3.DML语句

DML：INDERT，DELETE，UPDATE
INSERT
一次插入一行或多行数据，语法如下：

INSERT [LOW_PRIORITY | DELAYED | HIGH_PRIORITY] [IGNORE] [INTO] tbl_name [(col_name,...)] 
{VALUES |VALUE} ({expr |DEFAULT},...),(...),... [ ON DUPLICATE KEY UPDATE 如果重复更新之 col_name=expr [, col_name=expr] ...] 
简化写法：
INSERT tbl_name [(col1,...)] VALUES (val1,...),(val2,...)

INSERT [LOW_PRIORITY | DELAYED | HIGH_PRIORITY] [IGNORE] [INTO] tbl_name SET 
col_name={expr |DEFAULT},... [ ON DUPLICATE KEY UPDATE col_name=expr [,col_name=expr]...]

INSERT [LOW_PRIORITY | DELAYED | HIGH_PRIORITY] [IGNORE] [INTO] tbl_name SELECT
[ ON DUPLICATE KEY UPDATE col_name=expr [,col_name=expr]...]

UPDATE

UPDATE [LOW_PRIORITY] [IGNORE] table_reference SET col_name1={expr1|DEFAULT} 
[,col_name2={expr2|DEFAULT}]... [WHERE where_condition] [ORDER BY ...] [LIMIT row_count]
注意：
  一定要有限制条件，否则将修改所有行的指定字段
   显示条件：
    WHERE，LIMIT
mysql 选项：-U|--safe-updates| --i-am-a-dummy

DELETE

DELETE [LOW_PRIORITY] [QUICK] [IGNORE] FROM tbl_name [WHERE where_condition] 
[ORDER BY ...] [LIMIT row_count]
可先排序在指定删除的行数
注意：一定要有限制条件，否则将清空表中的所有数据
  限制条件：
    WHERE
    LIMIT
TRUNCATE TABLE tbl_name;清空表