MySQL come interrogare il saldo corrente come saldo precedente

puoi usare row_number() da utilizzare per left join il tuo previous balance .

select t1.*, t2.PrevBalance from
    (select Date, PrevBalance, AddedAmount,
        row_number() over (order by Date asc) as rn 
    from tableA) t1    
left join 
    (select Date, PrevBalance, AddedAmount,
        row_number() over (order by Date asc) as rn 
    from tableA) t2 on t2.rn + 1 = t1.rn