mysql学习笔记(6-DML命令)

DML：INSERT， DELETE， UPDATE， SELECT

INSERT INTO：
INSERT [INTO] tbl_name [(col1,...)] {VALUES|VALUE} (val1, ...),(...),...
注意：
字符型：引号；
数值型：不能用引号；

SELECT：
(1) SELECT * FROM tbl_name;
(2) SELECT col1, col2, ... FROM tbl_name;
显示时，字段可以显示为别名；
col_name AS col_alias
(3) SELECT col1, ... FROM tbl_name WHERE clause;
WHERE clause：用于指明挑选条件；
col_name 操作符 value：
age > 30;

操作符(1) ：
>, <, >=, <=, ==, !=

组合条件：
and
or
not

操作符(2) ：
BETWEEN ... AND ...
LIKE 'PATTERN'
通配符：
%：任意长度的任意字符；
_：任意单个字符；
RLIKE 'PATTERN'
正则表达式对字符串做模式匹配；
IS NULL
IS NOT NULL
(4) SELECT col1, ... FROM tbl_name [WHERE clause] ORDER BY col_name, col_name2, ... [ASC|DESC];
ASC: 升序；
DESC： 降序；

DELETE：
DELETE FROM tbl_name [WHERE where_condition] [ORDER BY ...] [LIMIT row_count] (1) DELETE FROM tbl_name WHERE where_condition
(2) DELETE FROM tbl_name [ORDER BY ...] [LIMIT row_count]

UPDATE：
UPDATE [LOW_PRIORITY] [IGNORE] table_reference SET col_name1=value1 [, col_name2=value2] ... [WHERE where_condition] [ORDER BY ...] [LIMIT row_count]