Derived tabled func

cmd/generate.go

@@ -76,8 +76,18 @@ func generate(scheamPath, outDir string) error {
 			return err
 		}
 	}
+
 	sb.WriteString(")")
 
+	sb.WriteString(`
+	func DerivedTable(tblName string, fromQry pgm.Query) pgm.Table {
+		t := pgm.Table{
+			Name:         tblName,
+			DerivedTable: fromQry,
+		}
+		return t
+}`)
+
 	// Format code before saving
 	code, err := formatGoCode(sb.String())
 	if err != nil {

pgm_field.go

@@ -131,6 +131,16 @@ func (f Field) IsNotNull() Conditioner {
 	return &Cond{Field: col, op: " IS NOT NULL", len: len(col) + 12}
 }
 
+// DateTrunc will truncate date or timestamp to specified level of precision
+//
+// Level values:
+//   - microseconds, milliseconds, second, minute, hour
+//   - day, week (Monday start), month, quarter, year
+//   - decade, century, millennium
+func (f Field) DateTrunc(level, as string) Field {
+	return Field("DATE_TRUNC('" + level + "', " + f.String() + ") AS " + as)
+}
+
 // EqualFold will use LOWER(column_name) = LOWER(val) for comparision
 func (f Field) EqFold(val string) Conditioner {
 	col := f.String()

playground/db/derived.go

@@ -1,11 +0,0 @@
-package db
-
-import "code.patial.tech/go/pgm"
-
-func DerivedTable(tblName string, fromQry pgm.Query) pgm.Table {
-	t := pgm.Table{
-		Name:         tblName,
-		DerivedTable: fromQry,
-	}
-	return t
-}

playground/db/schema.go

@@ -12,3 +12,11 @@ var (
 	Comment     = pgm.Table{Name: "comments", FieldCount: 5}
 	Employee    = pgm.Table{Name: "employees", FieldCount: 5}
 )
+
+func DerivedTable(tblName string, fromQry pgm.Query) pgm.Table {
+	t := pgm.Table{
+		Name:         tblName,
+		DerivedTable: fromQry,
+	}
+	return t
+}