# [Known Issue] [planner:1054]Unknown column 'test.t2.name' in 'expression'

## Key Words

planner:1054, Unknown column in expression

## Description

创建表达式索引无法成功

```sql
use test;

CREATE TABLE `t2` (
`id` int(11) NOT NULL AUTO_INCREMENT ,
`name` varchar(30) DEFAULT NULL ,
`create_time` datetime NOT NULL ,
PRIMARY KEY (`id`) ,
KEY `idx_create_time` (`create_time`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin;

create index idx_t2_name on test.t2((lower(test.t2.name)));
```

TiDB.log 日志中存在 [planner:1054]Unknown column 'test.t2.name' in 'expression' 告警

```sql
["[ddl] run DDL job error"] [worker="worker 8, tp add index"] [error="[planner:1054]Unknown column 'test.t2.name' in 'expression'"]
```

## Root Cause

代码 [BUG 39784](https://github.com/pingcap/tidb/issues/39784)

## Diagnostic Steps

1.添加表达式索引无法成功, 可以使用以下命令查看 job 状态

```sql
admin show ddl jobs 
```

2.查看 tidb.log 日志存在告警 [planner:1054]Unknown column 'test.t2.name' in 'expression'

## Resolution

在 [PR 39822](https://github.com/pingcap/tidb/pull/39822) 中修复