chore(embedded/sql): improvements on SQL layer.

    - Allow selecting generic expressions;
    - Refactor FnCall implementation;
    - Add support for INSERT INTO SELECT statements;
    - Add more core builtin functions;

Signed-off-by: Stefano Scafiti <stefano.scafiti96@gmail.com>

embedded/document/engine.go

@@ -748,10 +748,10 @@ func (e *Engine) upsertDocuments(ctx context.Context, sqlTx *sql.SQLTx, collecti
 		ctx,
 		sqlTx,
 		[]sql.SQLStmt{
-			sql.NewUpserIntoStmt(
+			sql.NewUpsertIntoStmt(
 				collectionName,
 				colNames,
-				rows,
+				sql.NewValuesDataSource(rows),
 				isInsert,
 				nil,
 			),
@@ -879,7 +879,7 @@ func (e *Engine) ReplaceDocuments(ctx context.Context, username string, query *p
 	}
 
 	queryStmt := sql.NewSelectStmt(
-		[]sql.Selector{sql.NewColSelector(query.CollectionName, documentIdFieldName)},
+		[]sql.TargetEntry{{Exp: sql.NewColSelector(query.CollectionName, documentIdFieldName)}},
 		sql.NewTableRef(query.CollectionName, ""),
 		queryCondition,
 		generateSQLOrderByClauses(table, query.OrderBy),
@@ -982,7 +982,7 @@ func (e *Engine) GetDocuments(ctx context.Context, query *protomodel.Query, offs
 	}
 
 	op := sql.NewSelectStmt(
-		[]sql.Selector{sql.NewColSelector(query.CollectionName, DocumentBLOBField)},
+		[]sql.TargetEntry{{Exp: sql.NewColSelector(query.CollectionName, DocumentBLOBField)}},
 		sql.NewTableRef(query.CollectionName, ""),
 		queryCondition,
 		generateSQLOrderByClauses(table, query.OrderBy),
@@ -1023,7 +1023,7 @@ func (e *Engine) CountDocuments(ctx context.Context, query *protomodel.Query, of
 	}
 
 	ds := sql.NewSelectStmt(
-		[]sql.Selector{sql.NewColSelector(query.CollectionName, table.Cols()[0].Name())},
+		[]sql.TargetEntry{{Exp: sql.NewColSelector(query.CollectionName, table.Cols()[0].Name())}},
 		sql.NewTableRef(query.CollectionName, ""),
 		queryCondition,
 		generateSQLOrderByClauses(table, query.OrderBy),
@@ -1032,7 +1032,7 @@ func (e *Engine) CountDocuments(ctx context.Context, query *protomodel.Query, of
 	)
 
 	op := sql.NewSelectStmt(
-		[]sql.Selector{sql.NewAggColSelector(sql.COUNT, query.CollectionName, "*")},
+		[]sql.TargetEntry{{Exp: sql.NewAggColSelector(sql.COUNT, query.CollectionName, "*")}},
 		ds,
 		nil,
 		nil,

embedded/sql/aggregated_values.go

@@ -102,6 +102,10 @@ func (v *CountValue) reduce(tx *SQLTx, row *Row, implicitTable string) (TypedVal
 	return nil, ErrUnexpected
 }
 
+func (v *CountValue) selectors() []Selector {
+	return nil
+}
+
 func (v *CountValue) reduceSelectors(row *Row, implicitTable string) ValueExp {
 	return nil
 }
@@ -198,6 +202,10 @@ func (v *SumValue) reduce(tx *SQLTx, row *Row, implicitTable string) (TypedValue
 	return nil, ErrUnexpected
 }
 
+func (v *SumValue) selectors() []Selector {
+	return nil
+}
+
 func (v *SumValue) reduceSelectors(row *Row, implicitTable string) ValueExp {
 	return v
 }
@@ -301,6 +309,10 @@ func (v *MinValue) reduce(tx *SQLTx, row *Row, implicitTable string) (TypedValue
 	return nil, ErrUnexpected
 }
 
+func (v *MinValue) selectors() []Selector {
+	return nil
+}
+
 func (v *MinValue) reduceSelectors(row *Row, implicitTable string) ValueExp {
 	return nil
 }
@@ -404,6 +416,10 @@ func (v *MaxValue) reduce(tx *SQLTx, row *Row, implicitTable string) (TypedValue
 	return nil, ErrUnexpected
 }
 
+func (v *MaxValue) selectors() []Selector {
+	return nil
+}
+
 func (v *MaxValue) reduceSelectors(row *Row, implicitTable string) ValueExp {
 	return nil
 }
@@ -516,6 +532,10 @@ func (v *AVGValue) reduce(tx *SQLTx, row *Row, implicitTable string) (TypedValue
 	return nil, ErrUnexpected
 }
 
+func (v *AVGValue) selectors() []Selector {
+	return nil
+}
+
 func (v *AVGValue) reduceSelectors(row *Row, implicitTable string) ValueExp {
 	return nil
 }

embedded/sql/engine.go

@@ -658,7 +658,6 @@ func (e *Engine) InferParameters(ctx context.Context, tx *SQLTx, sql string) (pa
 	if err != nil {
 		return nil, fmt.Errorf("%w: %v", ErrParsingError, err)
 	}
-
 	return e.InferParametersPreparedStmts(ctx, tx, stmts)
 }