SQLSugar ORM框架：SqlQueryable使用教程

SQLSugar是一个ORM框架，可以通过SqlQueryable实现对数据库的查询操作。

使用步骤如下：

1. 引入命名空间

using SqlSugar;

2. 创建SqlSugarClient对象

var db = new SqlSugarClient(new ConnectionConfig
{
    ConnectionString = 'YourConnectionString',
    DbType = DbType.SqlServer,
    IsAutoCloseConnection = true,
    InitKeyType = InitKeyType.Attribute
});

3. 创建SqlQueryable对象

var queryable = db.Queryable<Entity>();

4. 添加查询条件

queryable = queryable.Where(it => it.Name.Contains('test'));

5. 添加排序规则

queryable = queryable.OrderBy(it => it.Id, OrderByType.Desc);

6. 执行查询操作

var list = queryable.ToList();

完整示例代码：

using SqlSugar;

class Program
{
    static void Main(string[] args)
    {
        var db = new SqlSugarClient(new ConnectionConfig
        {
            ConnectionString = 'YourConnectionString',
            DbType = DbType.SqlServer,
            IsAutoCloseConnection = true,
            InitKeyType = InitKeyType.Attribute
        });

        var queryable = db.Queryable<Entity>();
        queryable = queryable.Where(it => it.Name.Contains('test'));
        queryable = queryable.OrderBy(it => it.Id, OrderByType.Desc);
        var list = queryable.ToList();
    }
}

[SugarTable('Entity')]
public class Entity
{
    [SugarColumn(IsPrimaryKey = true, IsIdentity = true)]
    public int Id { get; set; }

    [SugarColumn(Length = 50, IsNullable = false)]
    public string Name { get; set; }

    [SugarColumn(IsNullable = true)]
    public int? Age { get; set; }
}