/
select.go
48 lines (42 loc) · 935 Bytes
/
select.go
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package clause
type Select struct {
Columns []Column
Expressions []Expression
Distinct bool
}
func (s Select) Name() string {
return "SELECT"
}
func (s Select) Build(builder Builder) {
columnCount := len(s.Columns)
if columnCount > 0 {
if s.Distinct {
builder.WriteString("DISTINCT ")
}
for idx, column := range s.Columns {
if idx > 0 {
builder.WriteByte(',')
}
builder.WriteQuoted(column)
}
}
for idx, expr := range s.Expressions {
if columnCount > 0 || idx > 0 {
builder.WriteByte(',')
}
expr.Build(builder)
}
if columnCount == 0 && len(s.Expressions) == 0 {
builder.WriteByte('*')
}
}
func (s Select) MergeClause(clause *Clause) {
if v, ok := clause.Expression.(Select); ok {
if !s.Distinct && v.Distinct {
s.Distinct = v.Distinct
}
s.Expressions = append(v.Expressions, s.Expressions...)
s.Columns = append(v.Columns, s.Columns...)
}
clause.Expression = s
}