“通用” SQL方式:
SELECt table_1.custno,table_2.qty,table_2.descr FROM table_1, table_2 WHERe table_2.id = (SELECt TOP 1 id FROM table_2 WHERe custno = table_1.custno ORDER BY qty )
SQL 2008方式(可能更快):
SELECt custno, qty, descr FROM(SELECt custno, qty, descr, ROW_NUMBER() OVER (PARTITION BY custno ORDER BY qty) RowNum FROM table_2) AWHERe RowNum = 1