What are the methods for implementing recursive queries in mysql?

Methods to implement recursive queries are: 1. Use stored procedures to implement recursive queries. Stored procedures can use loops or recursive calls to implement recursive queries; 2. Use the WITH RECURSIVE statement to specify in the recursive expression The recursive termination condition and the recursive iteration operation can realize the recursive query; 3. By connecting the table with itself and using the connection condition to limit the depth of the connection, the recursive query can be realized; 4. By storing the recursive intermediate in the temporary table Results, and using loops or recursive calls to iteratively calculate, recursive queries can be implemented.

The main methods for MySQL to implement recursive queries are as follows:

1. Use stored procedures: MySQL can be implemented using stored procedures. Recursive query. A stored procedure is a set of precompiled SQL statements that can be defined and executed in the database. Recursive queries can be implemented by using recursive calls in stored procedures. Stored procedures can use loops or recursive calls to implement recursive queries, depending on the specific business requirements.

2. Use the WITH RECURSIVE statement: MySQL version 8.0 and above supports the use of the WITH RECURSIVE statement to implement recursive queries. The WITH RECURSIVE statement can define recursive expressions in the query and use recursive calls to implement recursive queries. Recursive queries can be implemented by specifying the recursive termination condition and the recursive iteration operation in the recursive expression.

3. Use join table query: You can use join table query in MySQL to implement recursive query. Join table query is a method of joining multiple tables together for query. Recursive queries can be implemented by joining a table with itself and using join conditions to limit the depth of the join. Join table queries can be implemented using join operations such as INNER JOIN, LEFT JOIN or RIGHT JOIN.

4. Use temporary tables: Temporary tables can be used in MySQL to implement recursive queries. A temporary table is a table that is temporarily created during a query and can be used to store intermediate results. Recursive queries can be implemented by storing the intermediate results of the recursion in a temporary table and using loops or recursive calls to iterate the calculations. Temporary tables can be created using the CREATE TEMPORARY TABLE statement and operated using operations such as INSERT, SELECT, and UPDATE.

It should be noted that the choice of the above methods depends on the specific business requirements and MySQL version. Stored procedures and join table queries are more common methods and can be used in earlier MySQL versions. The WITH RECURSIVE statement and temporary tables are new features introduced in MySQL 8.0 and above, which can provide a more concise and efficient recursive query method.

In summary, MySQL methods for implementing recursive queries include using stored procedures, WITH RECURSIVE statements, join table queries and temporary tables. Choosing the appropriate method depends on your specific business needs and MySQL version.

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