Before understanding the MySQL tutorial, let’s first understand what is database. A database is a set of tables that allows you to store data. The data can be stored in a structured form called records which are made up of fields. Fields typically contain alphanumeric characters. However, they may contain other characters, such as numbers and special symbols. Each field has a specific name, and each record has a unique identifier called a primary key (unique identifier).
The database provides more robust features than just keeping simple records. It allows you to compare, add, modify or delete records if the record meets the condition set by the programmer before it is modified or updated in the database table structure. This means you need to know SQL to manipulate data stored in a database table structure successfully. This MySQL tutorial for beginners will guide you on the basics of MySQL knowledge.
What is MySQL
MySQL is an easy-to-use database management system (DBMS) and a popular choice for many small companies, web applications, and Internet websites. The term MySQL refers to the MySQL server software that is installed on any computer with web servers (such as Apache).
The MySQL software handles all database tasks, such as reading/writing data efficiently. It is definitely one of the best options for managing large databases because it runs very quickly and efficiently with its indices that are used for data storage.
When you place your PHP code in the database, it can run queries and assign data to variables more efficiently. It also makes it easier for web programmers to develop their database-driven websites without having a separate SQL database management system.
MySQL is designed as a fast, easy-to-use, scalable database management system even in large internet applications. MySQL is an open-source software package which means that its source code is freely available, and anyone can take a look at its different methods of coding and make any changes to the source code if he or she desires. This article on how to learn MySQL database step by step will guide you effectively.
The four categories of MySQL commands
There are four different types of MySQL commands that are used to manipulate data. They are:
Data definition language (DDL) commands
This command is used for database creation and manipulation (adding, deleting, and modifying database information). Some of the examples of these commands include the CREATE and ALTER commands. DDL is mainly used to define the MySQL server. DDL should be the first thing that one should learn on MySQL basics.
Data manipulation language (DML) commands
This type of command is used to retrieve, update, insert and delete data from the database. Some examples of this type include the SELECT, UPDATE, INSERT and DELETE commands. It is mainly used to read and write data from the database.
Data control language (DCL) commands
This type of command is used to grant users privileges and change other database settings. These commands are also used for adding and removing users from databases. Some examples include GRANT, REVOKE, and SET commands.
The DCL command controls access privileges to the database or its specific objects within a database. This command includes CREATE user, DROP user, and GRANT/REVOKE statements. This command is also useful in enforcing the user’s rights to the database itself or any of its objects within it.
Transaction Control Language (TCL) commands
Transaction control language is a MySQL extension to standard SQL language and is useful in managing database transactions. It is used to cancel, roll back and commit transactions. Some examples include the SET TRANSACTION command, BEGIN … END COMMIT commands, and ROLLBACK statements. It is mainly used for keeping track of all the changes that are pending to be made in a database.
Types of Database Keys
There are mainly five types of database keys that we are going to learn in this MySQL tutorial for beginners with examples:
These are used to store unique data values. The primary key is automatically generated for tables that contain a primary key constraint in the CREATE TABLE statement. A very important thing to note here is that the value of the primary key depends upon the name of the table and its column definition. The first, second, and third elements in a primary key must be alphanumeric characters. It should also be noted that if there are multiple columns in a table with the same name and a null value is inserted into one of them, all of them will be null values.
Though this is not a primary key, it has the same characteristics as a primary key. These keys are used to keep track of records that belong to a group and uniquely identify them within the group. They cannot contain null values since they are used to relate multiple tables that have different primary keys together.
A foreign key is used to relate one table’s data with another table’s data. These are used when you want to store data from one table to another. They are not required for all kinds of relationships between two tables, but they help out when there are many relationships between two or more tables.
This is similar to the primary key, it is used to define the integrity of a table. These keys are used in tables that store hierarchical data, for example, parent-child relationships.
This is similar to a candidate key in the sense that it is not a primary key but can be used to divide data into groups. They are used in tables that store hierarchical data, for example, parent-child relationships.
