关键字和保留字
关键字在 SQL 中有特殊的意义， 例如 SELECT，UPDATE，DELETE，在作为表名跟函数名的时候，需要特殊对待，例如作为表名，保留字需要被反引号包住：
mysql> CREATE TABLE select (a INT);
ERROR 1105 (HY000): line 0 column 19 near " (a INT)" (total length 27)
mysql> CREATE TABLE `select` (a INT);
Query OK, 0 rows affected (0.09 sec)
BEGIN 和 END 是关键字， 但不是保留字，所以不需要反引号：
mysql> CREATE TABLE `select` (BEGIN int, END int);
Query OK, 0 rows affected (0.09 sec)
有一种特殊情况， 如果使用了限定符 .，那么也不需要用反引号：
mysql> CREATE TABLE test.select (BEGIN int, END int);
Query OK, 0 rows affected (0.08 sec)
下表列出了在 TiDB 中的关键字跟保留字，保留字用 (R) 来标识：
| ACTION | ADD(R) | ADDDATE | |
|---|---|---|---|
| ADMIN | AFTER | ALL(R) | |
| ALTER(R) | ALWAYS | ANALYZE(R) | |
| AND(R) | ANY | AS(R) | |
| ASC(R) | ASCII | AUTO_INCREMENT | |
| AVG | AVG_ROW_LENGTH | BEGIN | |
| BETWEEN(R) | BIGINT(R) | BINARY(R) | |
| BINLOG | BIT | BIT_XOR | |
| BLOB(R) | BOOL | BOOLEAN | |
| BOTH(R) | BTREE | BY(R) | |
| BYTE | CASCADE(R) | CASE(R) | |
| CAST | CHANGE(R) | CHAR(R) | |
| CHARACTER(R) | CHARSET | CHECK(R) | |
| CHECKSUM | COALESCE | COLLATE(R) | |
| COLLATION | COLUMN(R) | COLUMNS | |
| COMMENT | COMMIT | COMMITTED | |
| COMPACT | COMPRESSED | COMPRESSION | |
| CONNECTION | CONSISTENT | CONSTRAINT(R) | |
| CONVERT(R) | COUNT | CREATE(R) | |
| CROSS(R) | CURRENT_DATE(R) | CURRENT_TIME(R) | |
| CURRENT_TIMESTAMP(R) | CURRENT_USER(R) | CURTIME | |
| DATA | DATABASE(R) | DATABASES(R) | |
| DATE | DATE_ADD | DATE_SUB | |
| DATETIME | DAY | DAY_HOUR(R) | |
| DAY_MICROSECOND(R) | DAY_MINUTE(R) | DAY_SECOND(R) | |
| DDL | DEALLOCATE | DEC | |
| DECIMAL(R) | DEFAULT(R) | DELAY_KEY_WRITE | |
| DELAYED(R) | DELETE(R) | DESC(R) | |
| DESCRIBE(R) | DISABLE | DISTINCT(R) | |
| DISTINCTROW(R) | DIV(R) | DO | |
| DOUBLE(R) | DROP(R) | DUAL(R) | |
| DUPLICATE | DYNAMIC | ELSE(R) | |
| ENABLE | ENCLOSED | END | |
| ENGINE | ENGINES | ENUM | |
| ESCAPE | ESCAPED | EVENTS | |
| EXCLUSIVE | EXECUTE | EXISTS | |
| EXPLAIN(R) | EXTRACT | FALSE(R) | |
| FIELDS | FIRST | FIXED | |
| FLOAT(R) | FLUSH | FOR(R) | |
| FORCE(R) | FOREIGN(R) | FORMAT | |
| FROM(R) | FULL | FULLTEXT(R) | |
| FUNCTION | GENERATED(R) | GET_FORMAT | |
| GLOBAL | GRANT(R) | GRANTS | |
| GROUP(R) | GROUP_CONCAT | HASH | |
| HAVING(R) | HIGH_PRIORITY(R) | HOUR | |
| HOUR_MICROSECOND(R) | HOUR_MINUTE(R) | HOUR_SECOND(R) | |
| IDENTIFIED | IF(R) | IGNORE(R) | |
| IN(R) | INDEX(R) | INDEXES | |
| INFILE(R) | INNER(R) | INSERT(R) | |
| INT(R) | INTEGER(R) | INTERVAL(R) | |
