Can mysql store arrays

MySQL does not support array types in essence, but can save the country through the following methods: JSON array (constrained performance efficiency); multiple fields (poor scalability); and association tables (most flexible and conform to the design idea of ​​relational databases).

Can MySQL save arrays? The answer is: save the country in a curve!

Many newbies will ask this question. On the surface, MySQL does not directly support array types, but this does not mean you are helpless. MySQL is essentially a relational database, and the structure of rows and columns determines how it processes data. Want to stuff an array into a field directly? That is unrealistic, and the design philosophy of the database and its own structure determine the infeasibility of this approach.

So, how to simulate the function of an array? This requires some skills. I will talk about the most common methods and share some pitfalls and solutions I have encountered in years of development.

Method 1: JSON array

MySQL 5.7 later supports JSON data types, which may be the most convenient and commonly used method. You can directly store the array in JSON format into a field.

 <code class="sql">CREATE TABLE my_table ( id INT PRIMARY KEY AUTO_INCREMENT, data JSON ); INSERT INTO my_table (data) VALUES ('["apple", "banana", "cherry"]'); SELECT data->"$[0]" FROM my_table; -- 获取数组第一个元素</code>

This looks beautiful, right? But don't be too happy too early. JSON's query efficiency, especially complex queries, is usually not as good as using a relational database directly. If you need to frequently perform complex filtering, sorting and other operations on elements in an array, the performance of JSON may drive you crazy. I once had to reconstruct the database design and split the array into multiple rows of data due to excessive dependence on JSON arrays. Therefore, when storing arrays using JSON, be sure to evaluate your query requirements to avoid falling into performance pitfalls.

Method 2: Multiple fields

If your array element count is relatively fixed and you need to query array elements frequently, consider using multiple fields to simulate the array.

 <code class="sql">CREATE TABLE my_table ( id INT PRIMARY KEY AUTO_INCREMENT, element1 VARCHAR(255), element2 VARCHAR(255), element3 VARCHAR(255) ); INSERT INTO my_table (element1, element2, element3) VALUES ('apple', 'banana', 'cherry');</code>

The advantage of this method is that it has high query efficiency, and its disadvantage is that it has poor scalability and fixed array length. Once elements need to be added, the table structure needs to be modified. This can cause great trouble in late-project maintenance, so this method is not recommended unless your array length is very fixed and does not change.

Method 3: Association table

This is the most flexible and most in line with the concept of relational database design. Create an associative table to store array elements.

 <code class="sql">CREATE TABLE my_table ( id INT PRIMARY KEY AUTO_INCREMENT ); CREATE TABLE my_array ( id INT, element VARCHAR(255), index INT, FOREIGN KEY (id) REFERENCES my_table(id) ); INSERT INTO my_table () VALUES (); -- 插入主表INSERT INTO my_array (id, element, index) VALUES (LAST_INSERT_ID(), 'apple', 0); INSERT INTO my_array (id, element, index, ) VALUES (LAST_INSERT_ID(), 'banana', 1); INSERT INTO my_array (id, element, index) VALUES (LAST_INSERT_ID(), 'cherry', 2); SELECT a.element FROM my_array a JOIN my_table t ON a.id = t.id WHERE t.id = 1;</code>

This requires writing a little more code, but it solves the shortcomings of the previous two methods, is good in scale and has relatively high query efficiency. This is my most recommended method, it is more in line with the database paradigm and easier to maintain and expand. Of course, you also need to have a deeper understanding of database design.

All in all, MySQL does not have direct array types, but with clever design we can implement similar functionality. Which method to choose depends on your specific requirements and performance requirements. Remember, there is no perfect solution, only the most suitable one. Before making a choice, you must carefully weigh the advantages and disadvantages of various methods to avoid getting stuck. Only by thinking more and practicing more can you become a real database master!

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