avoid duplicate comment opts (#64)

* avoid duplicate comment opts

* correct compare 2 list elements

Author: sunary

element/column.go

@@ -186,6 +186,7 @@ func (c Column) pkDefinition(isPrev bool) (string, bool) {
 	strSql := " " + c.typeDefinition(isPrev)
 
 	isPrimaryKey := false
+	hasComment := false
 	for _, opt := range attr.Options {
 		if opt.Tp == ast.ColumnOptionPrimaryKey {
 			isPrimaryKey = true
@@ -248,7 +249,14 @@ func (c Column) pkDefinition(isPrev bool) (string, bool) {
 		if opt.Tp == ast.ColumnOptionDefaultValue {
 			optStr = strings.ReplaceAll(optStr, "DEFAULT _UTF8MB4", "DEFAULT ")
 		}
-		strSql += " " + optStr
+
+		if !hasComment {
+			strSql += " " + optStr
+		}
+
+		if opt.Tp == ast.ColumnOptionComment {
+			hasComment = true
+		}
 	}
 
 	return strSql, isPrimaryKey

element/table.go

@@ -262,18 +262,40 @@ func (t Table) getIndexForeignKey(fkName string) int {
 }
 
 func hasChangedMysqlOptions(new, old []*ast.ColumnOption) bool {
-	if len(new) != len(old) {
+	optNew := make([]*ast.ColumnOption, 0, len(new))
+	hasComment := false
+	for _, v := range new {
+		if !hasComment {
+			optNew = append(optNew, v)
+		}
+		if v.Tp == ast.ColumnOptionComment {
+			hasComment = true
+		}
+	}
+
+	optOld := make([]*ast.ColumnOption, 0, len(old))
+	hasComment = false
+	for _, v := range old {
+		if !hasComment {
+			optOld = append(optOld, v)
+		}
+		if v.Tp == ast.ColumnOptionComment {
+			hasComment = true
+		}
+	}
+
+	if len(optNew) != len(optOld) {
 		return true
 	}
 
 	mNew := map[ast.ColumnOptionType]int{}
-	for i := range old {
-		mNew[old[i].Tp] += 1
+	for i := range optNew {
+		mNew[optNew[i].Tp] += 1
 	}
 
 	mOld := map[ast.ColumnOptionType]int{}
-	for i := range old {
-		mOld[old[i].Tp] += 1
+	for i := range optOld {
+		mOld[optOld[i].Tp] += 1
 	}
 
 	for k, v := range mOld {