Function AddJoin

pkg/transform/joins.go:45–62

AddJoin returns a Rule that appends a JOIN clause to the SELECT statement. The join type is validated against the set of supported types; an error is returned for any unrecognised value. Parameters: - joinType: One of INNER, LEFT, RIGHT, FULL, CROSS, or NATURAL (case-insensitive) - table: Name of t

(joinType string, table string, condition ast.Expression)

// Returns an error for unrecognised join types or ErrUnsupportedStatement for
// non-SELECT statements.
func AddJoin(joinType string, table string, condition ast.Expression) Rule {
	return RuleFunc(func(stmt ast.Statement) error {
		upper := strings.ToUpper(joinType)
		if !validJoinTypes[upper] {
			return fmt.Errorf("AddJoin: unknown join type %q (valid: INNER, LEFT, RIGHT, FULL, CROSS, NATURAL)", joinType)
		}
		sel, err := getSelect(stmt, "AddJoin")
		if err != nil {
			return err
		}
		sel.Joins = append(sel.Joins, ast.JoinClause{
			Type:      upper,
			Right:     ast.TableReference{Name: table},
			Condition: condition,
		})
		return nil
	})
}

// RemoveJoin returns a Rule that removes all JOIN clauses whose right-hand table name
// or alias matches tableName (case-insensitive). If no matching JOIN exists the