# SQL 语句执行计划不准 - 索引分析（A）

+ 2 个列分别都有索引

```
mysql> SELECT COUNT(*) FROM tods.bus_jijin_trade_record WHERE id >= 177045000;
+-----------+
| COUNT(*)  |
+-----------+
| 145917327 |
+-----------+
1 row in set (16.86   sec)

mysql> SELECT COUNT(*) FROM tods.bus_jijin_trade_record WHERE updated_at > date_sub(now(), interval 48 hour);
+-----------+
|  COUNT(*) |
+-----------+
|    713682 |
+-----------+
```

-------------------------------------------------------------
```
mysql> SELECT COUNT(*) FROM tods.bus_jijin_trade_record WHERE id >= 177045000;
+-----------+
| COUNT(*)  |
+-----------+
| 145917327 |
+-----------+
1 row in set (16.86   sec)

mysql> SELECT COUNT(*) FROM tods.bus_jijin_trade_record WHERE updated_at > date_sub(now(), interval 48 hour);
+-----------+
|  COUNT(*) |
+-----------+
|    713682 |
+-----------+
```
可以看到语句中 a 表(bus_jijin_trade_record)的条件 id >= 177045000，和 updated_at > date_sub(now(), interval 48 hour)上，这两个列分别都有索引，但是 TiDB 还是选择了全表扫描。