随笔分类 -  MySQL

mac mysql start ERROR! The server quit without updating PID file
摘要：在mac下安装完mysql，启动时出现error： ERROR! The server quit without updating PID file (/usr/local/var/mysql/nalideMacBook-Pro.local.pid) 解决办法： 1. 查看 /usr/local/v 阅读全文
posted @ 2016-03-31 21:32 lasclocker 阅读(1930) 评论(0) 推荐(0)
MySQL必知必会(使用子查询)
摘要：SELECT cust_name, cust_contact FROM customersWHERE cust_id IN (SELECT cust_id FROM orders #单独写多个分句，最后组成一个. WHERE order_num IN (SELECT... 阅读全文
posted @ 2015-08-22 21:46 lasclocker 阅读(180) 评论(0) 推荐(0)
MySQL必知必会(数据分组,Group by和Having子句, Select子句的顺序)
摘要：SELECT vend_id, COUNT(*) AS num_prods FROM products #GROUP BY子句可以包含任意数目的列，多行NULL值将分为一组GROUP BY vend_id; #GROUP BY子句必须出现在WHERE子句之后，ORDER BY子句之前。SELECT ... 阅读全文
posted @ 2015-08-22 21:20 lasclocker 阅读(394) 评论(0) 推荐(0)
MySQL必知必会(汇总数据, 聚集函数)
摘要：SELECT AVG(prod_price) AS avg_price FROM products; #AVG只能用于单个列求平均值，如想计算多个列，必须用多个AVG()SELECT AVG(prod_price) AS avg_price FROM productsWHERE vend_id = ... 阅读全文
posted @ 2015-08-22 20:13 lasclocker 阅读(448) 评论(0) 推荐(0)
MySQL必知必会(使用函数处理数据)
摘要：#文本处理函数SELECT vend_name, Upper(vend_name) AS vend_name_upcase FROM vendorsORDER BY vend_name;SELECT cust_name, cust_contact FROM customersWHERE Sounde... 阅读全文
posted @ 2015-08-22 19:41 lasclocker 阅读(248) 评论(0) 推荐(0)
MySQL必知必会(创建计算字段(field))
摘要：#字段(field)基本上和列(column)的意思相同SELECT Concat(vend_name, ' (', vend_country, ')') FROM vendorsORDER BY vend_name; #多数DBMS使用+或||来实现拼接，MySQL则使用Concat()函数来实现... 阅读全文
posted @ 2015-08-22 17:19 lasclocker 阅读(478) 评论(0) 推荐(0)
MySQL必知必会(正则表达式)
摘要：SELECT prod_name FROM products WHERE prod_name REGEXP '1000' #检索列prod_name包含文本1000的所有行.ORDER BY prod_name;SELECT prod_name FROM products WHERE prod_na... 阅读全文
posted @ 2015-08-22 16:49 lasclocker 阅读(251) 评论(0) 推荐(0)
MySQL必知必会(通配符过滤Like，%，_)
摘要：SELECT prod_id, prod_name FROM products WHERE prod_name LIKE 'jet%'; #百分号(%)表示任何字符出现任意次数, %不能匹配值为NULL的行。SELECT prod_id, prod_name FROM products WHERE ... 阅读全文
posted @ 2015-08-22 15:59 lasclocker 阅读(514) 评论(0) 推荐(0)
MySQL必知必会(组合Where子句，Not和In操作符)
摘要：SELECT prod_id, prod_price, prod_name FROM products WHERE vend_id = 1003 AND prod_price = 10; #优先处理AND操作符SELECT prod_id, prod_price, prod_name FROM pr... 阅读全文
posted @ 2015-08-22 15:42 lasclocker 阅读(1226) 评论(0) 推荐(0)
MySQL必知必会(Select, Where子句)
摘要：SELECT prod_name, prod_price FROM products WHERE prod_price = 2.5;SELECT prod_name, prod_price FROM products WHERE prod_name = 'fuses'; #默认不区分大小写SELEC... 阅读全文
posted @ 2015-08-22 12:02 lasclocker 阅读(286) 评论(0) 推荐(0)
MySQL必知必会(Select, Order by子句)
摘要：SELECT prod_name FROM products ORDER BY prod_name;SELECT prod_id, prod_price, prod_name FROM products ORDER BY prod_price, prod_name;SELECT prod_id, p... 阅读全文
posted @ 2015-08-22 11:46 lasclocker 阅读(259) 评论(0) 推荐(0)
MySQL必知必会(Select)
摘要：SELECT prod_name FROM products;SELECT prod_id, prod_name, prod_price FROM products;SELECT * FROM products;SELECT DISTINCT vend_id FROM products;SELECT... 阅读全文
posted @ 2015-08-22 11:35 lasclocker 阅读(208) 评论(0) 推荐(0)
MySQL必知必会(Insert into)
摘要：########################### Populate customers table##########################INSERT INTO customers(cust_id, cust_name, cust_address, cust_city, cust_... 阅读全文
posted @ 2015-08-22 11:20 lasclocker 阅读(372) 评论(0) 推荐(0)
MySQL必知必会(Create, Alter)
摘要：CREATE DATABASE mysql_crash_course_db;USE mysql_crash_course_db;CREATE TABLE customers( cust_id int NOT NULL AUTO_INCREMENT, cust_name ... 阅读全文
posted @ 2015-08-22 11:15 lasclocker 阅读(344) 评论(0) 推荐(0)
一条Top10热销品牌MySQL语句
摘要：表t_alibaba_data的数据结构如下：各列含义分别是：用户id(user_id)，品牌id(brand_id)，用户行为(type, 其中，点击为0，购买为1，加入收藏为2，加入购物车为3)，产生行为的时间(visit_datetime)。一、用一条sql语句，找出点击过热销品牌(Top10... 阅读全文
posted @ 2015-04-25 21:59 lasclocker 阅读(325) 评论(0) 推荐(0)