根据您提供的链接，其外观应如下所示:

According to the link you gave it should look like this:

SELECT    a.*,
( 
            CASE a.field1 
            WHEN @curType 
            THEN @curRow := @curRow + 1 
            ELSE @curRow := 1 AND @curType := a.field1 END
          ) + 1 AS rank
FROM      table_a a,
          (SELECT @curRow := 0, @curType := '') r
ORDER BY  a.field1, a.field2 desc;

根据您提供的链接中的示例，这里有2个小提琴，一个是oracle，一个是mySql.

Here are 2 fiddles, one for oracle and one for mySql based on the example from the link you gave:

1. oracle
2. Mysql

1. oracle
2. Mysql