Add Documentation for Dapper.SqlBuilder (Issue #688, #480) (#1679)

Add Documentation for Dapper.SqlBuilder (Issue #688, #480)

Dapper.SqlBuilder/Readme.md

+Dapper.SqlBuilder - a simple sql formatter for .Net
+========================================
+[![Build status](https://ci.appveyor.com/api/projects/status/1w448i6nfxd14w75?svg=true)](https://ci.appveyor.com/project/StackExchange/dapper-SqlBuilder)
+
+Packages
+--------
+
+MyGet Pre-release feed: https://www.myget.org/gallery/dapper
+
+| Package                                                      | NuGet Stable                                                 | NuGet Pre-release                                            | Downloads                                                    | MyGet                                                        |
+| ------------------------------------------------------------ | ------------------------------------------------------------ | ------------------------------------------------------------ | ------------------------------------------------------------ | ------------------------------------------------------------ |
+| [Dapper.SqlBuilder](https://www.nuget.org/packages/Dapper.SqlBuilder/) | [![Dapper.SqlBuilder](https://img.shields.io/nuget/v/Dapper.SqlBuilder.svg)](https://www.nuget.org/packages/Dapper.SqlBuilder/) | [![Dapper.SqlBuilder](https://img.shields.io/nuget/vpre/Dapper.SqlBuilder.svg)](https://www.nuget.org/packages/Dapper.SqlBuilder/) | [![Dapper.SqlBuilder](https://img.shields.io/nuget/dt/Dapper.SqlBuilder.svg)](https://www.nuget.org/packages/Dapper.SqlBuilder/) | [![Dapper.SqlBuilder MyGet](https://img.shields.io/myget/dapper/vpre/Dapper.SqlBuilder.svg)](https://www.myget.org/feed/dapper/package/nuget/Dapper.SqlBuilder) |
+
+Features
+--------
+
+Dapper.SqlBuilder contains a number of helper methods for generating sql. 
+
+The list of extension methods in Dapper.SqlBuilder right now are:
+
+```csharp
+SqlBuilder AddParameters(dynamic parameters);
+SqlBuilder Select(string sql, dynamic parameters = null);
+SqlBuilder Where(string sql, dynamic parameters = null);
+SqlBuilder OrWhere(string sql, dynamic parameters = null);
+SqlBuilder OrderBy(string sql, dynamic parameters = null);
+SqlBuilder GroupBy(string sql, dynamic parameters = null);
+SqlBuilder Having(string sql, dynamic parameters = null);
+SqlBuilder Set(string sql, dynamic parameters = null);
+SqlBuilder Join(string sql, dynamic parameters = null);
+SqlBuilder InnerJoin(string sql, dynamic parameters = null);
+SqlBuilder LeftJoin(string sql, dynamic parameters = null);
+SqlBuilder RightJoin(string sql, dynamic parameters = null);
+SqlBuilder Intersect(string sql, dynamic parameters = null);
+```
+
+
+Template
+--------
+
+SqlBuilder allows you to generate N SQL templates from a composed query, it can easily format sql when you are attaching parameters and how, e.g:  
+```csharp
+var builder = new SqlBuilder()
+    .Where("a = @a", new { a = 1 })
+    .Where("b = @b", new { b = 2 })
+    .OrderBy("a")
+    .OrderBy("b");
+var counter = builder.AddTemplate("select count(*) from table /**where**/");
+var selector = builder.AddTemplate("select * from table /**where**/ /**orderby**/");
+var count = cnn.Query(counter.RawSql, counter.Parameters).Single();
+var rows = cnn.Query(selector.RawSql, selector.Parameters);
+```
+
+it's same as 
+```csharp
+var count = cnn.Query("select count(*) from table where a = @a and b = @b", new { a = 1, b = 1 });
+var rows = cnn.Query("select * from table where a = @a and b = @b order by a, b", new { a = 1, b = 1 });
+```
+
+Dynamic Filter Paging Example
+----------
+
+```csharp
+var builder = new SqlBuilder();
+var selectTemplate = builder.AddTemplate(@"select X.* from (
+        select us.*, ROW_NUMBER() OVER (/**orderby**/) AS RowNumber 
+        from Users us 
+        /**where**/
+    ) as X 
+    where RowNumber between @start and @finish", new { start, finish });
+var countTemplate = builder.AddTemplate(@"select count(*) from Users /**where**/");
+
+if (userId.HasValue())
+    builder.Where($"t.userId = @{nameof(userId)}", new { userId });
+if (isCancel)
+    builder.Where($"t.isCancel = @{nameof(isCancel)}", new { isCancel });
+
+builder.OrderBy(string.Format("t.id {0}", orderDesc ? "desc" : "asc"));
+
+var users = conn.Query<User>(selectTemplate.RawSql, selectTemplate.Parameters);
+var count = conn.ExecuteScalar<int>(countTemplate.RawSql, countTemplate.Parameters);
+//..etc..
+```
+
+Limitations and caveats
+--------
+
+OrWhere use `and` not `or` to concat sql problem
+
+[Issue 647](https://github.com/DapperLib/Dapper/issues/647) 
+
+```csharp
+sql.Where("a = @a1");
+sql.OrWhere("b = @b1");
+sql.Where("a = @a2");
+sql.OrWhere("b = @b2");
+```
+
+SqlBuilder will generate sql
+```sql=
+a = @a1 AND b = @b1 AND a = @a2 AND b = @b2
+```
+
+not
+```sql
+a = @a1 OR b = @b1 AND a = @a2 OR b = @b2
+```