在 sql 中将一个表中的唯一数据插入到另一个表中
[英]inserting unique data from one table into another in sql
问题描述
我正在尝试将数据从一个表插入到 SQL 中的另一个表中。我的解决方案如下：
INSERT INTO CollegeStats (cName, appCount, minGPA, maxGPA)
SELECT cName, (SELECT COUNT(*) FROM apply WHERE cName = cName ), 1, 1
FROM College;
请忽略格式错误。 无论如何，我有 select count(*) 的这一部分正在检索每所大学的所有申请的完整列表。 当我在其他地方使用相同的 select 行时，但我做了类似的事情： SELECT COUNT(*) FROM apply WHERE cName = 'U of O它从该表中准确检索俄勒冈大学的申请数量。 我的问题是我如何使用相同的代码将select强制转换为 select 不同的值？
MRE：
CREATE TABLE IF NOT EXISTS College
(
State CHAR(2) NOT NULL,
cName VARCHAR(20) NOT NULL,
enrollment INT NOT NULL,
PRIMARY KEY (cName)
);
CREATE TABLE IF NOT EXISTS Major
(
major VARCHAR(30) NOT NULL,
PRIMARY KEY (major)
);
CREATE TABLE IF NOT EXISTS Student
(
sID INT NOT NULL,
sName VARCHAR(30) NOT NULL,
GPA FLOAT NOT NULL,
sizeHS INT NOT NULL,
PRIMARY KEY (sID)
);
CREATE TABLE IF NOT EXISTS MinimumGPA
(
minGPA FLOAT NOT NULL,
cName VARCHAR(20) NOT NULL,
major VARCHAR(30) NOT NULL,
PRIMARY KEY (cName, major),
FOREIGN KEY (cName) REFERENCES College(cName),
FOREIGN KEY (major) REFERENCES Major(major)
);
CREATE TABLE IF NOT EXISTS APPLY
(
decision SET('Y', 'N') NOT NULL,
sID INT NOT NULL,
cName VARCHAR(20) NOT NULL,
major VARCHAR(30) NOT NULL,
PRIMARY KEY (sID, cName, major),
FOREIGN KEY (sID) REFERENCES Student(sID),
FOREIGN KEY (cName, major) REFERENCES MinimumGPA(cName, major)
);
INSERT INTO Student (sId, sName, GPA, sizeHS) VALUES (123, 'Amy', 3.90, 1000);
INSERT INTO Student (sId, sName, GPA, sizeHS) VALUES (234, 'Bob', 3.60, 1500);
INSERT INTO Student (sId, sName, GPA, sizeHS) VALUES (345, 'Craig', 3.50, 500);
INSERT INTO Student (sId, sName, GPA, sizeHS) VALUES (456, 'Doris', 3.90, 1000);
INSERT INTO Student (sId, sName, GPA, sizeHS) VALUES (543, 'Craig', 3.40, 2000);
INSERT INTO Student (sId, sName, GPA, sizeHS) VALUES (567, 'Edward', 2.90, 2000);
INSERT INTO Student (sId, sName, GPA, sizeHS) VALUES (654, 'Amy', 3.90, 1000);
INSERT INTO Student (sId, sName, GPA, sizeHS) VALUES (678, 'Fay', 3.80, 200);
INSERT INTO Student (sId, sName, GPA, sizeHS) VALUES (765, 'Jay', 2.90, 1500);
INSERT INTO Student (sId, sName, GPA, sizeHS) VALUES (789, 'Gary', 3.40, 800);
INSERT INTO Student (sId, sName, GPA, sizeHS) VALUES (876, 'Irene', 3.90, 400);
INSERT INTO Student (sId, sName, GPA, sizeHS) VALUES (987, 'Helen', 4.00, 800);
INSERT INTO College (cName, State, enrollment) VALUES ('Cornell', 'NY', 21000);
INSERT INTO College (cName, State, enrollment) VALUES ('MIT', 'MA', 10000);
INSERT INTO College (cName, State, enrollment) VALUES ('WSU', 'WA', 28000);
INSERT INTO College (cName, State, enrollment) VALUES ('U of O', 'OR', 25000);
INSERT INTO Major (major) VALUES ('CS');
INSERT INTO Major (major) VALUES ('EE');
INSERT INTO Major (major) VALUES ('history');
INSERT INTO Major (major) VALUES ('biology');
INSERT INTO Major (major) VALUES ('bioengineering');
INSERT INTO Major (major) VALUES ('psychology');
INSERT INTO Major (major) VALUES ('marine biology');
INSERT INTO MinimumGPA (cName, major, minGPA) VALUES ('WSU', 'CS', 3.75);
INSERT INTO MinimumGPA (cName, major, minGPA) VALUES ('WSU', 'EE', 3.5);
INSERT INTO MinimumGPA (cName, major, minGPA) VALUES ('WSU', 'history', 2.8);
