SQL分类1) DDL(Data Definition Language)数据定义语言 用来定义数据库对象:数据库,表,列等。关键字:create, drop,alter 等 2) DML(Data Manipulation Language)数据操作语言 用来对数据库中表的数据进行增删改。关键字:insert, delete, update 等 3) DQL(Data Query Language)数据查询语言 用来查询数据库中表的...
[例3-1] 用SQL命令创建一个教学数据库Teach,数据文件的逻辑名称为Teach_Data,数据文件存放在D盘根目录下,文件名为TeachData.mdf,数据文件的初始存储空间大小为10MB,最大存储空间为50MB,存储空间自动增长量为5MB;日志文件的逻辑名称为Teach_Log,日志文件物理地存放在D盘根目录下,文件名为TeachData.ldf,初始存储空间...
A database is an organized collection of information. To manage databases, we need Data Base Management Systems (DBMS). A DBMS is a program that stores, retrieves, and modifies data in the databases on request. There have been different types of databases over the time: Hierarchical, network...
DBMS_OUTPUT.PUT_LINE ('循环内部,CONTINUE之前: x = ' || TO_CHAR(x)); x := x + 1; CONTINUE WHEN x > 3; DBMS_OUTPUT.PUT_LINE ('循环内部,CONTINUE之后: x = ' || TO_CHAR(x)); END LOOP; DBMS_OUTPUT.PUT_LINE (' 循环外部: x = ' || TO_CHAR(x)); END; / 执行结果如下:...
Additionally, DBMS_SQL enables you to parse any data manipulation language (DML) or data definition language (DDL) statement. Therefore, you can parse DDL statements directly using PL/SQL. For example, you might now choose to enter a DROP TABLE statement from within a stored procedure by ...
Every PL/SQL constant, variable, parameter, and function return value has a data type that determines its storage format and its valid values and operations.
User-defined types allow for the definition of data types that model the structure and behavior of the data in an application. Input CREATE TYPE t_line AS ( product_line VARCHAR2 ( 30 ) ,product_amount NUMBER ) ; ; Output CREATE TYPE sad_dml_product_pkg.t_line AS ( product_line VARCH...
SQL_DATABASE_NAME SQL_DBMS_NAME SQL_DBMS_VER 数据源信息 InfoType 参数的以下值返回有关数据源的信息,例如游标特征和事务功能: SQL_ACCESSIBLE_PROCEDURES SQL_ACCESSIBLE_TABLES SQL_BOOKMARK_PERSISTENCE SQL_CATALOG_TERM SQL_COLLATION_SEQ SQL_CONCAT_NULL_BEHAVIOR SQL_CURSOR_COMMIT_BEHAVIOR SQL_CURSOR_ROLL...
1. What is the difference between DBMS and RDBMS? The main difference between the DBMS(Database Management Systems) and RDBMS (Relational Database Management System) lies in how they handle the data. Feature DBMS RDBMS Data Storage Stores data as files or hierarchical structures Stores data in ...
1. What is the difference between DBMS and RDBMS? The main difference between the DBMS(Database Management Systems) and RDBMS (Relational Database Management System) lies in how they handle the data. Feature DBMS RDBMS Data Storage Stores data as files or hierarchical structures Stores data in ...