| INTO(R) | IS(R) | ISOLATION | |
| JOBS | JOIN(R) | JSON | |
| KEY(R) | KEY_BLOCK_SIZE | KEYS(R) | |
| KILL(R) | LEADING(R) | LEFT(R) | |
| LESS | LEVEL | LIKE(R) | |
| LIMIT(R) | LINES(R) | LOAD(R) | |
| LOCAL | LOCALTIME(R) | LOCALTIMESTAMP(R) | |
| LOCK(R) | LONGBLOB(R) | LONGTEXT(R) | |
| LOW_PRIORITY(R) | MAX | MAX_ROWS | |
| MAXVALUE(R) | MEDIUMBLOB(R) | MEDIUMINT(R) | |
| MEDIUMTEXT(R) | MICROSECOND | MIN | |
| MIN_ROWS | MINUTE | MINUTE_MICROSECOND(R) | |
| MINUTE_SECOND(R) | MIN | MIN_ROWS | |
| MINUTE | MINUTE_MICROSECOND | MINUTE_SECOND | |
| MOD(R) | MODE | MODIRY | |
| MONTH | NAMES | NATIONAL | |
| NATURAL(R) | NO | NO_WRITE_TO_BINLOG(R) | |
| NONE | NOT(R) | NOW | |
| NULL(R) | NUMERIC(R) | NVARCHAR(R) | |
| OFFSET | ON(R) | ONLY | |
| OPTION(R) | OR(R) | ORDER(R) | |
| OUTER(R) | PARTITION(R) | PARTITIONS | |
| PASSWORD | PLUGINS | POSITION | |
| PRECISION(R) | PREPARE | PRIMARY(R) | |
| PRIVILEGES | PROCEDURE(R) | PROCESS | |
| PROCESSLIST | QUARTER | QUERY | |
| QUICK | RANGE(R) | READ(R) | |
| REAL(R) | REDUNDANT | REFERENCES(R) | |
| REGEXP(R) | RENAME(R) | REPEAT(R) | |
| REPEATABLE | REPLACE(R) | RESTRICT(R) | |
| REVERSE | REVOKE(R) | RIGHT(R) | |
| RLIKE(R) | ROLLBACK | ROW | |
| ROW_COUNT | ROW_FORMAT | SCHEMA | |
| SCHEMAS | SECOND | SECOND_MICROSECOND(R) | |
| SELECT(R) | SERIALIZABLE | SESSION | |
| SET(R) | SHARE | SHARED | |
| SHOW(R) | SIGNED | SMALLINT(R) | |
| SNAPSHOT | SOME | SQL_CACHE | |
| SQL_CALC_FOUND_ROWS(R) | SQL_NO_CACHE | START | |
| STARTING(R) | STATS | STATS_BUCKETS | |
| STATS_HISTOGRAMS | STATS_META | STATS_PERSISTENT | |
| STATUS | STORED(R) | SUBDATE | |
| SUBSTR | SUBSTRING | SUM | |
| SUPER | TABLE(R) | TABLES | |
| TERMINATED(R) | TEXT | THAN | |
| THEN(R) | TIDB | TIDB_INLJ | |
| TIDB_SMJ | TIME | TIMESTAMP | |
| TIMESTAMPADD | TIMESTAMPDIFF | TINYBLOB(R) | |
| TINYINT(R) | TINYTEXT(R) | TO(R) | |
| TRAILING(R) | TRANSACTION | TRIGGER(R) | |
| TRIGGERS | TRIM | TRUE(R) | |
| TRUNCATE | UNCOMMITTED | UNION(R) | |
| UNIQUE(R) | UNKNOWN | UNLOCK(R) | |
| UNSIGNED(R) | UPDATE(R) | USE(R) | |
| USER | USING(R) | UTC_DATE(R) | |
| UTC_TIME(R) | UTC_TIMESTAMP(R) | VALUE | |
| VALUES(R) | VARBINARY(R) | VARCHAR(R) | |
| VARIABLES | VIEW | VIRTUAL(R) | |
| WARNINGS | WEEK | WHEN(R) | |
| WHERE(R) | WITH(R) | WRITE(R) | |
| XOR(R) | YEAR | YEAR_MONTH(R) | |
| ZEROFILL(R) |
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