数据库是postgresql。表table分别有A,B,C,D几个区间的条件数据，1、求A-B的交集？2、求A-C的交集，且不在B区间内的？3、求A-D交集，且不在B-C内的？

CREATE TABLE test (a int(10) NOT NULL,b int(11) NOT NULL,c int(11) NOT NULL,msg varchar(255) NOT NULL, PRIMARY KEY (a,b,c) ) ENGINE=InnoDB DEFAULT CHARSET=utf8

UPDATE test t1, (SELECT * FROM test WHERE C = 0) t2SET t1.D = t2.DWHERE t1.C = 1AND t1.A = t2.AAND t1.B = t2.B;

这里错误很多：Table 'startbbs.stb_users b' doesn't exist stb_users 我要用到两次，肯定得取别名，怎么办呢

CS 120 Module 3 Open-Ended Projects: MPLFor this project, you will design and implement one or two programs using multiple programminglanguages (including C++).Requirements• You have the option to work individually, with one partner, or in a team of three foreachproject.• All of your programming ...

Closures are self-contained blocks of functionality that can be passed around and used in your code.

controller： {代码...} html {代码...}

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1.数据库查询问题，数据量过大2.举个例子 {代码...} b表中数据量过亿，可能导致查询失败吗？有什么好的查询办法？

{代码...} 如果是上面的数据的话，这条sql应该满足了。。。在不满足，就不管了...... 这是我的查询结果

postgre, 一对多用数组 {代码...}

SELECT b.rank,c.score FROM (SELECT count(*)+1 as 'rank' FROM (SELECT id,u.score FROM 学生表 i LEFT JOIN (SELECT id,SUM(score)as score FROM 成绩表 GROUP BY id)u ON u.id=i.id ORDER BY u.score DESC) a WHERE a.score>(SELECT sum(score) FROM 成绩表 WHERE id=1)) bLEFT JOIN (SELECT sum(score)as score ...

select greatest(a,b,c) max from table_name

select * from xxx where FIND_IN_SET(a,'a,b,c')

{代码...} 报错:#1111 - Invalid use of group function sites是网站表comments表是评论一个网站对应多个评论现在想把评论的数量统计出来直接更新到sites 找到个方法了: {代码...}

SELECT A.VA_REGION_NAME AS AREA_NAME, A.VA_CIG_TRADEMARK AS CIG_NM, B.DE_BS_CXB AS CXB_REL, A.DE_BS_CXB_PRE AS CXB_PREFROM DCDW.FAC_SCC_ZY_REGION_CXB_PRE ALEFT JOIN DCDW.FAC_SCC_ZY_REGION_CXB B ON B.VA_CIG_TRADEMARK = A.VA_CIG_TRADEMARK AND A.VA_REGION_CODE = B.REGION_CODELEFT JOIN DIM_REGION C O...