docs: Add TQL value aliasing documentation for EVAL command

docs/reference/sql/tql.md

@@ -12,7 +12,7 @@ The `TQL` keyword executes TQL language in SQL. The TQL is Time-Series Query Lan
 ### Syntax
 
 ```sql
-TQL [EVAL | EVALUATE] (start, end, step) expr
+TQL [EVAL | EVALUATE] (start, end, step) expr [AS alias]
 ```
 
 The `start`, `end` and `step` are the query parameters just like [Prometheus Query API](https://prometheus.io/docs/prometheus/latest/querying/api/):
@@ -23,6 +23,8 @@ The `start`, `end` and `step` are the query parameters just like [Prometheus Que
 
 The `expr` is the TQL expression query string.
 
+The optional `AS alias` clause allows you to provide an alias for the query result. This is useful for giving meaningful names to the output columns.
+
 ### Examples
 
 Return the per-second rate for all time series with the `http_requests_total` metric name, as measured over the last 5 minutes:
@@ -33,6 +35,14 @@ TQL eval (1677057993, 1677058993, '1m') rate(prometheus_http_requests_total{job=
 
 will get a result just like other normal SQL queries.
 
+You can also use value aliasing to give a meaningful name to your query result:
+
+```sql
+TQL eval (0, 10, '5s') {__name__="test"} AS test_series;
+```
+
+This will return the results with the column named `test_series` instead of the default column name.
+
 ## EXPLAIN
 
 `EXPLAIN` displays both the logical plan and execution plan for a given PromQL query. The syntax is as follows:

i18n/zh/docusaurus-plugin-content-docs/current/reference/sql/tql.md

@@ -12,7 +12,7 @@ description: 介绍了 `TQL` 关键字及其在 GreptimeDB 中的用法，包括
 ### Syntax
 
 ```sql
-TQL [EVAL | EVALUATE] (start, end, step) expr
+TQL [EVAL | EVALUATE] (start, end, step) expr [AS alias]
 ```
 
 `start`, `end` 和 `step` 是查询参数，就像 [Prometheus Query API](https://prometheus.io/docs/prometheus/latest/querying/api/) 一样：
@@ -23,6 +23,8 @@ TQL [EVAL | EVALUATE] (start, end, step) expr
 
 `expr` 是 TQL 表达式查询字符串。
 
+可选的 `AS alias` 子句允许你为查询结果提供别名。这有助于为输出列提供有意义的名称。
+
 ### 示例
 
 返回过去 5 分钟内 `http_requests_total` 指标的所有时间序列的每秒值：
@@ -33,6 +35,14 @@ TQL eval (1677057993, 1677058993, '1m') rate(prometheus_http_requests_total{job=
 
 其查询结果和 SQL 查询结果类似。
 
+你也可以使用值别名为查询结果提供有意义的名称：
+
+```sql
+TQL eval (0, 10, '5s') {__name__="test"} AS test_series;
+```
+
+这将返回列名为 `test_series` 而不是默认列名的结果。
+
 ## EXPLAIN
 
 `EXPLAIN` 展示特定 PromQL 查询的逻辑计划和执行计划，其语法如下：

i18n/zh/docusaurus-plugin-content-docs/version-0.17/reference/sql/tql.md

@@ -12,7 +12,7 @@ description: 介绍了 `TQL` 关键字及其在 GreptimeDB 中的用法，包括
 ### Syntax
 
 ```sql
-TQL [EVAL | EVALUATE] (start, end, step) expr
+TQL [EVAL | EVALUATE] (start, end, step) expr [AS alias]
 ```
 
 `start`, `end` 和 `step` 是查询参数，就像 [Prometheus Query API](https://prometheus.io/docs/prometheus/latest/querying/api/) 一样：
@@ -23,6 +23,8 @@ TQL [EVAL | EVALUATE] (start, end, step) expr
 
 `expr` 是 TQL 表达式查询字符串。
 
+可选的 `AS alias` 子句允许你为查询结果提供别名。这有助于为输出列提供有意义的名称。
+
 ### 示例
 
 返回过去 5 分钟内 `http_requests_total` 指标的所有时间序列的每秒值：
@@ -33,6 +35,14 @@ TQL eval (1677057993, 1677058993, '1m') rate(prometheus_http_requests_total{job=
 
 其查询结果和 SQL 查询结果类似。
 
+你也可以使用值别名为查询结果提供有意义的名称：
+
+```sql
+TQL eval (0, 10, '5s') {__name__="test"} AS test_series;
+```
+
+这将返回列名为 `test_series` 而不是默认列名的结果。
+
 ## EXPLAIN
 
 `EXPLAIN` 展示特定 PromQL 查询的逻辑计划和执行计划，其语法如下：

versioned_docs/version-0.17/reference/sql/tql.md

@@ -12,7 +12,7 @@ The `TQL` keyword executes TQL language in SQL. The TQL is Time-Series Query Lan
 ### Syntax
 
 ```sql
-TQL [EVAL | EVALUATE] (start, end, step) expr
+TQL [EVAL | EVALUATE] (start, end, step) expr [AS alias]
 ```
 
 The `start`, `end` and `step` are the query parameters just like [Prometheus Query API](https://prometheus.io/docs/prometheus/latest/querying/api/):
@@ -23,6 +23,8 @@ The `start`, `end` and `step` are the query parameters just like [Prometheus Que
 
 The `expr` is the TQL expression query string.
 
+The optional `AS alias` clause allows you to provide an alias for the query result. This is useful for giving meaningful names to the output columns.
+
 ### Examples
 
 Return the per-second rate for all time series with the `http_requests_total` metric name, as measured over the last 5 minutes:
@@ -33,6 +35,14 @@ TQL eval (1677057993, 1677058993, '1m') rate(prometheus_http_requests_total{job=
 
 will get a result just like other normal SQL queries.
 
+You can also use value aliasing to give a meaningful name to your query result:
+
+```sql
+TQL eval (0, 10, '5s') {__name__="test"} AS test_series;
+```
+
+This will return the results with the column named `test_series` instead of the default column name.
+
 ## EXPLAIN
 
 `EXPLAIN` displays both the logical plan and execution plan for a given PromQL query. The syntax is as follows: