From 7e541a5f3ffff8b109e00d838f1138b1214d4b7c Mon Sep 17 00:00:00 2001 From: shenglian zhou Date: Tue, 19 Dec 2023 08:49:56 +0800 Subject: [PATCH 1/2] Revert "fix: remove tags keyword from document" This reverts commit 83e2e0dffd06af1c46b70e47963a8fdb34e36e27. --- docs/en/12-taos-sql/06-select.md | 10 +++++++++- docs/zh/12-taos-sql/06-select.md | 12 +++++++++++- 2 files changed, 20 insertions(+), 2 deletions(-) diff --git a/docs/en/12-taos-sql/06-select.md b/docs/en/12-taos-sql/06-select.md index f1e19a5449..f229f0d77b 100755 --- a/docs/en/12-taos-sql/06-select.md +++ b/docs/en/12-taos-sql/06-select.md @@ -9,7 +9,7 @@ description: This document describes how to query data in TDengine. ```sql SELECT {DATABASE() | CLIENT_VERSION() | SERVER_VERSION() | SERVER_STATUS() | NOW() | TODAY() | TIMEZONE() | CURRENT_USER() | USER() } -SELECT [hints] [DISTINCT] select_list +SELECT [hints] [DISTINCT] [TAGS] select_list from_clause [WHERE condition] [partition_by_clause] @@ -227,6 +227,14 @@ The \_IROWTS pseudocolumn can only be used with INTERP function. This pseudocolu select _irowts, interp(current) from meters range('2020-01-01 10:00:00', '2020-01-01 10:30:00') every(1s) fill(linear); ``` +### TAGS Query + +The TAGS keyword returns only tag columns from all child tables when only tag columns are specified. One row containing tag columns is returned for each child table. + +```sql +SELECT TAGS tag_name [, tag_name ...] FROM stb_name +``` + ## Query Objects `FROM` can be followed by a number of tables or super tables, or can be followed by a sub-query. diff --git a/docs/zh/12-taos-sql/06-select.md b/docs/zh/12-taos-sql/06-select.md index 04508ceede..1e11019ab9 100755 --- a/docs/zh/12-taos-sql/06-select.md +++ b/docs/zh/12-taos-sql/06-select.md @@ -9,7 +9,7 @@ description: 查询数据的详细语法 ```sql SELECT {DATABASE() | CLIENT_VERSION() | SERVER_VERSION() | SERVER_STATUS() | NOW() | TODAY() | TIMEZONE() | CURRENT_USER() | USER() } -SELECT [hints] [DISTINCT] select_list +SELECT [hints] [DISTINCT] [TAGS] select_list from_clause [WHERE condition] [partition_by_clause] @@ -162,6 +162,16 @@ SELECT DISTINCT col_name [, col_name ...] FROM tb_name; ::: +### 标签查询 + +当查询的列只有标签列时，`TAGS` 关键字可以指定返回所有子表的标签列。每个子表只返回一行标签列。 + +返回所有子表的标签列： + +```sql +SELECT TAGS tag_name [, tag_name ...] FROM stb_name +``` + ### 结果集列名 `SELECT`子句中，如果不指定返回结果集合的列名，结果集列名称默认使用`SELECT`子句中的表达式名称作为列名称。此外，用户可使用`AS`来重命名返回结果集合中列的名称。例如： From 713d29d92aa5cb03e207d5e704bd5ac23fd22fd0 Mon Sep 17 00:00:00 2001 From: shenglian zhou Date: Tue, 19 Dec 2023 08:53:45 +0800 Subject: [PATCH 2/2] doc: select tags to retrieve tags --- docs/en/12-taos-sql/06-select.md | 2 +- docs/zh/12-taos-sql/06-select.md | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/docs/en/12-taos-sql/06-select.md b/docs/en/12-taos-sql/06-select.md index f229f0d77b..82acc97491 100755 --- a/docs/en/12-taos-sql/06-select.md +++ b/docs/en/12-taos-sql/06-select.md @@ -182,7 +182,7 @@ The TBNAME pseudocolumn in a supertable contains the names of subtables within t The following SQL statement returns all unique subtable names and locations within the meters supertable: ```mysql -SELECT DISTINCT TBNAME, location FROM meters; +SELECT TAGS TBNAME, location FROM meters; ``` Use the `INS_TAGS` system table in `INFORMATION_SCHEMA` to query the information for subtables in a supertable. For example, the following statement returns the name and tag values for each subtable in the `meters` supertable. diff --git a/docs/zh/12-taos-sql/06-select.md b/docs/zh/12-taos-sql/06-select.md index 1e11019ab9..7f346bd36e 100755 --- a/docs/zh/12-taos-sql/06-select.md +++ b/docs/zh/12-taos-sql/06-select.md @@ -192,7 +192,7 @@ taos> SELECT ts, ts AS primary_key_ts FROM d1001; 获取一个超级表所有的子表名及相关的标签信息： ```mysql -SELECT DISTINCT TBNAME, location FROM meters; +SELECT TAGS TBNAME, location FROM meters; ``` 建议用户使用 INFORMATION_SCHEMA 下的 INS_TAGS 系统表来查询超级表的子表标签信息，例如获取超级表 meters 所有的子表名和标签值：