated to T-SQL or even TSQL, is Microsoft’s and Sybase’s proprietary extension to SQL. Transact-SQL expands on the SQL standard to include extra features that aren’t included in the SQL standard.

Here’s an example of a simple T-SQL statement:

CREATE DATABASE Movies;

This is as simple as a T-SQL example could get. This creates a new database called Movies.

However, T-SQL provides for other options to be included in this statement, such as where the database files should be located, the size of those files, what their maximum size should be, and more.

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What is LENGTH() in MySQL?

Posted on by Ian

One of the many functions in MySQL is the LENGTH() function, which returns the length of a string, measured in bytes.

Example:

SELECT LENGTH('Lit');

Result:

+---------------+
| LENGTH('Lit') |
+---------------+
|             3 |
+---------------+

This is a simple example and the result is the same as if we’d used the CHAR_LENGTH() function. However, the LENGTH() function can return different results, depending on the data type.
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What is Collation in Databases?

Posted on by Ian

In database systems, Collation specifies how data is sorted and compared in a database. Collation provides the sorting rules, case, and accent sensitivity properties for the data in the database.

For example, when you run a query using the ORDER BY clause, collation determines whether or not uppercase letters and lowercase letters are treated the same.

Collation is also used to determine how accents are treated, as well as character width and Japanese kana characters. Collation can also be used to distinguish between various ideographic variation selectors in certain collations (such as the Japanese_Bushu_Kakusu_140 and Japanese_XJIS_140 collations that were introduced in SQL Server 2017).

Different database management systems will provide different collation options. Depending on the DBMS, collation can be specified at the server level, the database level, the table level, and the column level. Collations can also be specified at the expression level (so you can specify which collation to use when you run a query), and at the identifier level.
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