Merge pull request #6 from Servant-Software-LLC/5-unable-to-get-query…

…engine-results-with-select-column-aliases

The original column name in the queryOutput was provided in the …

src/Core/QueryProcessing/QueryEngine.cs

@@ -148,8 +148,11 @@ private IEnumerable<DataRow> ResolveSelectColumns(DataTable queryOutput, IEnumer
             var selectColumns = queryOutput.NewRow();
             foreach (DataColumn dataColumn in queryOutput.Columns)
             {
-                //Copy the column value from fromDataRows to the selectColumns
-                selectColumns[dataColumn.ColumnName] = dataRow[GetColumnName(dataColumn.ColumnName)];
+                //Items in the dataRow are using their original column names, so we need to get the original column name
+                var sqlColumn = dataColumn.ExProps().Column;
+
+                //Copy the column value from fromDataRows to the selectColumns. 
+                selectColumns[dataColumn.ColumnName] = dataRow[GetColumnName(sqlColumn.ColumnName)];
             }
 
             yield return selectColumns;

tests/Grammars/MySQL.Tests/QueryEngineTests.cs

@@ -0,0 +1,38 @@
+using Irony.Parsing;
+using SqlBuildingBlocks.Core.Tests.Utils;
+using SqlBuildingBlocks.Grammars.MySQL.Tests.Utils;
+using SqlBuildingBlocks.Interfaces;
+using SqlBuildingBlocks.LogicalEntities;
+using SqlBuildingBlocks.QueryProcessing;
+using SqlBuildingBlocks.Utils;
+using System.Linq;
+using Xunit;
+
+namespace SqlBuildingBlocks.Grammars.MySQL.Tests;
+
+public class QueryEngineTests
+{
+    [Fact]
+    public void Results_ColumnAlias()
+    {
+        SqlGrammarMySQL grammar = new();
+        var node = GrammarParser.Parse(grammar, @"SELECT VARIABLE_NAME Variable_name, VARIABLE_VALUE Value FROM performance_schema.session_variables WHERE VARIABLE_NAME LIKE 'sql_mode'");
+
+        FakeDatabaseConnectionProvider databaseConnectionProvider = new();
+        FakeTableDataProvider tableDataProvider = new();
+        SqlSelectDefinition selectDefinition = grammar.Create(node, databaseConnectionProvider, tableDataProvider, null);
+
+        Assert.False(selectDefinition.InvalidReferences);
+
+        AllTableDataProvider allTableDataProvider = new(new ITableDataProvider[] { tableDataProvider });
+        var queryEngine = new QueryEngine(allTableDataProvider, selectDefinition);
+
+        var queryResults = queryEngine.Query();
+
+        var results = queryResults.Results.ToList();
+
+        Assert.Equal(1, results.Count);
+        Assert.Equal("Variable_name", results[0].Table.Columns[0].ColumnName);
+        Assert.Equal("Value", results[0].Table.Columns[1].ColumnName);
+    }
+}

tests/Grammars/MySQL.Tests/Utils/FakeDatabaseConnectionProvider.cs

@@ -0,0 +1,10 @@
+using SqlBuildingBlocks.Interfaces;
+
+namespace SqlBuildingBlocks.Grammars.MySQL.Tests.Utils;
+
+internal class FakeDatabaseConnectionProvider : IDatabaseConnectionProvider
+{
+    public string DefaultDatabase { get; set; } = string.Empty;
+
+    public bool CaseInsensitive => true;
+}

tests/Grammars/MySQL.Tests/Utils/FakeTableDataProvider.cs

@@ -0,0 +1,39 @@
+using SqlBuildingBlocks.Interfaces;
+using SqlBuildingBlocks.LogicalEntities;
+using SqlBuildingBlocks.QueryProcessing;
+using System.Data;
+
+namespace SqlBuildingBlocks.Grammars.MySQL.Tests.Utils;
+
+public class FakeTableDataProvider : ITableDataProvider
+{
+    public IEnumerable<DataColumn> GetColumns(SqlTable table)
+    {
+        if (table.TableName == "session_variables")
+        {
+            yield return new DataColumn("VARIABLE_NAME", typeof(string));
+            yield return new DataColumn("VARIABLE_VALUE", typeof(string));
+            yield break;
+        }
+
+        throw new NotImplementedException();
+    }
+
+    public record variable(string VARIABLE_NAME, string VARIABLE_VALUE);
+
+    private IEnumerable<variable> GetEnumerable()
+    {
+        yield return new("activate_all_roles_on_login", "OFF");
+        yield return new("sql_mode", "STRICT_TRANS_TABLES,NO_ENGINE_SUBSTITUTION");
+    }
+    public IQueryable GetTableData(SqlTable table)
+    {
+        var result = GetEnumerable().AsQueryable();
+        return result;
+    }
+
+    public (bool DatabaseServiced, IEnumerable<SqlTableInfo> Tables) GetTables(string database)
+    {
+        throw new NotImplementedException();
+    }
+}

tests/Grammars/MySQL.Tests/Utils/SqlGrammarMySQL.cs

@@ -0,0 +1,25 @@
+using Irony.Parsing;
+using SqlBuildingBlocks.Interfaces;
+using SqlBuildingBlocks.LogicalEntities;
+
+namespace SqlBuildingBlocks.Grammars.MySQL.Tests.Utils;
+
+public class SqlGrammarMySQL : Grammar
+{
+    public SqlGrammarMySQL()
+    {
+        //MySQL has special naming rules for identifiers.  (Note: the backtick)
+        //REF: https://dev.mysql.com/doc/refman/8.0/en/identifiers.html
+        SqlBuildingBlocks.Grammars.MySQL.SimpleId simpleId = new(this);
+        Id id = new(this, simpleId);
+
+        SqlBuildingBlocks.Grammars.MySQL.SelectStmt selectStmt = new(this, id);
+
+        selectStmt.Expr.InitializeRule(selectStmt, selectStmt.FuncCall);
+        Root = selectStmt;
+    }
+
+    public virtual SqlSelectDefinition Create(ParseTreeNode selectStmt, IDatabaseConnectionProvider databaseConnectionProvider, ITableSchemaProvider tableSchemaProvider, IFunctionProvider functionProvider) =>
+        ((SelectStmt)Root).Create(selectStmt, databaseConnectionProvider, tableSchemaProvider, functionProvider);
+
+}