Constraints used in MySQL database
There are several constraints that are used in MySQL database that we will learn on this MySQL basics for beginners, and they include:
It assigns a value to a column if it is null. The Null column can be used to validate the values of a column before inserting them into a table. For example, suppose you have tables A and B, then column A has constraints NULL, and columns B and C have constraints NOT NULL. After data insertion into table A, it will not be possible for row 1 in any of the columns in table A to contain only null values for all its fields.
Unique Constraint specifies that a column should not contain duplicate values. It is used to check the uniqueness of data added to a table. Primary Key
In this Constraint, the value of a column must be unique within the table. It is used to give unique names to each row of a table. For example, suppose you have tables A, B, and C, then column A has the constraint PRIMARY KEY, while columns B and C have constraints NOT NULL. This Constraint assigns unique names to each row in a table.
Check Constraint used in MySQL database
CHECK Constraint is used when you want to make sure that data entered in one column of the table cannot be entered in another correspondent field. For example, suppose you have tables A and B, and column A contains various values pertaining to table B. This is possible only if you have a check constraint on values in column A.
The default constraint is used to define the Default value of a column. For example, suppose you have two columns in table A, ID and Weight and both of these columns have default values 1 and 150, respectively. Whenever you insert values into tables, the default constraint will assign default values to fields as appropriate.
INDEX Constraint is used to assign a unique index to each table. This Constraint is used to ensure that each row in a table exactly matches the values of every column in a single index.
JOINS on MySQL Database
JOIN Operations are used in order to combine data from multiple tables into a single result set. It is viewed as the “glue” that holds data together. Following are the types of joins that can be performed on the MySQL database:
This join type combines data from multiple tables into a single result set. This method is also called the equi join method because it joins records that have matching values in their join columns. This type of join is usually used to compare and analyze values.
Left Outer Join
The left outer join is used to get all the records from a table and also to get any additional records from another table specified in the FROM clause. This type of join is also called an anti-join because it gets all the records (except those of null values) from one table named in the FROM clause.
Right Outer Join
The right outer join is used to get all the records from a table and also gets any additional record entries that contain NULLs. The right outer join is also called an anti-join because it joins rows that have matching values in their join columns.
Full Outer Join
The full outer join is used to get all the records from a table and any additional record entries containing NULLs. This type of join is also called an anti-join because it joins rows with matching values in their join columns.
This join combines data from multiple tables into a single result set. It works like a cross between a left outer and right outer join. This method joins records with matching values in their join columns but eliminates any null values present in the result set.
In conclusion, MySQL can be used in various applications requiring data storage, manipulation, and retrieval. It is easily accessible, as it is available through web browsers and its database management system (DBMS) is well structured. Since MySQL runs on open-source software, it enjoys enormous support from its users despite its relative life span. From the above MySQL tutorial for beginners, you have learned MySQL basics. Sign in for more information.
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FAQ – Frequently Asked Questions
1. What is MySQL?
MySQL tutorial explains both fundamental and sophisticated MySQL principles. Both professionals and beginners can benefit from our MySQL training. The popular language for organizing and accessing database records is called Structured Query Language, and MySQL is a relational database management system built on this language.
2. Why Should We Learn MySQL?
We should learn MySQL for a variety of reasons, some of which are listed here.
- Options for employment: Since MySQL employs SQL queries, typical of relational databases like Oracle, SqlServer, etc., you might be a successful Backend Database Engineer.
- Free Software: The use of MySQL is free because it is an open-source database.
- MySQL performs better security: A MySQL super admin can create and administer a variety of roles from the other access and roles that are accessible. Users can also carry out restricted operations on the database since Super Admin can award parts with limited functions. It secures our database.
3. What Are The Different Types Of Keys In MySQL Tutorial?
- A candidate key is the bare-bones set of characteristics that can successfully identify a tuple.
- Super Key – The group of characteristics that can each identify a tuple specifically is referred to as Super Key. S
- A primary key is also a group of characteristics that can be used to distinguish each tuple from the others.
- A candidate key that is not the primary key is referred to as an alternate key.
- The foreign key to the attribute to which it relates is an attribute that can only accept the values now existing as the values of some other attribute.