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  • 莫名其妙的Explain Plan

    两张表的建表语句:

    CREATE TABLE hy_emp
    (
    empno NUMBER(8,0) not null primary key,
    ename NVARCHAR2(60) not null,
    deptno NUMBER(8,0) not null,
    sal NUMBER(10,0) DEFAULT 0 not null 
    )
    
    
    CREATE TABLE hy_dept
    (
    deptno NUMBER(8,0) not null primary key,
    dname NVARCHAR2(60) not null
    )

    插值语句:

    insert into hy_dept(deptno,dname) values('1','Hr');
    insert into hy_dept(deptno,dname) values('2','Dev');
    insert into hy_dept(deptno,dname) values('3','Qa');
    insert into hy_dept(deptno,dname) values('4','Sales');
    insert into hy_dept(deptno,dname) values('5','Mng');
    
    insert into hy_emp(empno,ename,deptno,sal) values('1','Andy','1',1000);
    insert into hy_emp(empno,ename,deptno,sal) values('2','Bill','2',2000);
    insert into hy_emp(empno,ename,deptno,sal) values('3','Cindy','3',3000);
    insert into hy_emp(empno,ename,deptno,sal) values('4','Douglas','4',4000);
    insert into hy_emp(empno,ename,deptno,sal) values('5','Edinburg','5',5000);
    insert into hy_emp(empno,ename,deptno,sal) values('6','Felix','1',6000);
    insert into hy_emp(empno,ename,deptno,sal) values('7','Hellen','2',7000);
    insert into hy_emp(empno,ename,deptno,sal) values('8','Isis','3',8000);
    insert into hy_emp(empno,ename,deptno,sal) values('9','Jean','4',9000);
    insert into hy_emp(empno,ename,deptno,sal) values('10','King','5',10000);
    insert into hy_emp(empno,ename,deptno,sal) values('11','Mac','1',11000);

    单表的Explain plan还好,两张表的实在让人莫名其妙:

    留待日后分辨吧。

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  • 原文地址:https://www.cnblogs.com/heyang78/p/12122701.html
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