What is the duty of an appellate court to uphold a judgment or order of the trial court?

"A judgment or order of the trial court is presumed correct, and must be upheld if it is supported by substantial evidence, no matter how slight it may be. [Citation.] Further, all evidence must be viewed in the light most favorable to the prevailing party, and all conflicts in evidence or in inferences must be resolved in favor of upholding the trial court's judgment or order. [Citations.] Where sufficiency of the evidence is questioned, the duty of an appellate court begins and ends with a determination that there is in the record evidence legally sufficient to support the judgment order. [Citation.]" (Schwartzman v. Wilshinsky (1996) 50 Cal.App.4th 619, 626.)