trunc(dbms_RANDOM.VALUE(1,71)) 如何限制一条

如果您想要在SQL语句中使用`trunc(dbms_random.value(1,71))`来生成一个随机数，并且需要将该随机数限制为一个固定值，可以将该随机数作为子查询的结果，然后在外层查询中使用`WHERE`子句来限制结果集。例如，如果您需要将该随机数限制为50，可以使用如下SQL语句：

SELECT trunc(dbms_random.value(1,71)) as rand_num
FROM dual
WHERE trunc(dbms_random.value(1,71)) = 50;

这里使用了`dual`表作为子查询的来源，同时使用`WHERE`子句来过滤结果集，只返回随机数等于50的记录。如果您需要返回多条记录，可以使用`UNION ALL`来连接多个子查询。例如，如果您需要返回10条随机数等于50的记录，可以使用如下SQL语句：

SELECT trunc(dbms_random.value(1,71)) as rand_num
FROM dual
WHERE trunc(dbms_random.value(1,71)) = 50
UNION ALL
SELECT trunc(dbms_random.value(1,71)) as rand_num
FROM dual
WHERE trunc(dbms_random.value(1,71)) = 50
UNION ALL
SELECT trunc(dbms_random.value(1,71)) as rand_num
FROM dual
WHERE trunc(dbms_random.value(1,71)) = 50
UNION ALL
SELECT trunc(dbms_random.value(1,71)) as rand_num
FROM dual
WHERE trunc(dbms_random.value(1,71)) = 50
UNION ALL
SELECT trunc(dbms_random.value(1,71)) as rand_num
FROM dual
WHERE trunc(dbms_random.value(1,71)) = 50
UNION ALL
SELECT trunc(dbms_random.value(1,71)) as rand_num
FROM dual
WHERE trunc(dbms_random.value(1,71)) = 50
UNION ALL
SELECT trunc(dbms_random.value(1,71)) as rand_num
FROM dual
WHERE trunc(dbms_random.value(1,71)) = 50
UNION ALL
SELECT trunc(dbms_random.value(1,71)) as rand_num
FROM dual
WHERE trunc(dbms_random.value(1,71)) = 50
UNION ALL
SELECT trunc(dbms_random.value(1,71)) as rand_num
FROM dual
WHERE trunc(dbms_random.value(1,71)) = 50
UNION ALL
SELECT trunc(dbms_random.value(1,71)) as rand_num
FROM dual
WHERE trunc(dbms_random.value(1,71)) = 50;

这里使用了10个子查询来生成10条随机数等于50的记录。