MySQL is a relational database management system (RDBMS). In simple English, RDBMS is software which is used to store and retrieve data, and manage permissions as to who or what services can access that data. Structured Query Language (SQL) is a powerful and widely used language to create and manage relational databases. MySQL uses SQL as its language to interact with the database.
One of the key aspects of MySQL is its support for various data types that enable efficient storage and retrieval of different kinds of data. MySQL data types include numeric data types such as integers and decimals, character and string data types, date and time data types, enum and set data types, and binary data types. Understanding the different data types and how they are used is essential for you to have effective database design and query optimization.
Now that you know a little more about data types and how they play a role in MySQL, let’s talk about the various MySQL data types that are also supported by the MySQL database management system.
MySQL supports several string data types that are used to store character and text data. The most commonly used string data types are:
CHAR(n) is a fixed-length character string that can store up to n characters. If the actual length of the string is less than n, spaces are added to pad the string. VARCHAR(n) is a variable-length character string that can store up to n characters. The actual length of the string is stored, so only the space required by the string is used.
TEXT is a variable-length character string that can store up to 2^31-1 bytes (about 2GB) of text data. This type is often used to store large amounts of text data, such as documents or web pages. Some MySQL data types additionally include TINYTEXT, TEXT, MEDIUMTEXT, and LONGTEXT, which can store up to 255 bytes, 64KB, 16MB, and 4GB of string data respectively, while these particular MySQL data types are not present in other database systems such as PostgreSQL.
ENUM is an enumeration that refers to a data type that represents a set of fixed-length strings with predefined values.
Numeric data types in MySQL are used to store numerical values such as integers and decimal numbers. These data types are an essential component of databases as they allow for mathematical operations to be performed on data within the database. They are also used as auto-increment primary keys, referring to the last primary key that was inserted into the table. Some of the most commonly used numeric data types are the integer, floating point numbers, and decimal point data types. MySQL offers support for all standard SQL numeric data types, including TINYINT, SMALLINT, MEDIUMNINT, INT, and BIGINT as well as DECIMAL, NUMERIC, FLOAT, DOUBLE, and BIT types . The full list of MySQL numeric data types is covered in detail from the MySQL official documentation, which includes additional data such as the ranges for each data type, syntax, and the accuracy of items like double precision to better enhance your decisions.
Spatial data types in MySQL are used to represent and store geographic or spatial data, such as points, lines, polygons, and other geometric shapes. These data types are used in various applications, such as geographic information systems (GIS), mapping, and location-based services. There are several spatial data types in MySQL, including POINT, which is used to store a single point in space. A point is represented by a set of coordinates that define its location in a two-dimensional or three-dimensional space. A full list of MySQL spatial types as an example can be found in MySQL’s documentation. SQL also supports spatial functions and operators that allow for spatial analysis and manipulation of spatial data. For example, MySQL provides functions for calculating distances between points, determining if a point is inside a polygon, and calculating the area of a polygon.
Date and time data types are used to store and manipulate temporal data, such as dates (hh:mm:ss), times, timestamps (yyyy-mm-dd hh:mm:ss), time intervals, and date and time together (yyyy-mm-dd hh). These time data types are essential in many applications, including scheduling, event management, and financial transactions. One great thing about date and time types is that we can use the ss format, which allows us to format string data types, timestamps, and more. The most commonly used date and time data types in SQL are DATE, TIME, DATETIME, and TIMESTAMP. While the DATETIME and TIMESTAMP stores both the date and time values in one data type, the first two individually store date or time respectively.
Binary string data types in SQL are used to store binary or non-textual data, such as images, audio files, video files, and other types of binary data. There are several binary data types in MySQL, including BLOB (Binary Large Object). This data type is designed specifically for storing large amounts of binary data, such as images or video files. BLOBs can usually store up to 4GB of data, making them ideal for multimedia applications.
Other binary data types include BINARY, a fixed-length binary data type, and VARBINARY, a variable-length binary data type. For example, if you define a column as BINARY(10), it will always store 10 bytes of data, whereas if a column is defined as VARBINARY(20), it means it can store up to 20 bytes of data. If you know the size of the data will always be the same, using BINARY may be more efficient, but if the size of the data varies, VARBINARY is the better choice. For more information on binary string data types, you can check this video on MySQL binary strings.
JSON is a popular data format used for storing and exchanging data on the web, and it is commonly used for representing complex and hierarchical data structures. By allowing JSON data to be stored directly in a MySQL column, it eliminates the need to serialize and deserialize the data, making it faster and more efficient to work with. It also provides added compatibility when working with web applications, making it easier to integrate with, and it can also be used when storing configuration data for an application such as settings and preferences or storing user-generated content. Use JSON columns in situations where there is no well-defined schema or the schema changes frequently.
Data types enforce rules that ensure the correct type of data is stored in a column, preventing errors and maintaining data integrity. In addition, using appropriate data types can also improve query performance by reducing the need for type conversions during query execution. They also provide a way to validate data input, ensuring that data is formatted correctly and preventing incorrect data from being stored in the database. Choosing the appropriate data type can also help to optimize storage requirements by minimizing the amount of disk space required to store data. An example of incorrect data type selection in a MySQL table which has numeric columns is that all are defined as INT, even though some of the columns can be defined as TINYINT (as the value is between -128 and 127). If their MySQL data type was actually defined as TINYINT, that extra storage space would not be unnecessarily reserved, hence saving disk space overall and freeing it for other tables and columns. Having the right data types can also increase database speed. When your database doesn’t have to spend extra time searching for the data, it can run faster. It can also help improve indexing efficiency and speed. That’s because the appropriate data types take up less memory.
In conclusion, data types are an essential component of MySQL databases, as they define the type of data that can be stored in a database column and how that data can be manipulated. By choosing the appropriate data types for each column, you can ensure efficient storage and retrieval of data and maintain data integrity.