代码演示

表结构

TBUser

TBInfo

DatabaseFirst

模型类

public class TBUser implements IModel {
    public int Guid;
    public String Name;
}

public class TBInfo implements IModel {
    public int Guid;
    public int Age;
    public int Score;
}

PS:在模型类中,默认主键为第一个元素

上下文类

public class MyContext extends DbContext {

    public MyContext() throws Exception {
        onCreate();
    }

    public DbSet<TBUser> TbUser = new DbSet<>(TBUser.class);
    public DbSet<TBInfo> TbInfo = new DbSet<>(TBInfo.class);


    @Override
    protected void onCreate() throws Exception {
        this.useSqlOperation(MySqlOperation.useDefault());
        this.run();
    }
}

所有上下文需要继承DbContext,然后把所有的表模型初始化到DbSet中,记得重写onCreate函数

实例化使用

先创建5条User数据

public class Main {
    public static void main(String[] args) throws Exception {

        MyContext context = new MyContext();

        context.TbUser.add(new TBUser(0, "Alice"));
        context.TbUser.add(new TBUser(1, "Bob"));
        context.TbUser.add(new TBUser(2, "Elima"));
        context.TbUser.add(new TBUser(3, "Win"));
        context.TbUser.add(new TBUser(4, "Gin"));

        context.saveChanges();

    }
}

查看这5条数据

public class Main {
    public static void main(String[] args) throws Exception {

        MyContext context = new MyContext();

        var result = context.TbUser
                .select(s->String.format("%s的编号为%d", s.Name, s.Guid));

        QueryLoader.StdOutput(result);

    }
}
>>>>>
Alice的编号为0
Bob的编号为1
Elima的编号为2
Win的编号为3
Gin的编号为4

进程已结束,退出代码0

我们生成一部分的TbInfo

public class Main {
    public static void main(String[] args) throws Exception {
        MyContext context = new MyContext();
        Random random = new Random();

        context.TbUser
                .where(s -> s.Name.length() <= 3 || s.Name.startsWith("A"))
                .select(s -> new TBInfo(s.Guid, random.nextInt(30), random.nextInt(100)))
                .toList()
                .forEach((Consumer<? super TBInfo>) s -> {
                    try {
                        context.TbInfo.add(s);
                    } catch (Exception e) {
                        throw new RuntimeException(e);
                    }
                });

        context.saveChanges();
    }
}

我们先查询到Elima的数据并删除它

public class Main {
    public static void main(String[] args) throws Exception {
        MyContext context = new MyContext();
        var elima = context.TbUser.where(s->s.Name.equals("Elima")).firstOrDefault();
        //var elima = context.TbUser.firstOrDefault(s->s.Name.equals("Elima")); 同样可以使用
        context.TbUser.remove(elima);
        context.saveChanges();
    }
}

然后我们联合查询一下两张表,使用join函数,并更新Score排序

public class Main {
    public static void main(String[] args) throws Exception {
        MyContext context = new MyContext();
        var result = context
                .TbUser
                .join(context.TbInfo,
                        s->s.Guid,
                        s->s.Guid,
                        s->s)
                .orderBy(s->s.B.Score)
                .reverse()
                .select(s->String.format("编号%d的名称为%s,年龄为%d,得分为%d",s.A.Guid,s.A.Name,s.B.Age,s.B.Score));
        QueryLoader.StdOutput(result);
    }
}
>>>>>
编号1的名称为Bob,年龄为3,得分为67
编号3的名称为Win,年龄为18,得分为56
编号0的名称为Alice,年龄为15,得分为36
编号4的名称为Gin,年龄为14,得分为25

进程已结束,退出代码0

CodeFirst

模型类

首先构建模型类

public class TBUser implements IModel {
    @MainKey
    @Type(type = DataType.integer)
    public int Guid;

    @Type(type = DataType.nchar, length = 10)
    @Nullable
    public String Name;
    public TBUser(){}
    public TBUser(int guid, String name){
        Guid = guid;
        Name = name;
    }
}

public class TBInfo implements IModel {
    @MainKey
    @Type(type = DataType.integer)
    public int Guid;
    @Type(type = DataType.integer)
    @Nullable
    public int Age;
    @Type(type = DataType.integer)
    @Nullable
    public int Score;
    public TBInfo(){}
    public TBInfo(int guid, int age, int score){
        Guid = guid;
        Age = age;
        Score = score;
    }
}

@MainKey唯一指定,主键
@Nullable可空类型
@Length字符类型的指定长度
@Type指定字段类型
目前支持的类型有

• nchar
• int
• datetime
• varchar

上下文类

与DatabaseFirst相比,有一点差距就是onLoad的重写,其他都是一样的

@Override
    protected void onCreate() throws Exception {
        this.useSqlOperation(MySqlOperation.useDefault());
        this.build();
        this.run();
    }

实例化使用

public class Main {
    public static void main(String[] args) throws Exception {
        MyContext context = new MyContext();
    }
}

创建成功后,请把onCreate中删除build语句,不然会重复创建报错
后续操作与DatabaseFirst相同

项目结构

具体下载链接见后续帖子,或者留言私信作者…

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