Order by sql serialization simplified.

sqlbuilder/alias.go

@@ -14,7 +14,7 @@ func NewAlias(expression expression, alias string) *Alias {
 
 func (a *Alias) serializeForProjection(out *queryData) error {
 
-	err := a.expression.serialize(out)
+	err := a.expression.serializeForProjection(out)
 
 	if err != nil {
 		return err

sqlbuilder/clause.go

@@ -15,7 +15,6 @@ type queryData struct {
 	args []interface{}
 
 	statementType int
-	clauseType    int
 }
 
 const (
@@ -26,43 +25,29 @@ const (
 	set_statement
 )
 
-const (
-	projection_clause = iota
-	where_clause
-	order_by_clause
-	group_by_clause
-	having_clause
-)
-
 func (q *queryData) WriteProjection(projections []projection) error {
-	q.clauseType = projection_clause
 	return serializeProjectionList(projections, q)
 }
 
 func (q *queryData) WriteWhere(where expression) error {
-	q.clauseType = where_clause
 	q.WriteString(" WHERE ")
 	return where.serialize(q)
 }
 
 func (q *queryData) WriteGroupBy(groupBy []groupByClause) error {
-	q.clauseType = group_by_clause
 	q.WriteString(" GROUP BY ")
 
 	return serializeGroupByClauseList(groupBy, q)
 }
 
 func (q *queryData) WriteOrderBy(orderBy []orderByClause) error {
-	q.clauseType = order_by_clause
 	q.WriteString(" ORDER BY ")
 	return serializeOrderByClauseList(orderBy, q)
 }
 
 func (q *queryData) WriteHaving(having expression) error {
-	q.clauseType = having_clause
 	q.WriteString(" HAVING ")
 	return having.serialize(q)
-
 }
 
 func (q *queryData) Write(data []byte) {

sqlbuilder/column.go

@@ -77,20 +77,33 @@ func (c *baseColumn) DefaultAlias() projection {
 	return c.AS(c.tableName + "." + c.name)
 }
 
-func (c baseColumn) serialize(out *queryData) error {
-
-	setOrderBy := out.statementType == set_statement && out.clauseType == order_by_clause
-
-	if setOrderBy {
+func (c *baseColumn) serializeAsOrderBy(out *queryData) error {
+	if out.statementType == set_statement {
+		// set statement (UNION, EXCEPT ...) can reference only select projections in order by clause
 		out.WriteString(`"`)
+
+		if c.tableName != "" {
+			out.WriteString(c.tableName)
+			out.WriteString(".")
+		}
+
+		out.WriteString(c.name)
+
+		out.WriteString(`"`)
+
+		return nil
 	}
 
+	return c.serialize(out)
+}
+
+func (c baseColumn) serialize(out *queryData) error {
 	if c.tableName != "" {
 		out.WriteString(c.tableName)
 		out.WriteString(".")
 	}
 
-	wrapColumnName := strings.Contains(c.name, ".") && !setOrderBy
+	wrapColumnName := strings.Contains(c.name, ".")
 
 	if wrapColumnName {
 		out.WriteString(`"`)
@@ -102,9 +115,5 @@ func (c baseColumn) serialize(out *queryData) error {
 		out.WriteString(`"`)
 	}
 
-	if setOrderBy {
-		out.WriteString(`"`)
-	}
-
 	return nil
 }

sqlbuilder/expression.go

@@ -9,6 +9,7 @@ type expression interface {
 	clause
 	projection
 	groupByClause
+	orderByClause
 
 	IN(subQuery selectStatement) boolExpression
 	NOT_IN(subQuery selectStatement) boolExpression
@@ -60,6 +61,10 @@ func (e *expressionInterfaceImpl) serializeForProjection(out *queryData) error {
 	return e.parent.serialize(out)
 }
 
+func (e *expressionInterfaceImpl) serializeAsOrderBy(out *queryData) error {
+	return e.parent.serialize(out)
+}
+
 // Representation of binary operations (e.g. comparisons, arithmetic)
 type binaryExpression struct {
 	lhs, rhs expression

sqlbuilder/order_by_clause.go

@@ -3,28 +3,20 @@ package sqlbuilder
 import "github.com/dropbox/godropbox/errors"
 
 type orderByClause interface {
-	clause
-	isOrderByClauseType()
-}
-
-type isOrderByClause struct {
-}
-
-func (o *isOrderByClause) isOrderByClauseType() {
+	serializeAsOrderBy(out *queryData) error
 }
 
 type orderByClauseImpl struct {
-	isOrderByClause
 	expression expression
 	ascent     bool
 }
 
-func (o *orderByClauseImpl) serialize(out *queryData) error {
+func (o *orderByClauseImpl) serializeAsOrderBy(out *queryData) error {
 	if o.expression == nil {
 		return errors.Newf("nil orderBy by clause.")
 	}
 
-	if err := o.expression.serialize(out); err != nil {
+	if err := o.expression.serializeAsOrderBy(out); err != nil {
 		return err
 	}
 

sqlbuilder/utils.go

@@ -14,7 +14,7 @@ func serializeOrderByClauseList(orderByClauses []orderByClause, out *queryData)
 			out.WriteString(", ")
 		}
 
-		err := value.serialize(out)
+		err := value.serializeAsOrderBy(out)
 
 		if err != nil {
 			return err