Zhongjie1986的博客

SQL Correlated SubqueryWHEN to use :1.when asking negative data questionshttps://learnsql.com/blog/correlated-sql-subquery-5-minutes/2.https://www.w3resource.com/sql-exercises/subqueries/sql-subqueries-inventory-exercise-11.php

SQL exists,not exists,INhttps://www.youtube.com/watch?v=zfgJ3ZmAgNw&t=20shttps://www.youtube.com/watch?v=GnYyX40Oclghttps://www.youtube.com/watch?v=EfkvHDsLwi0https://www.youtube.com/watch?v=EfkvHDsLwi0https://blog.youkuaiyun.com/xiangqian9/article/deta

SQL 合并两个表的数据1.通过共同的field valuedisplay all the customers with orders issued on date 17th August, 2012:SELECT c.customer_name, o.*FROM orders AS o,customer AS c # combine two tables togetherWHERE o.customer_id = c.customer_id

SQL Subquerycan be used inside of WHERE, SELECT,FROM1.when subquery is used inside WHERE, it returns a column2.when subquery is used inside FROM, it returns a table3.when subquery is used inside SELECT, it returns a single value

SQL Data CampSelf Jointable:populationscalculate the percentage increase in population from 2010 to 2015 for each country codeSELECT p1.country_code, p1.size AS size2010, p2.size AS size2015, -- 1. calculate growth_perc (

SQL Window Funcionshttps://www.youtube.com/watch?v=H6OTMoXjNiMhttps://www.youtube.com/watch?v=TzsrO4zTQj8分析函数的语法结构一般是：分析函数名(参数) OVER (PARTITION BY子句 ORDER BY子句 ROWS/RANGE子句)。即由以下三部分组成：分析函数名：如sum、max、min、count、avg等聚集函数以及lead、lag行比较函数等；over： 关键字，表示前面的

SQL 案例Self Join查找所有比Allen 工资高的员工table: employeeSELECT a.* ---select all columns in table a FROM employee AS a, employee AS b ----self join WHERE a.salary >b.salaryAND b.name ='ALLEN';

SQL Select Intohttps://www.youtube.com/watch?v=7od9V6EN6pkhttps://www.youtube.com/watch?v=s1Clw23uMrshttps://www.youtube.com/watch?v=YpLfUlihd5U

Self Joinhttps://www.youtube.com/watch?v=W0p8KP0o8g4https://www.youtube.com/watch?v=G4vO83UUzek

JOININNER JOIN and LEFT JOINhttps://www.youtube.com/watch?v=Q8yzRCz3Otw&list=PLFfxQqRQ0MuTLkcWBsLXVDXEyKSh7wnOJ&index=1https://www.youtube.com/watch?v=7yvB-tTHRfQ&list=PLFfxQqRQ0MuTLkcWBsLXVDXEyKSh7wnOJ&index=3&t=0shttps://www.

ON 子句与 WHERE 子句的不同