select @x:=ifnull(@x,0)+1 as rownum,t.* from xx_product_sale t;
或者：
set @index=0;
select @index:=(@index+1) as idx, id from t_sys_menu;
idxid
110
217
325
426
527
650
754
855
961
1069
1172
1274
1393
1496
15101
16112
17113
18114
19115
2011
2112
2252
23100
24109
2518
2623
2764
2899
2965
3086
3139
3240
3346
3447
3549
3677
3751
3856
3959
4071
41104
4257
4358
4460
4588
4662
4763
4866
4967
5068
5178
5279
5380
5470
5587
5689
5773
5875
5976
6081
6182
6283
6384
6485
6594
6695
6797
6898
69102
70103
