sql 整理

MySQL

• LIKE
  SELECT field_name from table where LIKE '%val%';
  % (通配符)任意多个字符包含0个字符

• BETWEEN AND
  SELECT field_name FORM table where field_name BETWEEN start AND num;

• IN
  SELECT field_name FORM table WHERE field_name IN('str',...);

• DISTINCT (去重)
  SELECT DISTINCT field_name FORM table ;

• ORDER BY 排序 (ASC升序 DESC降序)
  SELECT * from tab_name where cond ORDER BY field_name;

• LENGTH (长度函数)
  SELECT LENGTH(last_name) NameLen
  FROM employees
  RDER BY NameLen DESC; # ORDER BY 支持起别名
  ORDER BY 可以支持单个字段，多个字段，表达式，函数，别名

函数

• 单行函数 concat,length,ifnull ...
• 分组函数
• 数学函数 round,ceil,floor,truncate,mod
• 日期函数 now,curdate,curtime,sto_to_date,date_format,