Wip/adr/add sqlserver offset

distribution/lib/Standard/Database/0.0.0-dev/src/DB_Table.enso

@@ -56,6 +56,7 @@ import project.Internal.Aggregate_Helper
 import project.Internal.Base_Generator
 import project.Internal.Common.Database_Join_Helper
 import project.Internal.Common.Lookup_Query_Helper
+import project.Internal.Common.Offset_Helpers
 import project.Internal.Common.Row_Number_Helpers
 import project.Internal.DB_Data_Link_Helpers
 import project.Internal.Helpers
@@ -3180,9 +3181,38 @@ type DB_Table
     @default (self-> Widget_Helpers.make_fill_default_value_selector2)
     @group_by Widget_Helpers.make_column_name_multi_selector
     @order_by Widget_Helpers.make_order_by_selector
-    offset self columns:(Vector (Integer | Text | Regex | By_Type))=(Missing_Argument.throw "columns") n:Integer=-1 fill_with:Fill_With=..Nothing (group_by:(Vector | Text | Integer | Regex)=[]) (order_by:(Vector | Text)=[]) (set_mode:Set_Mode=..Add) (on_problems:Problem_Behavior=..Report_Warning) -> Table =
-        _ = [columns, n, fill_with, group_by, order_by, set_mode, on_problems]
-        Error.throw (Unsupported_Database_Operation.Error "offset")
+    offset self columns:(Vector (Integer | Text | Regex | By_Type))=(Missing_Argument.throw "columns") n:Integer=-1 fill_with:Fill_With=..Nothing (group_by:(Vector | Text | Integer | Regex)=[]) (order_by:(Vector | Text)=[]) (set_mode:Set_Mode=..Add) (on_problems:Problem_Behavior=..Report_Warning) -> DB_Table =
+        Feature.Offset.if_supported_else_throw self.connection.dialect "offset" <|
+            problem_builder = Problem_Builder.new error_on_missing_columns=True
+            grouping_columns = self.columns_helper.select_columns_helper group_by Case_Sensitivity.Default True problem_builder
+            grouping_columns.each column->
+                if column.value_type.is_floating_point then
+                    problem_builder.report_other_warning (Floating_Point_Equality.Error column.name)
+            ordering = Table_Helpers.resolve_order_by self.columns order_by problem_builder
+            resolved_columns = self.columns_helper.select_columns_helper columns Case_Sensitivity.Default True problem_builder
+            problem_builder.attach_problems_before on_problems <| if columns.is_empty then self else
+                order_descriptors = case ordering.is_empty of
+                    False -> ordering.map element->
+                        column = element.column
+                        associated_selector = element.associated_selector
+                        self.connection.dialect.prepare_order_descriptor column associated_selector.direction text_ordering=Nothing
+                    True -> case self.default_ordering of
+                        Nothing -> Error.throw (Illegal_Argument.Error "The table has no existing ordering (e.g. from a `sort` operation or primary key). `offset` requires an ordering in database.")
+                        descriptors -> descriptors
+                grouping_expressions = (grouping_columns.map _.as_internal).map .expression
+                new_exprs = resolved_columns.map c->(Offset_Helpers.make_offset n (c.as_internal) order_descriptors grouping_expressions)
+
+                type_mapping = self.connection.dialect.get_type_mapping
+                infer_from_database_callback expression =
+                    SQL_Type_Reference.new self.connection self.context expression
+                new_type_refs = new_exprs.map expr->(type_mapping.infer_return_type infer_from_database_callback "OFFSET" [] expr)
+
+                new_names = resolved_columns.map c->(if set_mode==Set_Mode.Add then self.column_naming_helper.function_name "offset" [c, n, fill_with] else c.name)
+                new_columns = (new_names.zip new_type_refs).zip new_exprs a->b->(Internal_Column.Value a.first a.second b)
+
+                updated_table = new_columns.fold self t-> col->
+                    t.set (self.make_column col)
+                updated_table.as_subquery
 
