QueryPage

CHANGELOG.md

@@ -3,9 +3,11 @@
 - the DTO code-generator now has a parameter that allows generating C# records: ```--model-type ImmutableClass|Record``` or ```<SqModelGenType>ImmutableClass|Record</SqModelGenType>```;
 - "CheckExistenceBy" in the Insert data builder what adds WHERE EXISTS(...) to a Insert source to avoid duplicates inserting;
 - ExistsIn ...
+- QueryPage extension for OffsetFetch queries.
 ### Bugfix
 - When some column(s) in values constructor contains only nulls, sqexpress now adds an explicit type cast for the first cell e.g. ```CAST(NULL as int)```
 - **MergeDataInto** now allows only keys mapping unless **WhenMatchThenUpdate** is defined (without additional updates)
+- Derived tables now can have 0 declared columns
 
 # 0.3.0.0
 ### New Features

SqExpress/ExprExtension.cs

@@ -4,8 +4,10 @@
 using System.Xml;
 using SqExpress.DataAccess;
 using SqExpress.QueryBuilders;
+using SqExpress.QueryBuilders.Select;
 using SqExpress.QueryBuilders.Update;
 using SqExpress.Syntax;
+using SqExpress.Syntax.Select;
 using SqExpress.SyntaxTreeOperations;
 using SqExpress.SyntaxTreeOperations.ExportImport;
 using SqExpress.SyntaxTreeOperations.ExportImport.Internal;
@@ -67,6 +69,30 @@ public static Task<Dictionary<TKey, TValue>> QueryDictionary<TKey, TValue>(
         where TKey : notnull
             => database.QueryDictionary(query.Done(), keyFactory, valueFactory, keyDuplicationHandler, predicate);
 
+        public static Task<DataPage<T>> QueryPage<T>(this ISelectOffsetFetchBuilderFinal builder, ISqDatabase database, Func<ISqDataRecordReader, T> reader)
+            => builder.Done().QueryPage(database, reader);
+
+        public static async Task<DataPage<T>> QueryPage<T>(this ExprSelectOffsetFetch query, ISqDatabase database, Func<ISqDataRecordReader, T> reader)
+        {
+            var countColumn = CustomColumnFactory.Int32("$count$");
+
+            var selectQuery = (ExprQuerySpecification)query.SelectQuery;
+
+            query = query.WithSelectQuery(
+                selectQuery.WithSelectList(selectQuery.SelectList.Concat(SqQueryBuilder.CountOneOver().As(countColumn))));
+
+            var res = await query.Query(database,
+                new KeyValuePair<List<T>, int?>(new List<T>(), null),
+                (acc, r) =>
+                {
+                    acc.Key.Add(reader(r));
+                    var total = acc.Value ?? countColumn.Read(r);
+                    return new KeyValuePair<List<T>, int?>(acc.Key, total);
+                });
+
+            return new DataPage<T>(res.Key, query.OrderBy.OffsetFetch.Offset.Value ?? 0, res.Value ?? 0);
+        }
+
         public static Task<object> QueryScalar(this IExprQuery query, ISqDatabase database)
             => database.QueryScalar(query);
 

SqExpress/ModelRequestExtensions.cs

@@ -3,7 +3,6 @@
 using System.Threading.Tasks;
 using SqExpress.DataAccess;
 using SqExpress.ModelSelect;
-using SqExpress.Syntax.Select;
 
 namespace SqExpress
 {
@@ -20,27 +19,5 @@ public static Task<TAcc> Query<TRes,TAcc>(this ModelRequestData<TRes> modelReque
 
