package clause // From from clause type From struct { Tables []Table Joins []Join } type JoinType string const ( CrossJoin JoinType = "CROSS" InnerJoin = "INNER" LeftJoin = "LEFT" RightJoin = "RIGHT" ) // Join join clause for from type Join struct { Type JoinType Table Table ON Where Using []string } // Name from clause name func (from From) Name() string { return "FROM" } // Build build from clause func (from From) Build(builder Builder) { if len(from.Tables) > 0 { for idx, table := range from.Tables { if idx > 0 { builder.WriteByte(',') } builder.WriteQuoted(table) } } else { builder.WriteQuoted(currentTable) } for _, join := range from.Joins { builder.WriteByte(' ') join.Build(builder) } } func (join Join) Build(builder Builder) { if join.Type != "" { builder.WriteString(string(join.Type)) builder.WriteByte(' ') } builder.WriteString("JOIN ") builder.WriteQuoted(join.Table) if len(join.ON.Exprs) > 0 { builder.WriteString(" ON ") join.ON.Build(builder) } else if len(join.Using) > 0 { builder.WriteString(" USING (") for idx, c := range join.Using { if idx > 0 { builder.WriteByte(',') } builder.WriteQuoted(c) } builder.WriteByte(')') } } // MergeClause merge from clause func (from From) MergeClause(clause *Clause) { if v, ok := clause.Expression.(From); ok { from.Tables = append(v.Tables, from.Tables...) from.Joins = append(v.Joins, from.Joins...) } clause.Expression = from }