Address small review comments

Author: Jelte Fennema

DataGateway.Service/Resolvers/MsSqlQueryBuilder.cs

@@ -31,7 +31,7 @@ public string WrapSubqueryColumn(string column, SqlQueryStructure subquery)
 
         public string Build(SqlQueryStructure structure)
         {
-            string selectedColumns = String.Join(", ", structure.Columns.Select(x => $"{x.Value} AS {QuoteIdentifier(x.Key)}"));
+            string selectedColumns = string.Join(", ", structure.Columns.Select(x => $"{x.Value} AS {QuoteIdentifier(x.Key)}"));
             string fromPart = structure.Table(structure.TableName, structure.TableAlias);
             fromPart += String.Join(
                     "",

DataGateway.Service/Resolvers/PostgresQueryBuilder.cs

@@ -23,7 +23,7 @@ public string WrapSubqueryColumn(string column, SqlQueryStructure subquery)
 
         public string Build(SqlQueryStructure structure)
         {
-            string selectedColumns = String.Join(", ", structure.Columns.Select(x => $"{x.Value} AS {QuoteIdentifier(x.Key)}"));
+            string selectedColumns = string.Join(", ", structure.Columns.Select(x => $"{x.Value} AS {QuoteIdentifier(x.Key)}"));
             string fromPart = structure.Table(structure.TableName, structure.TableAlias);
             fromPart += String.Join("", structure.JoinQueries.Select(x => $" LEFT OUTER JOIN LATERAL ({Build(x.Value)}) AS {QuoteIdentifier(x.Key)} ON TRUE"));
             string query = $"SELECT {selectedColumns} FROM {fromPart}";

DataGateway.Service/Resolvers/SqlQueryEngine.cs

@@ -48,7 +48,7 @@ private static async Task<string> GetJsonStringFromDbReader(DbDataReader dbDataR
             // 1. https://docs.microsoft.com/en-us/sql/relational-databases/json/format-query-results-as-json-with-for-json-sql-server?view=sql-server-2017#output-of-the-for-json-clause
             // 2. https://stackoverflow.com/questions/54973536/for-json-path-results-in-ssms-truncated-to-2033-characters/54973676
             // 3. https://docs.microsoft.com/en-us/sql/relational-databases/json/use-for-json-output-in-sql-server-and-in-client-apps-sql-server?view=sql-server-2017#use-for-json-output-in-a-c-client-app
-            if (await dbDataReader.ReadAsync())
+            while (await dbDataReader.ReadAsync())
             {
                 jsonString.Append(dbDataReader.GetString(0));
             }