         public static Task<DataPage<TRes>> QueryPage<TRes>(this ModelRangeRequestData<TRes> modelRequestData, ISqDatabase database)
             => modelRequestData.Expr.QueryPage(database, modelRequestData.Mapper);
-
-        internal static async Task<DataPage<T>> QueryPage<T>(this ExprSelectOffsetFetch query, ISqDatabase database, Func<ISqDataRecordReader, T> reader)
-        {
-            var countColumn = CustomColumnFactory.Int32("$count");
-
-            var selectQuery = (ExprQuerySpecification)query.SelectQuery;
-
-            query = query.WithSelectQuery(
-                selectQuery.WithSelectList(selectQuery.SelectList.Concat(SqQueryBuilder.CountOneOver().As(countColumn))));
-
-
-            var res = await query.Query(database,
-                new KeyValuePair<List<T>, int?>(new List<T>(), null),
-                (acc, r) =>
-                {
-                    acc.Key.Add(reader(r));
-                    var total = acc.Value ?? countColumn.Read(r);
-                    return new KeyValuePair<List<T>, int?>(acc.Key, total);
-                });
-
-            return new DataPage<T>(res.Key, query.OrderBy.OffsetFetch.Offset.Value ?? 0, res.Value ?? 0);
-        }
     }
 }

SqExpress/SqExpress.csproj

@@ -7,7 +7,7 @@
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
     <Authors>Dmitry Tikhonov</Authors>
     <Company />
-    <Version>0.3.0.2</Version>
+    <Version>0.3.1.0</Version>
     <Summary>SqExpress is a sql query builder which allows creating SQL expression directly in C# code with strong typing and intellisense.</Summary>
     <PackageReleaseNotes>https://github.com/0x1000000/SqExpress/blob/main/CHANGELOG.md</PackageReleaseNotes>
     <Description>SqExpress is a sql query builder which allows creating SQL expression in C# code with strong typing and intellisense (without LINQ!).
@@ -29,8 +29,8 @@ This an article that explains the library principles: ["Syntax Tree and Alternat
     <Copyright>Dmitry Tikhonov</Copyright>
     <PackageProjectUrl>https://github.com/0x1000000/SqExpress</PackageProjectUrl>
     <PackageTags>query postgresql  tsql mysql builder mssql dataaccess</PackageTags>
-    <AssemblyVersion>0.3.0.2</AssemblyVersion>
-    <FileVersion>0.3.0.2</FileVersion>
+    <AssemblyVersion>0.3.1.0</AssemblyVersion>
+    <FileVersion>0.3.1.0</FileVersion>
     <AssemblyOriginatorKeyFile>..\SqExpress.snk</AssemblyOriginatorKeyFile>
     <SignAssembly>true</SignAssembly>
     <DelaySign>false</DelaySign>

SqExpress/SqQueryBuilder.cs

@@ -60,6 +60,12 @@ public static ExprCast Cast(ExprValue expression, ExprType asType)
         public static ExprCast Cast(IExprSelecting expression, ExprType asType) 
             => new ExprCast(expression, asType);
 
+        public static ExprColumn Column(string columnName) 
+            => new ExprColumn(null, columnName);
+
+        public static ExprColumn Column(IExprColumnSource source, string columnName) 
+            => new ExprColumn(source, columnName);
+
         public static ExprTableAlias TableAlias(Alias alias = default)
             => new ExprTableAlias(alias.BuildAliasExpression() ?? Alias.Auto.BuildAliasExpression()!);
 

SqExpress/SqlExport/Internal/SqlBuilderBase.cs

@@ -1129,9 +1129,8 @@ public bool VisitExprDerivedTableQuery(ExprDerivedTableQuery exprDerivedTableQue
         {
             this.AcceptPar('(', exprDerivedTableQuery.Query, ')', exprDerivedTableQuery);
             exprDerivedTableQuery.Alias.Accept(this, exprDerivedTableQuery);
-            if (exprDerivedTableQuery.Columns != null)
+            if (exprDerivedTableQuery.Columns != null && exprDerivedTableQuery.Columns.Count > 0)
             {
-                exprDerivedTableQuery.Columns.AssertNotEmpty("List of columns in a derived table with values literals cannot be empty");
                 var selectedColumns = exprDerivedTableQuery.Query.GetOutputColumnNames();
 
                 if (selectedColumns.Count != exprDerivedTableQuery.Columns.Count)