mysql converts a string to a number

When I wrote the SQL statement today, I sorted the numbers relative to the string type. How to do it?

Need to be converted to numbers before sorting

1. Use + directly¶

String+0

eg:

select * from orders order by (mark+0)  desc

2. Use functions¶

• CAST(value as type);

• CONVERT(value, type);

Note:

The type here can be:

• float: DECIMAL
• Integer: SIGNED
• unsigned integer: UNSIGNED

eg:

select * from orders order by CONVERT(mark,SIGNED)  desc

select * from orders order by CAST(mark as SIGNED)  desc