 ## PRIVATE
 

distribution/lib/Standard/Database/0.0.0-dev/src/Internal/Base_Generator.enso

@@ -195,7 +195,7 @@ type SQL_Generator
         order_part = (SQL_Builder.join ", " orders) . prefix_if_present " ORDER BY "
 
         limit_part = case ctx.limit of
-                Nothing -> ""
+                Nothing -> "TOP 100 PERCENT "
                 _ : Integer -> dialect.get_limit_sql_modifier ctx.limit
 
         extensions = ctx.extensions.map extension->
@@ -467,7 +467,7 @@ base_dialect_operations =
     nulls = [["IS_NULL", make_right_unary_op "IS NULL"], ["FILL_NULL", make_function "COALESCE"]]
     contains = [["IS_IN", make_is_in], ["IS_IN_COLUMN", make_is_in_column]]
     types = [simple_cast]
-    windows = [["ROW_NUMBER", make_row_number], ["ROW_NUMBER_IN_GROUP", make_row_number_in_group]]
+    windows = [["ROW_NUMBER", make_row_number], ["ROW_NUMBER_IN_GROUP", make_row_number_in_group], ["LEAD", make_lead_lag "LEAD"], ["LAG", make_lead_lag "LAG"]]
     base_dict = Dictionary.from_vector (arith + logic + compare + functions + agg + counts + text + nulls + contains + types + windows)
     Dialect_Operations.Value base_dict
 
@@ -554,6 +554,20 @@ make_row_number (arguments : Vector) (metadata : Row_Number_Metadata) = if argum
         SQL_Builder.code "PARTITION BY " ++ SQL_Builder.join ", " grouping
     SQL_Builder.code "(row_number() OVER (" ++ group_part ++ " ORDER BY " ++ SQL_Builder.join ", " ordering ++ ") * " ++ step.paren ++ " + " ++ offset.paren ++ ")"
 
+## PRIVATE
+make_lead_lag lead_lag:Text arguments:Vector metadata:Row_Number_Metadata -> SQL_Builder = if arguments.length < 3 then Error.throw (Illegal_State.Error "Wrong amount of parameters in LEAD/LAG IR. This is a bug in the Database library.") else
+    n = arguments.at 0
+    colName = arguments.at 1
+
+    ordering_and_grouping = arguments.drop 2
+    ordering = ordering_and_grouping.drop (..Last metadata.groupings_count)
+    grouping = ordering_and_grouping.take (..Last metadata.groupings_count)
+
+    group_part = if grouping.length == 0 then "" else
+        SQL_Builder.code "PARTITION BY " ++ SQL_Builder.join ", " grouping
+
+    SQL_Builder.code "(" ++ lead_lag ++ "(" ++ colName ++ ", " ++ n ++ ", NULL) OVER (" ++ group_part ++ " ORDER BY " ++ SQL_Builder.join ", " ordering ++ "))"
+
 ## PRIVATE
    A helper for `lookup_and_replace`, and perhaps other operation.
    It creates an expression that returns a row number within a group.

distribution/lib/Standard/Database/0.0.0-dev/src/Internal/Common/Offset_Helpers.enso

@@ -0,0 +1,13 @@
+from Standard.Base import all
+
+import project.Internal.IR.Operation_Metadata
+import project.Internal.IR.Order_Descriptor.Order_Descriptor
+import project.Internal.IR.SQL_Expression.SQL_Expression
+import project.Internal.IR.Internal_Column.Internal_Column
+
+## PRIVATE
+make_offset (n : Integer) (colName: Internal_Column) (order_descriptors : Vector Order_Descriptor) (grouping_expressions : Vector SQL_Expression) -> SQL_Expression =
+    params = [SQL_Expression.Literal n.abs.to_text, colName.expression] + order_descriptors + grouping_expressions
+    metadata = Operation_Metadata.Row_Number_Metadata.Value grouping_expressions.length
+    lead_lag = if n<0 then "LAG" else "LEAD"
+    SQL_Expression.Operation lead_lag params metadata

distribution/lib/Standard/Microsoft/0.0.0-dev/src/Internal/SQLServer_Dialect.enso

@@ -292,6 +292,7 @@ type SQLServer_Dialect
             Feature.Join -> True
             Feature.Union -> True
             Feature.Aggregate -> True
+            Feature.Offset -> True
             _ -> False
 
     ## PRIVATE

distribution/lib/Standard/Table/0.0.0-dev/src/Table.enso

@@ -147,9 +147,10 @@ type Table
             Error.throw (Illegal_Argument.Error "Each column must be represented by a pair whose first element is the column name and the second element is a vector of elements that will constitute that column, or an existing column. Got: "+columns.to_text)
         cols = columns.map on_problems=No_Wrap.Value c->
             case c of
-                v : Vector ->
-                    if v.length != 2 then invalid_input_shape else
-                        Column.from_vector (v.at 0) (v.at 1) . java_column
+                v : Vector -> case v.length of
+                    2 -> Column.from_vector (v.at 0) (v.at 1) . java_column
+                    3 -> Column.from_vector (v.at 0) (v.at 1) (v.at 2) . java_column
+                    _ -> invalid_input_shape
                 col : Column -> col.java_column
                 _ -> invalid_input_shape
         Panic.recover Illegal_Argument <|