MySQL refactor.

mysql/set_statement.go

@@ -0,0 +1,104 @@
+package mysql
+
+import "github.com/go-jet/jet/internal/jet"
+
+// UNION effectively appends the result of sub-queries(select statements) into single query.
+// It eliminates duplicate rows from its result.
+func UNION(lhs, rhs jet.StatementWithProjections, selects ...jet.StatementWithProjections) SetStatement {
+	return newSetStatementImpl(Union, false, toSelectList(lhs, rhs, selects...))
+}
+
+// UNION_ALL effectively appends the result of sub-queries(select statements) into single query.
+// It does not eliminates duplicate rows from its result.
+func UNION_ALL(lhs, rhs jet.StatementWithProjections, selects ...jet.StatementWithProjections) SetStatement {
+	return newSetStatementImpl(Union, true, toSelectList(lhs, rhs, selects...))
+}
+
+type SetStatement interface {
+	SetOperators
+
+	ORDER_BY(orderByClauses ...jet.OrderByClause) SetStatement
+
+	LIMIT(limit int64) SetStatement
+	OFFSET(offset int64) SetStatement
+
+	AsTable(alias string) SelectTable
+}
+
+type SetStatementFinal interface {
+}
+
+type SetOperators interface {
+	jet.Statement
+	jet.HasProjections
+	jet.IExpression
+
+	UNION(rhs SelectStatement) SetStatement
+	UNION_ALL(rhs SelectStatement) SetStatement
+}
+
+type setOperatorsImpl struct {
+	parent SetOperators
+}
+
+func (s *setOperatorsImpl) UNION(rhs SelectStatement) SetStatement {
+	return UNION(s.parent, rhs)
+}
+
+func (s *setOperatorsImpl) UNION_ALL(rhs SelectStatement) SetStatement {
+	return UNION_ALL(s.parent, rhs)
+}
+
+type setStatementImpl struct {
+	jet.ExpressionStatementImpl
+
+	setOperatorsImpl
+
+	setOperator jet.ClauseSetStmtOperator
+}
+
+func newSetStatementImpl(operator string, all bool, selects []jet.StatementWithProjections) SetStatement {
+	newSetStatement := &setStatementImpl{}
+	newSetStatement.ExpressionStatementImpl.StatementImpl = jet.NewStatementImpl(Dialect, jet.SetStatementType, newSetStatement,
+		&newSetStatement.setOperator)
+	newSetStatement.ExpressionStatementImpl.ExpressionInterfaceImpl.Parent = newSetStatement
+
+	newSetStatement.setOperator.Operator = operator
+	newSetStatement.setOperator.All = all
+	newSetStatement.setOperator.Selects = selects
+	newSetStatement.setOperator.Limit.Count = -1
+	newSetStatement.setOperator.Offset.Count = -1
+
+	newSetStatement.setOperatorsImpl.parent = newSetStatement
+
+	newSetStatement.Clauses = []jet.Clause{&newSetStatement.setOperator}
+
+	return newSetStatement
+}
+
+func (s *setStatementImpl) ORDER_BY(orderByClauses ...jet.OrderByClause) SetStatement {
+	s.setOperator.OrderBy.List = orderByClauses
+	return s
+}
+
+func (s *setStatementImpl) LIMIT(limit int64) SetStatement {
+	s.setOperator.Limit.Count = limit
+	return s
+}
+
+func (s *setStatementImpl) OFFSET(offset int64) SetStatement {
+	s.setOperator.Offset.Count = offset
+	return s
+}
+
+func (s *setStatementImpl) AsTable(alias string) SelectTable {
+	return newSelectTable(s, alias)
+}
+
+const (
+	Union = "UNION"
+)
+
+func toSelectList(lhs, rhs jet.StatementWithProjections, selects ...jet.StatementWithProjections) []jet.StatementWithProjections {
+	return append([]jet.StatementWithProjections{lhs, rhs}, selects...)
+}