INSERT INTO MinimumGPA (cName, major, minGPA) VALUES ('U of O', 'CS', 3.6);
INSERT INTO MinimumGPA (cName, major, minGPA) VALUES ('U of O', 'biology', 3.75);
INSERT INTO MinimumGPA (cName, major, minGPA) VALUES ('Cornell','bioengineering', 3.8);
INSERT INTO MinimumGPA (cName, major, minGPA) VALUES ('Cornell','CS', 3.4);
INSERT INTO MinimumGPA (cName, major, minGPA) VALUES ('Cornell','EE', 3.6);
INSERT INTO MinimumGPA (cName, major, minGPA) VALUES ('Cornell','history', 3.6);
INSERT INTO MinimumGPA (cName, major, minGPA) VALUES ('Cornell','psychology', 2.8);
INSERT INTO MinimumGPA (cName, major, minGPA) VALUES ('MIT', 'biology', 3.5);
INSERT INTO MinimumGPA (cName, major, minGPA) VALUES ('MIT', 'bioengineering', 3.5);
INSERT INTO MinimumGPA (cName, major, minGPA) VALUES ('MIT', 'CS', 3.9);
INSERT INTO MinimumGPA (cName, major, minGPA) VALUES ('MIT', 'marine biology', 3.5);
INSERT INTO Apply (sID, cName, major, decision) VALUES (123, 'Cornell', 'EE', 'Y');
INSERT INTO Apply (sID, cName, major, decision) VALUES (123, 'WSU', 'CS', 'N');
INSERT INTO Apply (sID, cName, major, decision) VALUES (123, 'WSU', 'EE', 'N');
INSERT INTO Apply (sID, cName, major, decision) VALUES (123, 'U of O', 'CS', 'Y');
INSERT INTO Apply (sID, cName, major, decision) VALUES (123, 'MIT', 'CS', 'N');
INSERT INTO Apply (sID, cName, major, decision) VALUES (234, 'U of O', 'biology', 'N');
INSERT INTO Apply (sID, cName, major, decision) VALUES (345, 'Cornell', 'bioengineering', 'N');
INSERT INTO Apply (sID, cName, major, decision) VALUES (345, 'Cornell', 'CS', 'Y');
INSERT INTO Apply (sID, cName, major, decision) VALUES (345, 'Cornell', 'EE', 'N');
INSERT INTO Apply (sID, cName, major, decision) VALUES (345, 'MIT', 'bioengineering', 'Y');
INSERT INTO Apply (sID, cName, major, decision) VALUES (543, 'MIT', 'CS', 'N');
INSERT INTO Apply (sID, cName, major, decision) VALUES (678, 'Cornell', 'history', 'N');
INSERT INTO Apply (sID, cName, major, decision) VALUES (678, 'Cornell', 'psychology', 'Y');
INSERT INTO Apply (sID, cName, major, decision) VALUES (678, 'WSU', 'history', 'Y');
INSERT INTO Apply (sID, cName, major, decision) VALUES (765, 'WSU', 'history', 'Y');
INSERT INTO Apply (sID, cName, major, decision) VALUES (876, 'MIT', 'biology', 'Y');
INSERT INTO Apply (sID, cName, major, decision) VALUES (876, 'MIT', 'marine biology', 'N');
INSERT INTO Apply (sID, cName, major, decision) VALUES (876, 'WSU', 'CS', 'N');
INSERT INTO Apply (sID, cName, major, decision) VALUES (987, 'WSU', 'CS', 'Y');
INSERT INTO Apply (sID, cName, major, decision) VALUES (987, 'U of O', 'CS', 'Y');
CREATE TABLE IF NOT EXISTS CollegeStats
(
cName VARCHAR(20) NOT NULL,
appCount INT NOT NULL,
minGPA dec(3, 2) NOT NULL,
maxGPA dec(3, 2) NOT NULL,
PRIMARY KEY (cName)
);
INSERT INTO CollegeStats (cName, appCount, minGPA, maxGPA)
SELECT cName, (SELECT COUNT(*) FROM apply WHERE cName ), 1, 1
FROM College;
select * from collegestats;
我再次希望 output 是 CollegeStats 中的每一行在其相应行中正确应用 minGPA 和 maxGPA。 上面再次是我的尝试，但就像我说的那样，它显然不起作用，因为它为每一行生成“30”，这是应用程序的总数。 我需要 WSU 等的正确数量的应用程序 IE 6
我正在运行可从 mysql 网站获得的最新版本的 sql，所有这些我都试图在 mysql 工作台中完成
3 个解决方案
解决方案1
1 2022-02-23 08:21:19
