# Column Properties
+ Column properties include the following:
  + `NULL`, `DEFAULT`, `NOT NULL`, `AUTO_INCREMENT`, `AUTO_RANDOM`  
+ Examples:
```
tidb> CREATE TABLE test.dropme (
   ->   id BIGINT PRIMARY KEY AUTO_RANDOM,
   ->   id2 BIGINT ~!@auto_increment@!~,
   ->   isvalid ENUM('T', 'F') NOT NULL DEFAULT 'F'
   ->   );
~!@ERROR 1075 (42000)@!~: Incorrect table definition; there can be only one auto column and it must be defined as a key

tidb> CREATE TABLE test.dropme (
   ->   id BIGINT ~!@PRIMARY KEY AUTO_RANDOM@!~,
   ->   id2 BIGINT NOT NULL,
   ->   isvalid ENUM('T', 'F') NOT NULL DEFAULT 'F'
   ->   );
Query OK, 0 rows affected, 1 warning (0.52 sec)
```
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TiDB supports the following table options and ignores other table option parameters, such as `AVG_ROW_LENGTH`, `CHECKSUM`, `COMPRESSION`, `CONNECTION`, `DELAY_KEY_WRITE`, `ENGINE`, `KEY_BLOCK_SIZE`, `MAX_ROWS`, `MIN_ROWS`, `ROW_FORMAT`, and `STATS_PERSISTENT`.

`AUTO_INCREMENT`: The initial value of the self-increment column, for example, `AUTO_INCREMENT = 5`.

`SHARD_ROW_ID_BITS`: Number of bits used to set the number of shards for implicit `_tidb_rowid`, for example, `SHARD_ROW_ID_BITS = 4`

`PRE_SPLIT_REGIONS`: To split `2^(PRE_SPLIT_REGIONS)` regions evenly in advance when creating a table, for example, `PRE_SPLIT_REGIONS = 4`

`AUTO_ID_CACHE`: To specify the size of the cache to hold a batch of auto generated IDs in a TiDB instance. By default, `AUTO_ID_CACHE` is set to 200.

`AUTO_RANDOM_BASE`: To specify the initial value of the auto increment part for `AUTO_RANDOM`, which can be considered a part of the internal interface.

`CHARACTER SET`: To specify the character set used by this table, for example, `CHARACTER SET = 'utf8mb4'`.

`COLLATE`: To specify the character set collation used by the table, for example, `COLLATE = 'utf8mb4_bin'`.

`COMMENT`: To contain the comment information, for example, `COMMENT = 'comment info'`.