Question

我有sqlite3数据库，其中包含示例结构和数据：

CREATE TABLE person(id INTEGER PRIMARY KEY NOT NULL, name STRING NOT NULL);
INSERT INTO "person" VALUES(1,'Jack');
INSERT INTO "person" VALUES(2,'Daniel');
INSERT INTO "person" VALUES(3,'Sam');
INSERT INTO "person" VALUES(4,'T`lc');
CREATE TABLE vote(person_id INTEGER NOT NULL, article_id NUMBER NOT NULL, FOREIGN KEY(person_id) REFERENCES person(id));
INSERT INTO "vote" VALUES(1,43256);
INSERT INTO "vote" VALUES(1,43436);
INSERT INTO "vote" VALUES(1,67388);
INSERT INTO "vote" VALUES(1,43678);
INSERT INTO "vote" VALUES(2,678);
INSERT INTO "vote" VALUES(2,6788);
INSERT INTO "vote" VALUES(2,67388);
INSERT INTO "vote" VALUES(4,67388);
INSERT INTO "vote" VALUES(4,67658);

现在我想（在一个选择查询中）找到所有人的女巫：

根本不投票
不投票给第67388条

我不知道如何做到这一点：/

帮助：'（

Answer 1

使用OR：

SELECT p.*
   FROM PERSON p
 WHERE NOT EXISTS(SELECT NULL
                                FROM VOTE v
                               WHERE v.person_id = p.id) -- no votes at all
       OR NOT EXISTS(SELECT NULL
                                 FROM VOTE v
                                WHERE v.person_id = p.id
                                     AND v.article_id = 67388)

使用UNION

SELECT p.*
  FROM PERSON p
 WHERE NOT EXISTS(SELECT NULL
                                FROM VOTE v
                               WHERE v.person_id = p.id)
UNION
SELECT p.*
  FROM PERSON p
 WHERE NOT EXISTS(SELECT NULL
                                FROM VOTE v
                               WHERE v.person_id = p.id
                                    AND v.article_id = 67388)

UNION比UNION ALL慢，因为它会删除重复项。如果你想要重复，只需在“UNION”之后添加“ALL”关键字。

Answer 2

第1项：select id,name from person where id not in (select person_id from vote)

第2项：select id,name from person where id not in (select person_id from vote where article_id = 67388)

如何在sqlite中构建此查询？

2 个答案: