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28810 2a07c8bae6 mysql 表达式函数测试完成
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# FreeSql
打造 .NETCore 最方便的orm，dbfirst codefirst混合使用，codefirst模式下的开发阶段，建好实体不用执行任何，就能创建表和修改字段，dbfirst模式下提供api+模板，自定义生成代码，
https://github.com/2881099/FreeSql/blob/master/Docs/generator.md 默认提供了3种模板。
* [Insert 插入数据](Docs/insert.md)
* [Update 更新数据](Docs/update.md)
* [Delete 删除数据](Docs/delete.md)
* [Select 查询数据](Docs/select.md)
* [Expression 表达式函数](Docs/expression.md)
* [CodeFirst 快速开发](Docs/codefirst.md)
* [DbFirst 快速开发](Docs/dbfirst.md)
* [DbFirst 生成器](Docs/generator.md)
# 查询数据
```csharp
IFreeSql fsql = new FreeSql.FreeSqlBuilder()
.UseConnectionString(FreeSql.DataType.MySql, "Data Source=127.0.0.1;Port=3306;User ID=root;Password=root;Initial Catalog=cccddd;Charset=utf8;SslMode=none;Max pool size=10")
.Build();
ISelect<Topic> select => fsql.Select<Topic>();
[Table(Name = "tb_topic")]
class Topic {
[Column(IsIdentity = true, IsPrimary = true)]
public int Id { get; set; }
public int Clicks { get; set; }
public int TestTypeInfoGuid { get; set; }
public TestTypeInfo Type { get; set; }
public string Title { get; set; }
public DateTime CreateTime { get; set; }
}
class TestTypeInfo {
public int Guid { get; set; }
public int ParentId { get; set; }
public TestTypeParentInfo Parent { get; set; }
public string Name { get; set; }
}
class TestTypeParentInfo {
public int Id { get; set; }
public string Name { get; set; }
public List<TestTypeInfo> Types { get; set; }
}
```
### 返回 List
```csharp
List<Topic> t1 = select.Where(a => a.Id > 0).Skip(100).Limit(200).ToList();
```
### 返回 List + 导航属性的数据
```csharp
List<Topic> t2 = select.LeftJoin(a => a.Type.Guid == a.TestTypeInfoGuid).ToList();
//此时会返回普通字段 + 导航对象 Type 的数据
```
### 指定字段返回
```csharp
//返回一个字段
List<int> t3 = select.Where(a => a.Id > 0).Skip(100).Limit(200).ToList(a => a.Id);
//返回匿名类
List<匿名类> t4 = select.Where(a => a.Id > 0).Skip(100).Limit(200).ToList(a => new { a.Id, a.Title });
//返回元组
List<(int, string)> t5 = select.Where(a => a.Id > 0).Skip(100).Limit(200).ToList<(int, string)>("id, title");
```
### 执行SQL返回数据
```csharp
class xxx {
public int Id { get; set; }
public string Path { get; set; }
public string Title2 { get; set; }
}
List<xxx> t6 = fsql.Ado.Query<xxx>("select * from song");
List<(int, string ,string)> t7 = fsql.Ado.Query<(int, string, string)>("select * from song");
List<dynamic> t8 = fsql.Ado.Query<dynamic>("select * from song");
```
# 联表
### 使用导航属性联表
```csharp
sql = select.LeftJoin(a => a.Type.Guid == a.TestTypeInfoGuid).ToSql();
//SELECT a.`Id` as1, a.`Clicks` as2, a.`TestTypeInfoGuid` as3, a__Type.`Guid` as4, a__Type.`ParentId` as5, a__Type.`Name` as6, a.`Title` as7, a.`CreateTime` as8 FROM `tb_topic` a LEFT JOIN `TestTypeInfo` a__Type ON a__Type.`Guid` = a.`TestTypeInfoGuid`
sql = select
.LeftJoin(a => a.Type.Guid == a.TestTypeInfoGuid)
.LeftJoin(a => a.Type.Parent.Id == a.Type.ParentId).ToSql();
//SELECT a.`Id` as1, a.`Clicks` as2, a.`TestTypeInfoGuid` as3, a__Type.`Guid` as4, a__Type.`ParentId` as5, a__Type.`Name` as6, a.`Title` as7, a.`CreateTime` as8 FROM `tb_topic` a LEFT JOIN `TestTypeInfo` a__Type ON a__Type.`Guid` = a.`TestTypeInfoGuid` LEFT JOIN `TestTypeParentInfo` a__Type__Parent ON a__Type__Parent.`Id` = a__Type.`ParentId`
```
### 没有导航属性联表
```csharp
sql = select.LeftJoin<TestTypeInfo>((a, b) => b.Guid == a.TestTypeInfoGuid).ToSql();
//SELECT a.`Id` as1, a.`Clicks` as2, a.`TestTypeInfoGuid` as3, b.`Guid` as4, b.`ParentId` as5, b.`Name` as6, a.`Title` as7, a.`CreateTime` as8 FROM `tb_topic` a LEFT JOIN `TestTypeInfo` b ON b.`Guid` = a.`TestTypeInfoGuid`
sql = select
.LeftJoin<TestTypeInfo>((a, b) => b.Guid == a.TestTypeInfoGuid)
.LeftJoin<TestTypeParentInfo>((a, c) => c.Id == a.Type.ParentId).ToSql();
//SELECT a.`Id` as1, a.`Clicks` as2, a.`TestTypeInfoGuid` as3, b.`Guid` as4, b.`ParentId` as5, b.`Name` as6, a.`Title` as7, a.`CreateTime` as8 FROM `tb_topic` a LEFT JOIN `TestTypeInfo` b ON b.`Guid` = a.`TestTypeInfoGuid` LEFT JOIN `TestTypeParentInfo` c ON c.`Id` = b.`ParentId`
```
### 联表任意查
```csharp
sql = select.From<TestTypeInfo, TestTypeParentInfo>((s, b, c) => s
.LeftJoin(a => a.TestTypeInfoGuid == b.Guid)
.LeftJoin(a => b.ParentId == c.Id)).ToSql();
//SELECT a.`Id` as1, a.`Clicks` as2, a.`TestTypeInfoGuid` as3, b.`Guid` as4, b.`ParentId` as5, b.`Name` as6, a.`Title` as7, a.`CreateTime` as8 FROM `tb_topic` a LEFT JOIN `TestTypeInfo` b ON a.`TestTypeInfoGuid` = b.`Guid` LEFT JOIN `TestTypeParentInfo` c ON b.`ParentId` = c.`Id`
```
### 原生SQL联表
```csharp
sql = select.LeftJoin("TestTypeInfo b on b.Guid = a.TestTypeInfoGuid and b.Name = ?bname", new { bname = "xxx" }).ToSql();
//SELECT a.`Id` as1, a.`Clicks` as2, a.`TestTypeInfoGuid` as3, a.`Title` as4, a.`CreateTime` as5 FROM `tb_topic` a LEFT JOIN TestTypeInfo b on b.Guid = a.TestTypeInfoGuid and b.Name = ?bname
```
# 表达式函数
| 表达式 | MySql | SqlServer | PostgreSQL | 功能说明 |
| - | - | - | - | - |
| (a ?? b) | ifnull(a, b) | isnull(a, b) | coalesce(a, b) | 当a为null时，取b值 |
| 数字 + 数字 | a + b | a + b | a + b | 数字相加 |
| 数字 + 字符串 | concat(a, b) | cast(a as varchar) + cast(b as varchar) | case(a as varchar) \|\| b | 字符串相加，a或b任意一个为字符串时 |
| a - b | a - b | a - b | a - b | 减
| a * b | a * b | a * b | a * b | 乘
| a / b | a / b | a / b | a / b | 乘
| a % b | a mod b | a mod b | a mod b | 模
> 等等...