您需要使用前缀指定拼贴画，以便 mysql 知道它应该使用哪个拼贴画名称
INSERT INTO CollegeStats (cName, appCount, minGPA, maxGPA)
SELECT c.cName, (SELECT COUNT(*) FROM apply WHERE cName = c.cName ), 1, 1
FROM College c;
解决方案2
1 已采纳 2022-02-23 08:24:40
您应该使用下面的查询。 我尝试了您的示例数据，它工作正常。
CREATE TABLE IF NOT EXISTS College
(
State CHAR(2) NOT NULL,
cName VARCHAR(20) NOT NULL,
enrollment INT NOT NULL,
PRIMARY KEY (cName)
);
CREATE TABLE IF NOT EXISTS Major
(
major VARCHAR(30) NOT NULL,
PRIMARY KEY (major)
);
CREATE TABLE IF NOT EXISTS Student
(
sID INT NOT NULL,
sName VARCHAR(30) NOT NULL,
GPA FLOAT NOT NULL,
sizeHS INT NOT NULL,
PRIMARY KEY (sID)
);
CREATE TABLE IF NOT EXISTS MinimumGPA
(
minGPA FLOAT NOT NULL,
cName VARCHAR(20) NOT NULL,
major VARCHAR(30) NOT NULL,
PRIMARY KEY (cName, major),
FOREIGN KEY (cName) REFERENCES College(cName),
FOREIGN KEY (major) REFERENCES Major(major)
);
CREATE TABLE IF NOT EXISTS APPLY
(
decision SET('Y', 'N') NOT NULL,
sID INT NOT NULL,
cName VARCHAR(20) NOT NULL,
major VARCHAR(30) NOT NULL,
PRIMARY KEY (sID, cName, major),
FOREIGN KEY (sID) REFERENCES Student(sID),
FOREIGN KEY (cName, major) REFERENCES MinimumGPA(cName, major)
);
INSERT INTO Student (sId, sName, GPA, sizeHS) VALUES (123, 'Amy', 3.90, 1000);
INSERT INTO Student (sId, sName, GPA, sizeHS) VALUES (234, 'Bob', 3.60, 1500);
INSERT INTO Student (sId, sName, GPA, sizeHS) VALUES (345, 'Craig', 3.50, 500);
INSERT INTO Student (sId, sName, GPA, sizeHS) VALUES (456, 'Doris', 3.90, 1000);
INSERT INTO Student (sId, sName, GPA, sizeHS) VALUES (543, 'Craig', 3.40, 2000);
INSERT INTO Student (sId, sName, GPA, sizeHS) VALUES (567, 'Edward', 2.90, 2000);
INSERT INTO Student (sId, sName, GPA, sizeHS) VALUES (654, 'Amy', 3.90, 1000);
INSERT INTO Student (sId, sName, GPA, sizeHS) VALUES (678, 'Fay', 3.80, 200);
INSERT INTO Student (sId, sName, GPA, sizeHS) VALUES (765, 'Jay', 2.90, 1500);
INSERT INTO Student (sId, sName, GPA, sizeHS) VALUES (789, 'Gary', 3.40, 800);
INSERT INTO Student (sId, sName, GPA, sizeHS) VALUES (876, 'Irene', 3.90, 400);
INSERT INTO Student (sId, sName, GPA, sizeHS) VALUES (987, 'Helen', 4.00, 800);
INSERT INTO College (cName, State, enrollment) VALUES ('Cornell', 'NY', 21000);
INSERT INTO College (cName, State, enrollment) VALUES ('MIT', 'MA', 10000);
INSERT INTO College (cName, State, enrollment) VALUES ('WSU', 'WA', 28000);
INSERT INTO College (cName, State, enrollment) VALUES ('U of O', 'OR', 25000);
INSERT INTO Major (major) VALUES ('CS');
INSERT INTO Major (major) VALUES ('EE');
INSERT INTO Major (major) VALUES ('history');
INSERT INTO Major (major) VALUES ('biology');
INSERT INTO Major (major) VALUES ('bioengineering');
INSERT INTO Major (major) VALUES ('psychology');
INSERT INTO Major (major) VALUES ('marine biology');
INSERT INTO MinimumGPA (cName, major, minGPA) VALUES ('WSU', 'CS', 3.75);
INSERT INTO MinimumGPA (cName, major, minGPA) VALUES ('WSU', 'EE', 3.5);
INSERT INTO MinimumGPA (cName, major, minGPA) VALUES ('WSU', 'history', 2.8);
INSERT INTO MinimumGPA (cName, major, minGPA) VALUES ('U of O', 'CS', 3.6);
INSERT INTO MinimumGPA (cName, major, minGPA) VALUES ('U of O', 'biology', 3.75);
INSERT INTO MinimumGPA (cName, major, minGPA) VALUES ('Cornell','bioengineering', 3.8);
