Fix MySQL Multi-Field Sorting Problems

When multiple field sorting is not working, it may be due to incorrect order or data types of the sorting fields. Here are some solutions:

1. Make sure the order of the fields is correct: When using multiple field sorting, ensure that the order of the fields matches the priority of the sorting. For example, if you want to sort by fields A and B, you should first sort by field A, and then sort by field B.
2. Ensure the correct data type for fields: When using multiple field sorting, make sure that the data type of the fields is compatible. If the data type of the fields is not compatible, it may lead to incorrect sorting results. Ensure that the data type of the fields is the same or can be compared.
3. Use the CAST function for conversion: If the data types of the fields are not compatible, you can use the CAST function for conversion. For example, if one field is of a string type and another field is of a numeric type, you can use the CAST function to convert the string field to a numeric type and then sort it.
4. Check for null values: If there are null values in the sorting fields, it may result in incorrect sorting. When sorting with multiple fields, ensure there are no null values present or use the COALESCE function to convert null values to a default value for sorting.

By using the above method, the issue of ineffective sorting for multiple fields can be resolved. Ensuring the correct order, data type, and values of the sorting fields will result in the correct sorting outcome.