(a) When from any cause the judge of the superior court or any city court is disqualified from presiding in any civil case and has failed to procure the services of a judge to try the case, then the parties litigant, by consent, may select any attorney of this state to preside in the case; the attorney so selected, when the consent is entered on the minutes, shall exercise all the functions of a judge in that case. Any senior judge of the superior courts may likewise be selected.
(b) In all cases mentioned in subsection (a) of this Code section, when the case or cases are reached in their order on the docket without an agreement by the parties as to the selection of an attorney to preside as judge, it shall be the duty of the clerk of the superior court or in his absence, the deputy clerk to select some competent attorney practicing in that court, who shall likewise have authority and preside in the case as aforesaid. Any senior judge of the superior courts may likewise be
selected.