- "[]" square brackets:可选项
DROP TABLE [IF EXISTS] tbl_name
- "|"vertical bars:选择其中的一个
TRIM([[BOTH | LEADING | TRAILING] [remstr] FROM] str)
- "()"braces:表示必须选项
{DESCRIBE | DESC} tbl_name [col_name | wild]
- "..."ellipisis :省略部分,或者重复
SELECT ... INTO OUTFILE #省略
RESET reset_option [,reset_option] ... #重复可选项