创建数据库、创建数据表（包括主外键约束以及用户自定义约束）、创建视图、等对象的SQL代码语句

以下是一个简单的示例，包括创建数据库、创建数据表、创建主外键约束、用户自定义约束和创建视图的 SQL 代码语句：

1. 创建数据库

CREATE DATABASE mydatabase;

2. 创建数据表

CREATE TABLE Students (
    StudentID int PRIMARY KEY,
    FirstName varchar(255) NOT NULL,
    LastName varchar(255) NOT NULL,
    Gender varchar(10) NOT NULL,
    BirthDate date NOT NULL,
    Email varchar(255) NOT NULL UNIQUE
);

CREATE TABLE Courses (
    CourseID int PRIMARY KEY,
    CourseName varchar(255) NOT NULL,
    Credits int NOT NULL
);

3. 创建主外键约束

ALTER TABLE Enrollments
ADD CONSTRAINT PK_Enrollments PRIMARY KEY (StudentID, CourseID);

ALTER TABLE Enrollments
ADD CONSTRAINT FK_Enrollments_Students FOREIGN KEY (StudentID)
REFERENCES Students(StudentID);

ALTER TABLE Enrollments
ADD CONSTRAINT FK_Enrollments_Courses FOREIGN KEY (CourseID)
REFERENCES Courses(CourseID);

4. 创建用户自定义约束

ALTER TABLE Students
ADD CONSTRAINT CHK_Students_Gender CHECK (Gender IN ('M', 'F'));

ALTER TABLE Courses
ADD CONSTRAINT CHK_Courses_Credits CHECK (Credits >= 1 AND Credits <= 5);

5. 创建视图

CREATE VIEW StudentCourses AS
SELECT Students.FirstName, Students.LastName, Courses.CourseName, Courses.Credits
FROM Students
INNER JOIN Enrollments ON Students.StudentID = Enrollments.StudentID
INNER JOIN Courses ON Enrollments.CourseID = Courses.CourseID;

以上是一个简单的示例，根据具体情况，您需要根据具体需求进行适当的修改。