Merge pull request #6658 from taosdata/docs/Update-Latest-Feature
Docs/update latest feature
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Elias Soong
GitHub
commit
c9f832f466
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@ -465,43 +465,44 @@ TDengine的所有可执行文件默认存放在 _/usr/local/taos/bin_ 目录下
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目前 TDengine 有将近 200 个内部保留关键字，这些关键字无论大小写均不可以用作库名、表名、STable 名、数据列名及标签列名等。这些关键字列表如下：
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| 关键字列表 | | | | |
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| ---------- | ----------- | ------------ | ---------- | --------- |
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| ABLOCKS | CONNECTIONS | HAVING | MODULES | SMALLINT |
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| ABORT | COPY | ID | NCHAR | SPREAD |
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| ACCOUNT | COUNT | IF | NE | STABLE |
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| ACCOUNTS | CREATE | IGNORE | NONE | STABLES |
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| ADD | CTIME | IMMEDIATE | NOT | STAR |
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| AFTER | DATABASE | IMPORT | NOTNULL | STATEMENT |
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| ALL | DATABASES | IN | NOW | STDDEV |
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| ALTER | DAYS | INITIALLY | OF | STREAM |
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| AND | DEFERRED | INSERT | OFFSET | STREAMS |
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| AS | DELIMITERS | INSTEAD | OR | STRING |
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| ASC | DESC | INTEGER | ORDER | SUM |
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| ATTACH | DESCRIBE | INTERVAL | PASS | TABLE |
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| AVG | DETACH | INTO | PERCENTILE | TABLES |
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| BEFORE | DIFF | IP | PLUS | TAG |
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| BEGIN | DISTINCT | IS | PRAGMA | TAGS |
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| BETWEEN | DIVIDE | ISNULL | PREV | TBLOCKS |
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| BIGINT | DNODE | JOIN | PRIVILEGE | TBNAME |
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| BINARY | DNODES | KEEP | QUERIES | TIMES |
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| BITAND | DOT | KEY | QUERY | TIMESTAMP |
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| BITNOT | DOUBLE | KILL | RAISE | TINYINT |
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| BITOR | DROP | LAST | REM | TOP |
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| BOOL | EACH | LE | REPLACE | TOPIC |
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| BOTTOM | END | LEASTSQUARES | REPLICA | TRIGGER |
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| BY | EQ | LIKE | RESET | UMINUS |
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| CACHE | EXISTS | LIMIT | RESTRICT | UNION |
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| CASCADE | EXPLAIN | LINEAR | ROW | UPLUS |
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| CHANGE | FAIL | LOCAL | ROWS | USE |
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| CLOG | FILL | LP | RP | USER |
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| CLUSTER | FIRST | LSHIFT | RSHIFT | USERS |
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| COLON | FLOAT | LT | SCORES | USING |
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| COLUMN | FOR | MATCH | SELECT | VALUES |
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| COMMA | FROM | MAX | SEMI | VARIABLE |
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| COMP | GE | METRIC | SET | VGROUPS |
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| CONCAT | GLOB | METRICS | SHOW | VIEW |
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| CONFIGS | GRANTS | MIN | SLASH | WAVG |
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| CONFLICT | GROUP | MINUS | SLIDING | WHERE |
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| CONNECTION | GT | MNODES | SLIMIT | |
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| 关键字列表 | | | | |
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| ------------ | ------------ | ------------ | ------------ | ------------ |
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| ABORT | CREATE | IGNORE | NULL | STAR |
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| ACCOUNT | CTIME | IMMEDIATE | OF | STATE |
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| ACCOUNTS | DATABASE | IMPORT | OFFSET | STATEMENT |
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| ADD | DATABASES | IN | OR | STATE_WINDOW |
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| AFTER | DAYS | INITIALLY | ORDER | STORAGE |
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| ALL | DBS | INSERT | PARTITIONS | STREAM |
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| ALTER | DEFERRED | INSTEAD | PASS | STREAMS |
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| AND | DELIMITERS | INT | PLUS | STRING |
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| AS | DESC | INTEGER | PPS | SYNCDB |
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| ASC | DESCRIBE | INTERVAL | PRECISION | TABLE |
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| ATTACH | DETACH | INTO | PREV | TABLES |
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| BEFORE | DISTINCT | IS | PRIVILEGE | TAG |
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| BEGIN | DIVIDE | ISNULL | QTIME | TAGS |
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| BETWEEN | DNODE | JOIN | QUERIES | TBNAME |
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| BIGINT | DNODES | KEEP | QUERY | TIMES |
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| BINARY | DOT | KEY | QUORUM | TIMESTAMP |
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| BITAND | DOUBLE | KILL | RAISE | TINYINT |
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| BITNOT | DROP | LE | REM | TOPIC |
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| BITOR | EACH | LIKE | REPLACE | TOPICS |
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| BLOCKS | END | LIMIT | REPLICA | TRIGGER |
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| BOOL | EQ | LINEAR | RESET | TSERIES |
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| BY | EXISTS | LOCAL | RESTRICT | UMINUS |
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| CACHE | EXPLAIN | LP | ROW | UNION |
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| CACHELAST | FAIL | LSHIFT | RP | UNSIGNED |