### 字符串对象
| 表达式 | MySql | SqlServer | PostgreSQL | 功能说明 |
| - | - | - | - | - |
| string.Empty | '' | '' | '' | 空字符串表示 |
| a.CompareTo(b) | a - b | - | - | 比较a和b大小 |
| a.Contains('b') | a like '%b%' | - | - | a是否包含b |
| a.EndsWith('b') | a like '%b' | - | - | a尾部是否包含b |
| a.IndexOf(b) | locate(a, b) - 1 | - | - | 查找a中出现b的位置 |
| a.Length | char_length(a) | - | - | 返回a的字符串长度 |
| a.PadLeft(b, c) | lpad(a, b, c) | - | - | 在a的左侧充字符c，直到字符串长度大于b |
| a.PadRight(b, c) | rpad(a, b, c) | - | - | 在a的右侧充字符c，直到字符串长度大于b |
| a.Replace(b, c) | replace(a, b, c) | - | - | 将a中字符串b，替换成c |
| a.StartsWith('b') | a like 'b%' | - | - | a头部是否包含b |
| a.Substring(b, c) | substr(a, b, c) | - | - | 截取a中位置b到c的内容 |
| a.ToLower | lower(a) | - | - | 转小写 |
| a.ToUpper | upper(a) | - | - | 转大写 |
| a.Trim | trim(a) | - | - | 移除两边字符 |
| a.TrimEnd | rtrim(a) | - | - | 移除左侧指定字符 |
| a.TrimStart | ltrim(a) | - | - | 移除右侧指定字符 |
### 日期对象
| 表达式 | MySql | SqlServer | PostgreSQL | 功能说明 |
| - | - | - | - | - |
| DateTime.Now | now() | - | - | 取本地时间 |
| DateTime.UtcNow | utc_timestamp() | - | - | 取UTC时间 |
| DateTime.Today | curdate | - | - | 取本地时间，日期部分 |
| DateTime.MaxValue | cast('9999/12/31 23:59:59' as datetime) | - | - | 最大时间 |
| DateTime.MinValue | cast('0001/1/1 0:00:00' as datetime) | - | - | 最小时间 |
| DateTime.Compare(a, b) | a - b | - | - | 比较a和b的大小 |
| DateTime.DaysInMonth(a, b) | dayofmonth(last_day(concat(a, '-', b, '-1'))) | - | - | 取指定年月份的总天数 |
| DateTime.Equals(a, b) | a = b | - | - | 比较a和b相等 |
| DateTime.IsLeapYear(a) | a%4=0 and a%100<>0 or a%400=0 | - | - | 判断闰年 |
| DateTime.Parse(a) | cast(a as datetime) | - | - | 转换日期类型 |
| a.Add(b) | date_add(a, interval b microsecond) | - | - | 增加TimeSpan值 |
| a.AddDays(b) | date_add(a, interval b day) | - | - | 增加天数 |
| a.AddHours(b) | date_add(a, interval b hour) | - | - | 增加小时 |
| a.AddMilliseconds(b) | date_add(a, interval b*1000 microsecond) | - | - | 增加毫秒 |
| a.AddMinutes(b) | date_add(a, interval b minute) | - | - | 增加分钟 |
| a.AddMonths(b) | date_add(a, interval b month) | - | - | 增加月 |
| a.AddSeconds(b) | date_add(a, interval b second) | - | - | 增加秒 |
| a.AddTicks(b) | date_add(a, interval b/10 microsecond) | - | - | 增加刻度，微秒的1/10 |
| a.AddYears(b) | date_add(a, interval b year) | - | - | 增加年 |
| a.Date | cast(date_format(a, '%Y-%m-%d') as datetime) | - | - | 获取a的日期部分 |
| a.Day | dayofmonth(a) | - | - | 获取a在月的第几天 |
| a.DayOfWeek | dayofweek(a) | - | - | 获取a在周的第几天 |
| a.DayOfYear | dayofyear(a) | - | - | 获取a在年的第几天 |
| a.Hour | hour(a) | - | - | 小时 |
| a.Millisecond | floor(microsecond(a) / 1000) | - | - | 毫秒 |
| a.Minute | minute(a) | - | - | 分钟 |
| a.Month | month(a) | - | - | 月 |
| a.Second | second(a) | - | - | 秒 |
| a.Subtract(b) | (time_to_sec(a) - time_to_sec(b)) * 1000000 + microsecond(a) - microsecond(b) | - | - | 将a的值和b相减 |
