Table of Contents

ShadowSql.Expressions

  • .net拼接sql工具
  • 支持多种数据库,包括MsSql,MySql,Oracle,Sqlite,Postgres等,可扩展其他数据库方言的支持
  • 整个sql拼写只使用1个StringBuilder,减少字符串碎片生成
  • 在ShadowSql.Core项目基础上,增加表达式树的支持
  • 支持表达式树拼接sql
  • Nuget包名: ShadowSql.Expressions

1. 表达式查询

1.1 按常量查询

var query = new TableSqlQuery<User>("Users")
    .Where(u => u.Name == "张三");
// SELECT * FROM [Users] WHERE [Name]='张三'

1.2 按参数查询

var query = new TableSqlQuery<User>()
    .Where<UserParameter>((u, p) =>  u.Age > p.Age2);
// SELECT * FROM [User] WHERE [Age]>@Age2

2. 表达式排序

2.1 对单个字段排序

var cursor = new Table("Users")
    .Take<User>(10)
    .Asc(u => u.Id);
// SELECT TOP 10 * FROM [Users] ORDER BY [Id]

2.2 对多个字段排序

var cursor = new Table("Users")
    .Take<User>(10)
    .Desc(u => new { u.Age, u.Id });
// SELECT TOP 10 * FROM [Users] ORDER BY [Age] DESC,[Id] DESC

3. 联表查询

3.1 主外键联表

var query = new Table("Users")
    .SqlJoin<User, UserRole>(new Table("UserRoles"))
    .On(u => u.Id, r => r.UserId);
// SELECT * FROM [Users] AS t1 INNER JOIN [UserRoles] AS t2 ON t1.[Id]=t2.[UserId]

3.2 逻辑表达式联表

var query = new Table("Users")
    .SqlJoin<User, UserRole>(new Table("UserRoles"))
    .On((u, r) => u.Id == r.UserId);
// SELECT * FROM [Users] AS t1 INNER JOIN [UserRoles] AS t2 ON t1.[Id]=t2.[UserId]

4. 插入

4.1 插入常量值

var insert = EmptyTable.Use("Users")
    .ToInsert(() => new User { Name = "张三", Age = 18 });
// INSERT INTO [Users]([Name],[Age])VALUES('张三',18)

4.2 插入参数

var insert = EmptyTable.Use("Users")
    .ToInsert<UserParameter, User>(u => new User { Name = u.Name2, Age = u.Age2 });
// INSERT INTO [Users]([Name],[Age])VALUES(@Name2,@Age2)

5. 表达式删除

var delete = new TableSqlQuery<Student>("Students")
    .Where(s => s.Score < 60)
    .ToDelete();
// DELETE FROM [Students] WHERE [Score]<60

6. 表达式更新

6.1 常量更新

var update = EmptyTable.Use("Users")
    .ToUpdate<User>(u => u.Id == 1)
    .Set(u => new User { Age = 18 });
// UPDATE [Users] SET [Age]=18 WHERE [Id]=1

6.2 参数化更新

var user = new User { Id =1, Age = 18 };
var update = EmptyTable.Use("Users")
    .ToUpdate<User>(u => u.Id == user.Id)
    .Set(u => new User { Age = user.Age });
// UPDATE [Users] SET [Age]=@Age WHERE [Id]=@Id

6.3 原值叠加更新

var update = EmptyTable.Use("Students")
    .ToUpdate<Student>(u => u.Score < 60 && u.Score > 55)
    .Set(u => new Student { Score = u.Score + 5 });
// UPDATE [Students] SET [Score]=([Score]+5) WHERE [Score]<60 AND [Score]>55

7、表达式获取数据

7.1 直接获取全表

  • 调用ToSelect
var select = _db.From("Users")
    .ToSelect<User>()
    .Select(u => new { u.Id, u.Name });
// SELECT [Id],[Name] FROM [Users]

7.3 从表达式获取

  • 调用ToSelect
var select = _db.From("Users")
    .ToSelect<User>(u => u.Status)
    .Select(u => u.Id);
// SELECT [Id] FROM [Users] WHERE [Status]=1

7.3 从表查询获取

  • 调用路径:ToSqlQuery().ToSelect()
var select = _db.From("Users")
    .ToSqlQuery<User>()
    .Where(u => u.Status)
    .ToSelect()
    .Select(u => new { u.Id, u.Name });
// SELECT [Id],[Name] FROM [Users] WHERE [Status]=1

7.4 分页获取

  • 调用路径:ToSqlQuery().Take().ToSelect()
var select = _db.From("Users")
    .ToSqlQuery<User>()
    .Where(u => u.Status)
    .Take(10, 20)
    .Desc(u => u.Id)
    .ToSelect();
// SELECT * FROM [Users] WHERE [Status]=1 ORDER BY [Id] OFFSET 20 ROWS FETCH NEXT 10 ROWS ONLY
编辑本文