如何在选择查询中获取行号

Question

i try this query to get row number in selected rows, but the output comes like 23,56,78,.... i need to get 1,2,3 to every selected row. please help me

SET @row=0;
SELECT `table1`.`col1`,`table1`.`col2`,@row:=@row+1
FROM `table1`
LEFT OUTER JOIN `table2` ON `table1`.`col1` = `table2`.`col5`
WHERE `table2`.`col5` IS NOT NULL
GROUP BY `col1` ORDER BY `table1`.`col7` DESC LIMIT 0,10

Answer 1

Move the query with the ORDER BY clause into a subquery.

SET @row = 0;

SELECT col1, col2, @row := @row+1
FROM (SELECT table1.col1, table1.col2
      FROM table1
      LEFT JOIN table2 ON table1.col1 = table2.col5
      WHERE table2.col5 IS NOT NULL
      GROUP BY col1
      ORDER BY table1.col7 DESC
      LIMIT 0, 10) AS subquery

Answer 2

You can try using an inline view. Use a query that gets the rows you want to return, and then wrap that in parens, and reference that query in the FROM clause of an outer query.

Something like this:

  SELECT v.`col1`
       , v.`col2` 
       , @row := @row + 1 AS `rn`
    FROM ( SELECT `table1`.`col1`
                , `table1`.`col2`
             FROM `table1`
              ... 
            ORDER BY ...
            LIMIT 10
         ) v