Add support for INTERSECT and EXCEPT statements.

sqlbuilder/set_statement.go

@@ -0,0 +1,146 @@
+package sqlbuilder
+
+import (
+	"database/sql"
+	"github.com/dropbox/godropbox/errors"
+	"github.com/sub0zero/go-sqlbuilder/types"
+)
+
+const (
+	union     = "UNION"
+	intersect = "INTERSECT"
+	except    = "EXCEPT"
+)
+
+type SetStatement interface {
+	Statement
+
+	ORDER_BY(clauses ...OrderByClause) SetStatement
+	LIMIT(limit int64) SetStatement
+	OFFSET(offset int64) SetStatement
+}
+
+func UNION(selects ...SelectStatement) SetStatement {
+	return newSetStatementImpl(union, false, selects...)
+}
+
+func UNION_ALL(selects ...SelectStatement) SetStatement {
+	return newSetStatementImpl(union, true, selects...)
+}
+
+func INTERSECT(selects ...SelectStatement) SetStatement {
+	return newSetStatementImpl(intersect, false, selects...)
+}
+
+func INTERSECT_ALL(selects ...SelectStatement) SetStatement {
+	return newSetStatementImpl(intersect, true, selects...)
+}
+
+func EXCEPT(selects ...SelectStatement) SetStatement {
+	return newSetStatementImpl(except, false, selects...)
+}
+
+func EXCEPT_ALL(selects ...SelectStatement) SetStatement {
+	return newSetStatementImpl(except, true, selects...)
+}
+
+// Similar to selectStatementImpl, but less complete
+type setStatementImpl struct {
+	operator      string
+	selects       []SelectStatement
+	order         *listClause
+	limit, offset int64
+	// True if results of the union should be deduped.
+	all bool
+}
+
+func newSetStatementImpl(operator string, all bool, selects ...SelectStatement) *setStatementImpl {
+	return &setStatementImpl{
+		operator: operator,
+		selects:  selects,
+		limit:    -1,
+		offset:   -1,
+		all:      all,
+	}
+}
+
+func (us *setStatementImpl) ORDER_BY(clauses ...OrderByClause) SetStatement {
+
+	us.order = newOrderByListClause(clauses...)
+	return us
+}
+
+func (us *setStatementImpl) LIMIT(limit int64) SetStatement {
+	us.limit = limit
+	return us
+}
+
+func (us *setStatementImpl) OFFSET(offset int64) SetStatement {
+	us.offset = offset
+	return us
+}
+
+func (us *setStatementImpl) Serialize(out *queryData, options ...serializeOption) error {
+	if len(us.selects) == 0 {
+		return errors.Newf("UNION statement must have at least one SELECT")
+	}
+
+	out.WriteString("(")
+
+	for i, selectStmt := range us.selects {
+		if i > 0 {
+			out.WriteString(" " + us.operator + " ")
+
+			if us.all {
+				out.WriteString(" ALL ")
+			}
+		}
+
+		err := selectStmt.Serialize(out, options...)
+
+		if err != nil {
+			return err
+		}
+	}
+
+	out.WriteString(")")
+
+	if us.order != nil {
+		out.WriteString(" ORDER BY ")
+		if err := us.order.Serialize(out, NO_TABLE_NAME); err != nil {
+			return err
+		}
+	}
+
+	if us.limit >= 0 {
+		out.WriteString(" LIMIT ")
+		out.InsertArgument(us.limit)
+	}
+
+	if us.offset >= 0 {
+		out.WriteString(" OFFSET ")
+		out.InsertArgument(us.offset)
+	}
+
+	return nil
+}
+
+func (us *setStatementImpl) Sql() (query string, args []interface{}, err error) {
+	queryData := &queryData{}
+
+	err = us.Serialize(queryData)
+
+	if err != nil {
+		return
+	}
+
+	return queryData.buff.String(), queryData.args, nil
+}
+
+func (s *setStatementImpl) Query(db types.Db, destination interface{}) error {
+	return Query(s, db, destination)
+}
+
+func (u *setStatementImpl) Execute(db types.Db) (res sql.Result, err error) {
+	return Execute(u, db)
+}