Found 4401 Articles for MySQL

In SQL Server, there are a number of different techniques to combine records into strings. Different methods to combine rows into a string which we will study in this tutorial − COALESCE XML PATH STRING_AGG First approach: COALESCE To combine many rows into a single string using the COALESCE method, first, create a variable of type varchar to hold the coalesced strings, then use a comma to separate each row's string values. Finally, apply the COALESCE to the variable. Syntax Select column_name1, column_name2, .. from table_name Declare @variable1 Varchar(MAX), @variable2 Varchar(MAX), ..; Select @variable1 = COALESCE(@variable1 ... Read More

There is a rising trend toward using unconventional database types in an effort to efficiently accommodate the variety of data and fulfill the growing need for data storage. Relational databases have been the standard for many years. However, as markets evolve and storage costs decline, non-relational databases are becoming popular. Columnar databases are appropriate for this. These NoSQL databases were designed for challenging, intricate queries. Columnar databases, in contrast to relational databases, store data in columns instead of rows. Subgroups are created by combining these columns. This kind of database has movable keys and column names. The amount of rows ... Read More

We shall view a Cassandra Collection Data Types tutorial along our Cassandra trip. In this, we will learn about Cassandra's Collection data type. These are data types in the same sense as arrays and structures in C, C++, etc. In addition, we will talk about the Cassandra Collection Data Types using list, set, and map. Consequently, let's begin with Cassandra Collection Data Types. Collection Data Types for Cassandra In Cassandra, a collection data type is essentially a storage container for several values. Typically, the Cassandra-CQL collection data type is defined by a single variable. This variable itself has a range ... Read More

Edgar F. Codd, a forerunner of the relational model for databases, presented a set of thirteen rules (numbered zero to twelve) to specify what is needed from a database management system in order for it to be regarded as a relational database management system (RDBMS). They're also known as "Codd's Twelve Commandments." Rule 0: The fundamental principle Any system that claims to be a relational database management system must be capable of managing databases only using its relational capabilities. Rule 1: The information rule A clear logical representation of every piece of information in a relational database is provided ... Read More

A deductive database in SQL or any other database system is a tool that can draw conclusions about new facts based on the rules and information already present in the database. In deductive databases, datalog is the language commonly used to express facts, rules, and queries. The formula, when expressed in clausal form, consists of a number of clauses, each of which is made up of a number of literals joined exclusively by logical connectives marked with the OR symbol. The following quantifiers are possible in a formula − Universal quantifier − It may be read as "For all x, ... Read More

As a developer or system administrator, it's crucial to ensure your MySQL database is running optimally to prevent downtime and maintain fast response times. Fortunately, Linux offers a range of powerful command-line tools that allow you to monitor MySQL's performance in real-time and diagnose any issues that may arise. In this article, we will explore four useful command-line tools that you can use to monitor MySQL performance in Linux. Top Command The top command is a popular Linux utility that enables you to monitor overall system performance, including MySQL processes. top command displays a real-time view of system's CPU usage, ... Read More

Introduction Docker Compose is a tool for defining and running multi-container Docker applications. It allows developers to define their application stack as a YAML file, making it easy to spin up complex environments with just a few commands. However, using private repositories with Docker Compose can be tricky. In this article, we'll explore how to use Docker Compose with private repositories, covering different authentication methods and their examples. What are Private Repositories? Docker images can be stored in private or public repositories. Public repositories are open to everyone, while private repositories require authentication to access them. Private repositories are often ... Read More

Introduction Docker is a popular platform for deploying and running applications in a containerized environment. It provides an efficient way to package, distribute and run applications with all their dependencies. One of main advantages of using Docker is that it enables use of multiple databases in an efficient way using docker-compose. Docker-compose is a tool for defining and running multi-container Docker applications. It allows you to define configuration of different containers in a single YAML file, which can be used to start, stop and manage containers. In this article, we will discuss how to use multiple databases with Docker-compose. Prerequisites ... Read More

The important statistics collected for a performed query, including time, temporary tables, indexes, joins, and more, are gathered in the Query Stats SQL editor results tab (see the following two figures). Requirements Enabled query, and collect performance schema statistics. The performance_schema has statement instrumentation enabled. SQL Editor: Query Stats Visual Explain Plan By utilizing the additional data included in the enhanced JSON format, the visual explain feature creates and presents a visual depiction of the MySQL EXPLAIN statement. All EXPLAIN formats, including the standard format, the raw extended JSON, and the visual query plan, are available in ... Read More

The controls listed below can be used to examine and export performance report data (see the following figure) − Export − Export all entries from the current performance report, including all queries and values, together with any associated data (including column headings). opens an export file dialogue. Copy Selected − Copies a single entry from the current performance report together with any related data (and column titles). the system's clipboard is saved. a case in point Query Copy − This function copies the SQL statement that produced the performance report. the system clipboard is saved. Refresh − The performance ... Read More