数据库 关键字：
为了避免在数据库表结构设计过程中使用系统保留关键字我们必须知道数据库存在哪些关键字，接下来会列出mysql、oracle、sqlserver三个数据库各自的保留关键字。
Mysql
http://dev.mysql.com/doc/refman/5.7/en/keywords.html
| ACCESSIBLE (R) | ACCOUNT[a] | ACTION |
| ADD (R) | AFTER | AGAINST |
| AGGREGATE | ALGORITHM | ALL (R) |
| ALTER (R) | ALWAYS[b] | ANALYSE |
| ANALYZE (R) | AND (R) | ANY |
| AS (R) | ASC (R) | ASCII |
| ASENSITIVE (R) | AT | AUTOEXTEND_SIZE |
| AUTO_INCREMENT | AVG | AVG_ROW_LENGTH |
| BACKUP | BEFORE (R) | BEGIN |
| BETWEEN (R) | BIGINT (R) | BINARY (R) |
| BINLOG | BIT | BLOB (R) |
| BLOCK | BOOL | BOOLEAN |
| BOTH (R) | BTREE | BY (R) |
| BYTE | CACHE | CALL (R) |
| CASCADE (R) | CASCADED | CASE (R) |
| CATALOG_NAME | CHAIN | CHANGE (R) |
| CHANGED | CHANNEL[c] | CHAR (R) |
| CHARACTER (R) | CHARSET | CHECK (R) |
| CHECKSUM | CIPHER | CLASS_ORIGIN |
| CLIENT | CLOSE | COALESCE |
| CODE | COLLATE (R) | COLLATION |
| COLUMN (R) | COLUMNS | COLUMN_FORMAT |
| COLUMN_NAME | COMMENT | COMMIT |
| COMMITTED | COMPACT | COMPLETION |
| COMPRESSED | COMPRESSION[d] | CONCURRENT |
| CONDITION (R) | CONNECTION | CONSISTENT |
| CONSTRAINT (R) | CONSTRAINT_CATALOG | CONSTRAINT_NAME |
| CONSTRAINT_SCHEMA | CONTAINS | CONTEXT |
| CONTINUE (R) | CONVERT (R) | CPU |
| CREATE (R) | CROSS (R) | CUBE |
| CURRENT | CURRENT_DATE (R) | CURRENT_TIME (R) |
| CURRENT_TIMESTAMP (R) | CURRENT_USER (R) | CURSOR (R) |
| CURSOR_NAME | DATA | DATABASE (R) |
| DATABASES (R) | DATAFILE | DATE |
| DATETIME | DAY | DAY_HOUR (R) |
| DAY_MICROSECOND (R) | DAY_MINUTE (R) | DAY_SECOND (R) |
| DEALLOCATE | DEC (R) | DECIMAL (R) |
| DECLARE (R) | DEFAULT (R) | DEFAULT_AUTH |
