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1. This error may occur when a SINGLE SELECT statement is executed and more than one row complies with the search condition.
2. This error can also occur when a subquery specified in a comparison predicate or a SET UPDATE clause of an UPDATE statement is executed and more than one row complies with the search condition.
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1. The <SINGLE SELECT statement> can be replaced with a QUERY statement and a sequence of FETCH statements; or it can be ensured that at most one row complies with the conditions by expanding the <search condition>.
2. You can replace the comparison predicate with a quantity comparison predicate. You can try to change the subquery by specifying DISTINCT or expanding the search condition so that the subquery contains one row as the result at most.