Refactor parsing & select order by impl (#6)

Reviewed-on: #6

schema/constraint.go

@@ -3,14 +3,16 @@ package schema
 import (
 	"errors"
 	"strings"
+
+	"git.gdulai.com/gdulai/simpleorm/util"
 )
 
 type Constraint struct {
-	Name       string
-	Type       string
-	Columns    []Column
-	RefTable   *Table
-	RefColumns []Column
+	Name        string
+	Type        string
+	Columns     []Column
+	RefTypeName string
+	RefColumns  []Column
 }
 
 func (c *Constraint) GetDDL() (string, error) {
@@ -26,7 +28,9 @@ func (c *Constraint) GetDDL() (string, error) {
 
 func (c *Constraint) getPkDDL() string {
 	var ddl strings.Builder
-	ddl.WriteString("CONSTRAINT " + c.Name + " PRIMARY KEY(")
+	ddl.WriteString("CONSTRAINT ")
+	ddl.WriteString(c.Name)
+	ddl.WriteString(" PRIMARY KEY(")
 	for i, col := range c.Columns {
 		if i != 0 {
 			ddl.WriteString(", ")
@@ -39,7 +43,9 @@ func (c *Constraint) getPkDDL() string {
 
 func (c *Constraint) getFkDDL() string {
 	var ddl strings.Builder
-	ddl.WriteString("CONSTRAINT " + c.Name + " FOREIGN KEY(")
+	ddl.WriteString("CONSTRAINT ")
+	ddl.WriteString(c.Name)
+	ddl.WriteString(" FOREIGN KEY(")
 
 	for i, col := range c.Columns {
 		if i != 0 {
@@ -47,7 +53,10 @@ func (c *Constraint) getFkDDL() string {
 		}
 		ddl.WriteString(col.Name)
 	}
-	ddl.WriteString(") REFERENCES " + c.RefTable.Name + "(")
+
+	ddl.WriteString(") REFERENCES ")
+	ddl.WriteString(util.CamelToSnake(c.RefTypeName))
+	ddl.WriteString("(")
 
 	for i, col := range c.RefColumns {
 		if i != 0 {