序号 | 事件 | 说明 |
---|---|---|
01 | 整理昨日知识 | Vim,SQL语句 |
02 | 机器学习中的概念和研究的大致内容 | -- |
03 | SQL语句的学习 | 需求学习法:Django+mysql+web |
04 | 机器学习中的线性代数 | 线性代数 |
序号 | 概念 | 说明 |
---|---|---|
01 | SQL | structured query language:结构化查询语言 |
02 | SVD | -- |
03 | QR分解 | -- |
SELECT function(列) FROM 表
序号 | 函数 | 示例 |
---|---|---|
01 | AVG:平均数 | SELECT AVG(Realtime) FROM realtime_film; |
02 | COUNT:计数 | SELECT COUNT(Realtime) FROM realtime_film; |
03 | DISTINCT:唯一值 | SELECT DISTINCT Screen_time FROM realtime_film ; |
04 | MAX:最大值 | SELECT MAX(sum_movie)FROM realtime_film; |
05 | MIN:最小值 | SELECT MIN(sum_movie)FROM realtime_film; |
06 | SUM:全值相加 | SELECT MIN(sum_movie)FROM realtime_film; |
07 | GROUP BY:根据一个或多个列的结果排序 | SELECT Customer,OrderDate,SUM(OrderPrice) FROM Orders GROUP BY Customer,OrderDate |
08 | DELECT:删除语句 | DELETE FROM table_name [WHERE Clause] |
09 | LIKE | SELECT field1, field2,...fieldN table_name1, table_name2... WHERE field1 LIKE condition1 [AND [OR]] filed2 = 'somevalue' |
10 | ORDER BY:升序或降序排列 | SELECT field1, field2,...fieldN table_name1,table_name2...ORDER BY field1, [field2...] [ASC [DESC]] |