diff --git a/source_builder.go b/source_builder.go
index d18da67..ce4d4e2 100644
--- a/source_builder.go
+++ b/source_builder.go
@@ -80,7 +80,6 @@ func (sb *SourceBuilder) Join(join JOIN) *SourceBuilder {
 	}
 
 	x := SourceX{}
-
 	*sb.xs = append(*sb.xs, &x)
 	sb.x = &x
 
@@ -90,7 +89,9 @@ func (sb *SourceBuilder) Join(join JOIN) *SourceBuilder {
 	return sb
 }
 
-func (sb *SourceBuilder) Sub(sub *BuilderX) *SourceBuilder {
-	sb.x.sub = sub
+func (sb *SourceBuilder) Sub(sub func(sub *BuilderX)) *SourceBuilder {
+	x := new(BuilderX)
+	sb.x.sub = x
+	sub(x)
 	return sb
 }
diff --git a/source_builder_optimization.go b/source_builder_optimization.go
index 5f96576..6ccf035 100644
--- a/source_builder_optimization.go
+++ b/source_builder_optimization.go
@@ -34,7 +34,9 @@ func (x *BuilderX) optimizeSourceBuilder() {
 	}
 
 	x.removeSourceBuilder(x.sxs, func(useds *[]*SourceX, ele *SourceX, i int) bool {
-
+		if i == 0 {
+			return false
+		}
 		if ele.sub != nil && (ele.join != nil && !strings.Contains(ele.join.join, "LEFT")) {
 			return false
 		}
diff --git a/to_source_sql_by_builder.go b/to_source_sql_by_builder.go
index bcbf9f2..6c2f1c5 100644
--- a/to_source_sql_by_builder.go
+++ b/to_source_sql_by_builder.go
@@ -33,36 +33,36 @@ func (built *Built) toSourceSqlBySql(bp *strings.Builder) bool {
 	return false
 }
 
-func (built *Built) toSourceSqlByBuilder(vs *[]interface{}, sb *SourceX, bp *strings.Builder) {
-	if sb.join != nil { //JOIN
+func (built *Built) toSourceSqlByBuilder(vs *[]interface{}, sx *SourceX, bp *strings.Builder) {
+	if sx.join != nil { //JOIN
 		bp.WriteString(SPACE)
-		bp.WriteString(sb.join.join)
+		bp.WriteString(sx.join.join)
 		bp.WriteString(SPACE)
 	}
-	if sb.po != nil {
-		bp.WriteString(sb.po.TableName())
-	} else if sb.sub != nil {
-		dataSql, _ := sb.sub.Build().sqlData(vs, nil)
+	if sx.po != nil {
+		bp.WriteString(sx.po.TableName())
+	} else if sx.sub != nil {
+		dataSql, _ := sx.sub.Build().sqlData(vs, nil)
 		bp.WriteString(BEGIN_SUB)
 		bp.WriteString(dataSql)
 		bp.WriteString(END_SUB)
 	}
-	if sb.alia != "" {
+	if sx.alia != "" {
 		bp.WriteString(SPACE)
-		bp.WriteString(sb.alia)
+		bp.WriteString(sx.alia)
 	}
-	if sb.join != nil && sb.join.on != nil { //ON
+	if sx.join != nil && sx.join.on != nil { //ON
 
-		if sb.join.on.orUsingKey != "" {
+		if sx.join.on.orUsingKey != "" {
 			bp.WriteString(USING_SCRIPT_LEFT)
-			bp.WriteString(sb.join.on.orUsingKey)
+			bp.WriteString(sx.join.on.orUsingKey)
 			bp.WriteString(END_SUB)
-		} else if sb.s != "" {
+		} else if sx.s != "" {
 			bp.WriteString(SPACE)
-			bp.WriteString(sb.s)
+			bp.WriteString(sx.s)
 		} else {
 			bp.WriteString(ON_SCRIPT)
-			built.toConditionSql(sb.join.on.bbs, bp, vs, nil)
+			built.toConditionSql(sx.join.on.bbs, bp, vs, nil)
 		}
 	}
 }