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| CASCADE | FILE | LT | RSHIFT | UPDATE |
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| CHANGE | FILL | MATCH | SCORES | UPLUS |
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| CLUSTER | FLOAT | MAXROWS | SELECT | USE |
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| COLON | FOR | MINROWS | SEMI | USER |
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| COLUMN | FROM | MINUS | SESSION | USERS |
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| COMMA | FSYNC | MNODES | SET | USING |
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| COMP | GE | MODIFY | SHOW | VALUES |
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| COMPACT | GLOB | MODULES | SLASH | VARIABLE |
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| CONCAT | GRANTS | NCHAR | SLIDING | VARIABLES |
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| CONFLICT | GROUP | NE | SLIMIT | VGROUPS |
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| CONNECTION | GT | NONE | SMALLINT | VIEW |
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| CONNECTIONS | HAVING | NOT | SOFFSET | VNODES |
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| CONNS | ID | NOTNULL | STABLE | WAL |
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| COPY | IF | NOW | STABLES | WHERE |
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@ -89,13 +89,13 @@ TDengine 缺省的时间戳是毫秒精度，但通过在 CREATE DATABASE 时传
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```mysql
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USE db_name;
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```
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使用/切换数据库
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使用/切换数据库（在 RESTful 连接方式下无效）。
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- **删除数据库**
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```mysql
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DROP DATABASE [IF EXISTS] db_name;
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```
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删除数据库。所包含的全部数据表将被删除，谨慎使用
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删除数据库。指定 Database 所包含的全部数据表将被删除，谨慎使用！
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- **修改数据库参数**
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```mysql
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@ -703,22 +703,24 @@ Query OK, 1 row(s) in set (0.001091s)
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### 支持的条件过滤操作
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| **Operation** | **Note** | **Applicable Data Types** |
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| --------------- | ----------------------------- | ------------------------------------- |
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| > | larger than | **`timestamp`** and all numeric types |
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| < | smaller than | **`timestamp`** and all numeric types |
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| >= | larger than or equal to | **`timestamp`** and all numeric types |
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| <= | smaller than or equal to | **`timestamp`** and all numeric types |
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| = | equal to | all types |
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| <> | not equal to | all types |
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| between and | within a certain range | **`timestamp`** and all numeric types |
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| % | match with any char sequences | **`binary`** **`nchar`** |
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| _ | match with a single char | **`binary`** **`nchar`** |
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| **Operation** | **Note** | **Applicable Data Types** |
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| --------------- | ----------------------------- | ----------------------------------------- |
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| > | larger than | **`timestamp`** and all numeric types |
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| < | smaller than | **`timestamp`** and all numeric types |
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| >= | larger than or equal to | **`timestamp`** and all numeric types |
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| <= | smaller than or equal to | **`timestamp`** and all numeric types |
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| = | equal to | all types |
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| <> | not equal to | all types |
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| between and | within a certain range | **`timestamp`** and all numeric types |
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| in | matches any value in a set | all types except first column `timestamp` |
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| % | match with any char sequences | **`binary`** **`nchar`** |
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| _ | match with a single char | **`binary`** **`nchar`** |
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1. <> 算子也可以写为 != ，请注意，这个算子不能用于数据表第一列的 timestamp 字段。
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2. 同时进行多个字段的范围过滤，需要使用关键词 AND 来连接不同的查询条件，暂不支持 OR 连接的不同列之间的查询过滤条件。
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3. 针对单一字段的过滤，如果是时间过滤条件，则一条语句中只支持设定一个；但针对其他的（普通）列或标签列，则可以使用 `OR` 关键字进行组合条件的查询过滤。例如：((value > 20 AND value < 30) OR (value < 12)) 。
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4. 从 2.0.17 版本开始，条件过滤开始支持 BETWEEN AND 语法，例如 `WHERE col2 BETWEEN 1.5 AND 3.25` 表示查询条件为“1.5 ≤ col2 ≤ 3.25”。
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3. 针对单一字段的过滤，如果是时间过滤条件，则一条语句中只支持设定一个；但针对其他的（普通）列或标签列，则可以使用 `OR` 关键字进行组合条件的查询过滤。例如： `((value > 20 AND value < 30) OR (value < 12))`。
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4. 从 2.0.17.0 版本开始，条件过滤开始支持 BETWEEN AND 语法，例如 `WHERE col2 BETWEEN 1.5 AND 3.25` 表示查询条件为“1.5 ≤ col2 ≤ 3.25”。
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5. 从 2.1.4.0 版本开始，条件过滤开始支持 IN 算子，例如 `WHERE city IN ('Beijing', 'Shanghai')`。说明：BOOL 类型写作 `{true, false}` 或 `{0, 1}` 均可，但不能写作 0、1 之外的整数；FLOAT 和 DOUBLE 类型会受到浮点数精度影响，集合内的值在精度范围内认为和数据行的值完全相等才能匹配成功。<!-- REPLACE_OPEN_TO_ENTERPRISE__IN_OPERATOR_AND_UNSIGNED_INTEGER -->
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<!--
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<a class="anchor" id="having"></a>
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