MySQL is an open source relational database management system that is widely used for backend data storage and management of web applications. In MySQL, data type design and coding skills are one of the key factors, which have a significant impact on program performance, storage space, and data integrity. This article will introduce data type design and coding skills in MySQL so that developers can choose and use suitable data types and optimize storage methods.
1. MySQL data types
The integer type is one of the most commonly used data types in MySQL, including TINYINT, SMALLINT, MEDIUMINT , INT and BIGINT. Among them, TINYINT and SMALLINT occupy 1 and 2 bytes respectively, MEDIUMINT and INT occupy 3 and 4 bytes respectively, and BIGINT occupies 8 bytes. For many applications, INT is the most appropriate integer type.
Floating point type is used to store decimals, including FLOAT, DOUBLE and DECIMAL. Among them, FLOAT and DOUBLE occupy 4 and 8 bytes respectively. The DECIMAL type has higher storage accuracy, but takes up more storage space.
Character type is used to store string data, including CHAR, VARCHAR, TEXT and BLOB. Among them, the CHAR type is used to store fixed-length strings. For example, CHAR(10) means that a string of length 10 is stored; the VARCHAR type is used to store variable-length strings. For example, VARCHAR(255) means that the longest length can be stored is 255. Character strings; TEXT and BLOB types are used to store larger strings and binary data.
Date and time types are used to store date and time data, including DATE, TIME, DATETIME and TIMESTAMP. Among them, DATE is used to store dates, TIME is used to store time, DATETIME is used to store dates and times, and TIMESTAMP is also used to store dates and times, but its range is wider and can store from January 1, 1970 to 2038 1 A timestamp between the 19th of the month.
2. Coding skills of MySQL data types
In order to save storage space and improve query performance, you should try your best to Use the smallest suitable data type. For example, if a number is 0 or 1, it can be stored using TINYINT(1) instead of INT or BIGINT. Additionally, if an integer is non-negative, it can be stored using the UNSIGNED type instead of the SIGNED type.
Although TEXT and BLOB types can store larger strings and binary data, they take up more storage space, and Query speed is slow. To improve storage and query performance, use CHAR and VARCHAR types to store shorter string data whenever possible.
Character encoding is a key design factor in MySQL, which determines how character data is stored and how character comparisons are performed. Common character encodings are UTF-8, GBK, GB2312, etc. For most applications, UTF-8 is the best choice because it supports all Unicode characters and is more space-efficient than other encodings.
Date and time type storage is very convenient in MySQL, but when storing large amounts of date and time data, you should pay attention to storage space and Query performance. For information that only needs to store date and time, you should try to use the DATE, TIME, or DATETIME types. For information that requires high-precision time, you can use the TIMESTAMP type.
3. Conclusion
The data type design and coding skills in MySQL have an important impact on program performance, storage space and data integrity. In order to maximize the use of MySQL database, developers need to choose appropriate data types and store and query data appropriately. By using the smallest appropriate data type, avoiding the use of TEXT and BLOB types, choosing appropriate character encoding, and reasonable date and time storage, you can effectively improve MySQL's operational performance and query efficiency, making our applications more efficient and reliable.
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