检查MySQL中的表是否存在，如果存在则显示警告？

CREATE TABLE IF NOT EXISTS yourTableName
(
   yourColumnName1 dataType,
   .
   .
   .
   .
   N
);

mysql> CREATE TABLE IF NOT EXISTS DemoTable
   (
   Id int
   );
Query OK, 0 rows affected, 1 warning (0.06 sec)

mysql> show warnings;

+-------+------+-------------------------------------+
| Level | Code | Message                             |
+-------+------+-------------------------------------+
| Note  | 1050 | Table 'DemoTable' already exists    |
+-------+------+-------------------------------------+
1 row in set (0.00 sec)

mysql> CREATE TABLE IF NOT EXISTS DemoTable2
   (
   Id int
   );
Query OK, 0 rows affected (0.71 sec)