| a.Ticks | time_to_sec(a) * 10000000 + microsecond(a) * 10 + 62135596800000000 | - | - | 刻度总数 |
| a.TimeOfDay | time_to_sec(date_format(a, '1970-1-1 %H:%i:%s.%f')) * 1000000 + microsecond(a) + 6213559680000000 | - | - | 获取a的时间部分 |
| a.Year | year(a) | - | - | 年 |
| a.Equals(b) | a = b | - | - | 比较a和b相等 |
| a.CompareTo(b) | a - b | - | - | 比较a和b大小 |
| a.ToString() | date_format(a, '%Y-%m-%d %H:%i:%s.%f') | - | - | 转换字符串 |
### 时间对象
| 表达式 | MySql | SqlServer | PostgreSQL | 功能说明 |
| - | - | - | - | - |
| TimeSpan.Zero | 0 | - | - | 0微秒 |
| TimeSpan.MaxValue | 922337203685477580 | - | - | 最大微秒时间 |
| TimeSpan.MinValue | -922337203685477580 | - | - | 最小微秒时间 |
| TimeSpan.Compare(a, b) | a - b | - | - | 比较a和b的大小 |
| TimeSpan.Equals(a, b) | a = b | - | - | 比较a和b相等 |
| TimeSpan.FromDays(a) | a * 1000000 * 60 * 60 * 24 | - | - | a天的微秒值 |
| TimeSpan.FromHours(a) | a * 1000000 * 60 * 60 | - | - | a小时的微秒值 |
| TimeSpan.FromMilliseconds(a) | a * 1000 | - | - | a毫秒的微秒值 |
| TimeSpan.FromMinutes(a) | a * 1000000 * 60 | - | - | a分钟的微秒值 |
| TimeSpan.FromSeconds(a) | a * 1000000 | - | - | a秒钟的微秒值 |
| TimeSpan.FromTicks(a) | a / 10 | - | - | a刻度的毫秒值 |
| a.Add(b) | a + b | - | - | 增加值 |
| a.Subtract(b) | a - b | - | - | 将a的值和b相减 |
| a.CompareTo(b) | a - b | - | - | 比较a和b大小 |
| a.Days | a div (1000000 * 60 * 60 * 24) | - | - | 天数部分 |
| a.Hours | a div (1000000 * 60 * 60) mod 24 | - | - | 小时部分 |
| a.Milliseconds | a div 1000 mod 1000 | - | - | 毫秒部分 |
| a.Seconds | a div 1000000 mod 60 | - | - | 秒数部分 |
| a.Ticks | a * 10 | - | - | 刻度总数 |
| a.TotalDays | a / (1000000 * 60 * 60 * 24) | - | - | 总天数(含小数) |
| a.TotalHours | a / (1000000 * 60 * 60) | - | - | 总小时(含小数) |
| a.TotalMilliseconds | a / 1000 | - | - | 总毫秒(含小数) |
| a.TotalMinutes | a / (1000000 * 60) | - | - | 总分钟(含小数) |
| a.TotalSeconds | a / 1000000 | - | - | 总秒数(含小数) |
| a.Equals(b) | a = b | - | - | 比较a和b相等 |
| a.ToString() | | - | - | 转换字符串 |
### 数学函数
| 表达式 | MySql | SqlServer | PostgreSQL | 功能说明 |
| - | - | - | - | - |
| Math.Abs(a) | abs(a) | - | - | - |
| Math.Acos(a) | acos(a) | - | - | - |
| Math.Asin(a) | asin(a) | - | - | - |
| Math.Atan(a) | atan(a) | - | - | - |
| Math.Atan2(a, b) | atan2(a, b) | - | - | - |
| Math.Ceiling(a) | ceiling(a) | - | - | - |
| Math.Cos(a) | cos(a) | - | - | - |
| Math.Exp(a) | exp(a) | - | - | - |
| Math.Floor(a) | floor(a) | - | - | - |
| Math.Log(a) | log(a) | - | - | - |
| Math.Log10(a) | log10(a) | - | - | - |
| Math.PI(a) | 3.1415926535897931 | - | - | - |
| Math.Pow(a, b) | pow(a, b) | - | - | - |
| Math.Round(a, b) | round(a, b) | - | - | - |
| Math.Sign(a) | sign(a) | - | - | - |
| Math.Sin(a) | sin(a) | - | - | - |
| Math.Sqrt(a) | sqrt(a) | - | - | - |
| Math.Tan(a) | tan(a) | - | - | - |
| Math.Truncate(a) | truncate(a, 0) | - | - | - |
# 更多文档整理中。。。
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