From 37bbebf1d105577945bdffeab38a94af3d155406 Mon Sep 17 00:00:00 2001 From: xiangwbs Date: Wed, 13 Dec 2017 20:11:42 +0800 Subject: [PATCH] =?UTF-8?q?=E4=BF=AE=E6=94=B9sql=E7=A4=BA=E4=BE=8B?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- .../src/main/java/com/xwbing/demo/oracle/day02.sql | 7 ++++--- .../src/main/java/com/xwbing/demo/oracle/day03.sql | 1 + 2 files changed, 5 insertions(+), 3 deletions(-) diff --git a/boot-service/src/main/java/com/xwbing/demo/oracle/day02.sql b/boot-service/src/main/java/com/xwbing/demo/oracle/day02.sql index 4635873..df509a3 100644 --- a/boot-service/src/main/java/com/xwbing/demo/oracle/day02.sql +++ b/boot-service/src/main/java/com/xwbing/demo/oracle/day02.sql @@ -152,13 +152,14 @@ NULL的运算 null与字符串连接等于什么都没做 null与数字运算结果还是null 查看每个员工的收入？ -SELECT ENAME,SAL,COMM,SAL+COMM FROM EMP_XWBING; +SELECT ENAME,SAL,COMM FROM EMP_XWBING; NVL(P1,P1) 若p1为null，函数返回p2. 若不为null，函数返回p1自身。所以该函数的作用是将null替代换为非null值 查看每个员工的收入？ -SELECT ENAME,SAL,COMM,SAL+nvl(COMM,0) FROM EMP_XWBING; +SELECT ENAME,SAL,nvl(COMM,0) FROM EMP_XWBING; +SELECT ENAME,SAL,IFNULL(COMM,0) FROM EMP_XWBING;//MYSQL NVL2(P1,P2,P3) 若p1不为null值为p2，p1为null值为p3 查看每个员工的奖金情况？ SELECT ENAME,SAL,nvl2(COMM,'有奖金','无奖金') FROM EMP_XWBING; - +SELECT ENAME,SAL,IF(ISNULL(COMM),'无奖金','有奖金') FROM EMP_XWBING;//MYSQL isnull(字段) true返回1 diff --git a/boot-service/src/main/java/com/xwbing/demo/oracle/day03.sql b/boot-service/src/main/java/com/xwbing/demo/oracle/day03.sql index d017f4e..6e08d3f 100644 --- a/boot-service/src/main/java/com/xwbing/demo/oracle/day03.sql +++ b/boot-service/src/main/java/com/xwbing/demo/oracle/day03.sql @@ -54,6 +54,7 @@ desc：降序 select ename ,sal from emp_xwbing order by sal; select ename ,sal,deptno from emp_xwbing order by deptno,sal desc; select ename from emp_xwbing order by ename; +order by field(字段,'',''); 聚合函数又称多行函数：用来统计结果的