TypesafeSQL

Linq-like SQL query builder for use with micro ORMs.

The purpose of TypesafeSQL is to allow for generate SQL queries in typesafe way, thus it's not a real Linq provider to relational database. It provides familiar linq syntax to express queries, but doesn't implement IQueryable.

Features

• select, where, order by
• inner joins,
• outer joins (not available with SQL-like syntax)
• group by
• count, sum, avg (only available in queries with group by)
• union, intersect, except
• almost all MS SQL functions
• subqueries (when defined outside a main query)
• easy integration with Dapper.NET
• mapping class names to table names and property names to column names with name resolvers

Supported databases

For now, only MS SQL 2012 is supported. Future releases will support MySQL, PostgreSQL and SQLite.

Examples

Simple SQL command generation:

var builder = new QueryBuilder();
var query = from u in builder.Table<User>() where u.LoginAttempts >= 3 select u;
var sql = query.ToSql();

Retrieving data with Dapper:

var connection = new SqlConnection(<Connection String>);
var builder = new QueryBuilder();
var users = connection.Query(from u in builder.Table<User>() where u.LoginAttempts >= 3 select u);

Inner joins:

var builder = new QueryBuilder();
var roles = from user in builder.Table<User>()
            join link in builder.Table<UserRoleLink>() on user.Id equals link.UserId
            join role in builder.Table<Role>() on link.RoleId equals role.Id
            select new { user.Login, Role = role.Name };

Outer joins:

var builder = new QueryBuilder();
var roles = builder.Table<User>()
    .LeftJoin(builder.Table<UserRoleLink>(), user => user.Id, link => link.UserId, (user, link) => new { user, link })
    .LeftJoin(builder.Table<Role>(), ul => ul.link.RoleId, role => role.Id, (ul, role) => new { ul, role })
    .Select(ulr => new { ulr.ul.user.Login, ulr.role.Name });

Group by:

var builder = new QueryBuilder();
var roleCounts = from l in builder.Table<UserRoleLink>()
                 group l by l.UserId into lg
                 select new { UserId = lg.Key, NumOfRoles = lg.Count(x => x.RoleId) };

Using name resolvers:

    public class PrefixBasedNameResolver : DefaultNameResolver
    {
        public override string ResolveTableName(Type modelClass)
        {
            return "tbl_" + base.ResolveTableName(modelClass);
        }
        
        public override string ResolveColumnName(System.Reflection.MemberInfo property)
        {
            return "col_" + base.ResolveColumnName(property);
        }
    }
    ...
    var builder = new QueryBuilder(new PrefixBasedNameResolver());
    ...