Add db.CreateParam() helper for creating detached Db params

Author: mythz

src/ServiceStack.OrmLite/Expressions/SqlExpression.cs

@@ -1705,5 +1705,41 @@ public class OrmLiteDataParameter : IDbDataParameter
         public byte Scale { get; set; }
         public int Size { get; set; }
     }
+
+    public static class DbDataParameterExtensions
+    {
+        public static IDbDataParameter CreateParam(this IDbConnection db,
+            string name,
+            object value=null,
+            DbType? dbType=null,
+            bool? isNullable=null,
+            byte? precision=null,
+            byte? scale=null,
+            int? size=null)
+        {
+            var dialectProvider = db.GetDialectProvider();
+
+            var to = new OrmLiteDataParameter
+            {
+                ParameterName = dialectProvider.GetParam(name),
+                Value = value,
+            };
+
+            var valueType = value != null ? value.GetType() : typeof(string);
+            if (dbType != null)
+                to.DbType = dbType.GetValueOrDefault(dialectProvider.GetColumnDbType(valueType));
+
+            to.IsNullable = isNullable.GetValueOrDefault(value == null || !valueType.IsNullableType());
+
+            if (precision != null)
+                to.Precision = precision.Value;
+            if (scale != null)
+                to.Scale = scale.Value;
+            if (size != null)
+                to.Size = size.Value;
+
+            return to;
+        }
+    }
 }
 

src/ServiceStack.OrmLite/OrmLiteReadApiAsync.cs

@@ -183,6 +183,14 @@ public static Task<T> SingleFmtAsync<T>(this IDbConnection dbConn, string sqlFor
             return dbConn.Exec(dbCmd => dbCmd.SingleWhereAsync<T>(name, value, token));
         }
 
+        public static T ScalarAsync<T>(this IDbCommand dbCmd, string sql, IEnumerable<IDbDataParameter> sqlParams)
+        {
+            if (sqlParams != null)
+                dbCmd.SetParameters(sqlParams);
+
+            return dbCmd.Scalar<T>(sql);
+        }
+
         /// <summary>
         /// Returns a single scalar value using an SqlExpression. E.g:
         /// <para>db.Column&lt;int&gt;(db.From&lt;Persion&gt;().Select(x => Sql.Count("*")).Where(q => q.Age > 40))</para>