SQL joins are covered in more detail in a later lesson. * Basic SELECT Statement In its simplest form, a SELECT statement must include the following: A SELECT clause, which specifies the columns to be displayed A FROM clause, which identifies the table containing the columns that are listed ...
06_qp_joinsppt 系统标签: nljsortiosclusteredoperatortuple CPS216:AdvancedDatabase Systems Notes06:QueryExecution (SortandJoinoperators) ShivnathBabu parse Queryrewriting Physicalplangeneration execute result SQLquery parsetree logicalqueryplanstatistics physicalqueryplan QueryProcessing-Inclassorder 2;16.1 3;...
e.g., “insert on Sells.” Condition : (tests whether the trigger should run) Any SQL Boolean-valued expression Action : (procedure executed when trigger runs) Any SQL statements Example: Instead of using
Using Outer Joins to Return Records with No Direct Match The missing rows can be returned if an outer join operator is used in the join condition. The operator is a plus sign enclosed in parentheses (+), and it is placed on the “side” of the join that is deficient in information. ...
1.Insertatupleortuples.2.Deleteatupleortuples.3.Updatethevalue(s)ofanexistingtupleortuples.1 第1页/共45页 Insertion •Toinsertasingletuple:INSERTINTO<relation> VALUES(<listofvalues>);•Example:addSydneyGreenstreettothelistofstarsofTheMalteseFalcon.INSERTINTOStarsIn VALUES(‘TheMalteseFalcon’,...
1 •关系数据库 –关系数据结构及形式化定义 •域、笛卡尔积、关系、主码、外码、关系模式 –关系代数运算符 –使用关系代数描述用户查询 •SQL语言 –SQL语言的特点 –SQL命令及使用 •关系数据理论 –函数依赖等基本概念 –1NF、2NF、3NF、BCNF的定义和判断 –关系模式设计不好可能出现的问题 精选编辑pp...
语法 CREATE [OR REPLACE] TRIGGER TRIGGERNAME BEFORE|AFTER INSERT [OR UPDATE [OR DELETE]] ON TABLENAME [FOR EACH ROW] [WHEN EXPR] [DECLARE] BEGIN --PL/SQL块 END; 触发器 限制 1、代码不能超过32K长度,如果代码超过了32K,就要把代码写在存储过程中。在触发器中调用存储过程使用 CALL 存储过程(...
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•SELECT*FROMfacultyWHEREdept=‘MIS’ORrank=‘fullprofessor’;•SELECT*FROMfacultyWHEREdept=‘MIS’NOTrank=‘fullprofessor’;•SELECT*FROMclassWHEREroomLIKE‘b_s%’;•SELECT*FROMclassWHEREroomNOTLIKE‘bus%’;•SELECTproductid,productnameFROMinventoryWHEREonhandBETWEEN50and100;•SELECTcustomerid...
(select,insert,update,delete或者all)on数据库名.*to用户名@访问地址identifiedby“密码”;Flushprivileges;\\刷新系统权限表新建用户Grant操作权限(select,insert10删除用户Deletefromuserwhereuser=“test2”andhost=“localhost”;修改指定用户名密码:Updatemysql.usersetpassword=password(‘新密码‘)whereuser=“test2...