INSERT INTO MinimumGPA (cName, major, minGPA) VALUES ('Cornell','CS', 3.4);
INSERT INTO MinimumGPA (cName, major, minGPA) VALUES ('Cornell','EE', 3.6);
INSERT INTO MinimumGPA (cName, major, minGPA) VALUES ('Cornell','history', 3.6);
INSERT INTO MinimumGPA (cName, major, minGPA) VALUES ('Cornell','psychology', 2.8);
INSERT INTO MinimumGPA (cName, major, minGPA) VALUES ('MIT', 'biology', 3.5);
INSERT INTO MinimumGPA (cName, major, minGPA) VALUES ('MIT', 'bioengineering', 3.5);
INSERT INTO MinimumGPA (cName, major, minGPA) VALUES ('MIT', 'CS', 3.9);
INSERT INTO MinimumGPA (cName, major, minGPA) VALUES ('MIT', 'marine biology', 3.5);
INSERT INTO Apply (sID, cName, major, decision) VALUES (123, 'Cornell', 'EE', 'Y');
INSERT INTO Apply (sID, cName, major, decision) VALUES (123, 'WSU', 'CS', 'N');
INSERT INTO Apply (sID, cName, major, decision) VALUES (123, 'WSU', 'EE', 'N');
INSERT INTO Apply (sID, cName, major, decision) VALUES (123, 'U of O', 'CS', 'Y');
INSERT INTO Apply (sID, cName, major, decision) VALUES (123, 'MIT', 'CS', 'N');
INSERT INTO Apply (sID, cName, major, decision) VALUES (234, 'U of O', 'biology', 'N');
INSERT INTO Apply (sID, cName, major, decision) VALUES (345, 'Cornell', 'bioengineering', 'N');
INSERT INTO Apply (sID, cName, major, decision) VALUES (345, 'Cornell', 'CS', 'Y');
INSERT INTO Apply (sID, cName, major, decision) VALUES (345, 'Cornell', 'EE', 'N');
INSERT INTO Apply (sID, cName, major, decision) VALUES (345, 'MIT', 'bioengineering', 'Y');
INSERT INTO Apply (sID, cName, major, decision) VALUES (543, 'MIT', 'CS', 'N');
INSERT INTO Apply (sID, cName, major, decision) VALUES (678, 'Cornell', 'history', 'N');
INSERT INTO Apply (sID, cName, major, decision) VALUES (678, 'Cornell', 'psychology', 'Y');
INSERT INTO Apply (sID, cName, major, decision) VALUES (678, 'WSU', 'history', 'Y');
INSERT INTO Apply (sID, cName, major, decision) VALUES (765, 'WSU', 'history', 'Y');
INSERT INTO Apply (sID, cName, major, decision) VALUES (876, 'MIT', 'biology', 'Y');
INSERT INTO Apply (sID, cName, major, decision) VALUES (876, 'MIT', 'marine biology', 'N');
INSERT INTO Apply (sID, cName, major, decision) VALUES (876, 'WSU', 'CS', 'N');
INSERT INTO Apply (sID, cName, major, decision) VALUES (987, 'WSU', 'CS', 'Y');
INSERT INTO Apply (sID, cName, major, decision) VALUES (987, 'U of O', 'CS', 'Y');
CREATE TABLE IF NOT EXISTS CollegeStats
(
cName VARCHAR(20) NOT NULL,
appCount INT NOT NULL,
minGPA dec(3, 2) NOT NULL,
maxGPA dec(3, 2) NOT NULL,
PRIMARY KEY (cName)
);
INSERT INTO CollegeStats (cName, appCount, minGPA, maxGPA)
SELECT cName as cNameX, (SELECT COUNT(*) FROM apply WHERE cName = cNameX ), 1, 1
FROM College;
select * from CollegeStats;
这是 output：
解决方案3
0 2022-02-23 09:49:15
找出整个解决方案：
INSERT INTO CollegeStats (cName, appCount, minGPA, maxGPA)
SELECT cName as cNameX,
(SELECT COUNT(*) FROM apply WHERE cName = cNameX),
(SELECT MIN(GPA) FROM Student LEFT JOIN Apply ON Student.sID = Apply.sID WHERE cName = cNameX),
(SELECT MAX(GPA) FROM Student LEFT JOIN Apply ON Student.sID = Apply.sID WHERE cName = cNameX)
FROM College;
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