91 lines
4.4 KiB
Markdown
91 lines
4.4 KiB
Markdown
---
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title: Keywords
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---
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There are about 200 keywords reserved by TDengine, they can't be used as the name of database, STable or table with either upper case, lower case or mixed case.
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**Keywords List**
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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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| _C0 | _QSTART | _QSTOP | _QDURATION | _WSTART |
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| _WSTOP | _WDURATION | _ROWTS |
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## Explanations
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### TBNAME
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`TBNAME` can be considered as a special tag, which represents the name of the subtable, in a STable.
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Get the table name and tag values of all subtables in a STable.
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```mysql
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SELECT TBNAME, location FROM meters;
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```
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Count the number of subtables in a STable.
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```mysql
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SELECT COUNT(TBNAME) FROM meters;
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```
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Only filter on TAGS can be used in WHERE clause in the above two query statements.
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```mysql
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taos> SELECT TBNAME, location FROM meters;
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tbname | location |
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==================================================================
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d1004 | California.SanFrancisco |
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d1003 | California.SanFrancisco |
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d1002 | California.LosAngeles |
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d1001 | California.LosAngeles |
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Query OK, 4 row(s) in set (0.000881s)
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taos> SELECT COUNT(tbname) FROM meters WHERE groupId > 2;
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count(tbname) |
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========================
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2 |
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Query OK, 1 row(s) in set (0.001091s)
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```
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### _QSTART/_QSTOP/_QDURATION
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The start, stop and duration of a query time window.
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### _WSTART/_WSTOP/_WDURATION
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The start, stop and duration of aggegate query by time window, like interval, session window, state window.
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### _c0/_ROWTS
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_c0 is equal to _ROWTS, it means the first column of a table or STable.
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