有教无类的专栏

树形查询语句如下SELECT empno, ename, mgr, PRIOR empno AS prior_empno,LEVEL  FROM emp START WITH mgr IS NULLCONNECT BY PRIOR empno = mgr;EMPNOENAMEMGRPRIOR_EMPNO   LEV

with l as (select level as lv from dual connect by level <= 9),m as (select a.lv as lv_a, b.lv as lv_b, to_char(b.lv) || ' × ' || to_char(a.lv) || ' = ' || rpad(to_char(a

有人问  表   父id 子ID 知道  子值 ，怎么把所有的子都选出来 ，这个当然用树形查询就可以了。可他跟着来了一个db2那试下with语句吧WITH X(EMPNO,MGR,ENAME,LV) AS (SELECT EMPNO, MGR, ENAME, 1 AS LV FROM EMP WHERE MGR IS NULL UNION ALL SELE

教主 帮朋友问个问题  有个类似于撮合的系统随机取10个用户  要求他们的一个指标数之和等于100 这种需求能用sql搞定么？ 由于不

样例数据如下：CREATE OR REPLACE VIEW t AS (SELECT 'B' a, 'A' b, 2 n FROM dual UNION ALL SELECT 'C' a, 'A' b, 4 n FROM dual UNION ALL SELECT 'D' a, 'B' b, 3 n FROM dual UNION ALL SELECT 'E' a, 'B' b,

有学生提这个需求，这个太好实现了，肯定是没好好听课SELECT last_m + (LEVEL - 1) AS d FROM (SELECT add_months(trunc(SYSDATE, 'mm'), -1) last_m, trunc(SYSDATE, 'mm') m FROM dual)CONNECT BY LEVEL <= m

要求枚举给定时段内的季度信息，原数据模拟如下这种需求可以通过connect by 语句来分拆，只要计算出中间间隔的季度即可SELECT t.id, t.开始年, t.开始季度, t.结束年, t.结束季度, lv, to_char(d3, 'yyyy') AS 枚举年, to_char

有这样一个需求，对于各行数据要求 1+2 1+2+3 1+2+3+4 —– 2+3 2+3+4 —- 28+29 上面的1 2 3 是行号 我们以emp表为例WITH x0 AS (SELECT rownum AS rn, sal FROM (SELECT sal FROM emp ORDER BY sal))SELECT sal, dbms_aw.eval_number(s