ddl

1. DDL （ Data Definition Language ） 数据库 定义语言 statements are used to define the database structure or schema. DDL是 SQL 语言的四大功能之一。 用于定义数据库的三级结构，包括外模式、概念模式、内模式及其相互之间的映像，定义数据的完整性、安全控制等约束 DDL不需要commit. CREATE ALTER DROP TRUNCATE COMMENT RENAME 2. DML （ Data Manipulation Language ） 数据操纵语言 statements are used for managing data within schema objects. 由DBMS提供，用于让用户或程序员使用，实现对数据库中数据的操作。 DML分成交互型DML和嵌入型DML两类。 依据语言的级别，DML又可分成过程性DML和非过程性DML两种。 需要commit. SELECT INSERT UPDATE DELETE MERGE CALL EXPLAIN PLAN LOCK TABLE 3. DCL （ Data Control Language ） 数据库控制语言 授权，角色控制等 GRANT 授权 REVOKE 取消授权 4. TCL （ Transaction

Closed. This question is off-topic. It is not currently accepting answers. Learn more . Want to improve this question? Update the question so it's on-topic for Stack Overflow. I know my question sounds a little bit like a shopping request, but I honestly believe that many people could find it useful. I've been looking for an automatic tool that converts Data Definition Language from MySQL dialect to Oracle dialect - the other way round would also be fine. I found “SQL Fairy” but I was unable to run it; probably because I'm not familiar with PERL. Is there any free tool for Windows that

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: Hello everybody I am learning DB2 and would like to know how to see a table's characteristics after I create one. Similar to the EXPLAIN TABLE command in MySQL. Thank you. 回答1: In addition to DESCRIBE TABLE, you can use the below DESCRIBE INDEXES FOR TABLE *tablename* SHOW DETAIL to get information about the table's indexes. The most comprehensive detail about a table on DB2 for Linux, UNIX, and Windows can be obtained from the db2look utility, which you can run from a remote client or directly on the DB2 server as a local user. The tool

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: How to generate the DDL for all tables in a database of MySQL at once. I know that the following query will output the DDL for a table. But I want DDL of all tables at once because I am having hundreds of tables in my database. show create table <database name>.<table name>; For example: show create table projectdb.customer_details; The above query will result in DDL of customer_details table. I am using MySQL with MySQL workbench on Windows OS. 回答1: You can do it using the mysqldump command line utility: mysqldump -d -u <username> -p

I have a user table with userid and username columns, and both are unique. Between userid and username , which would be better to use as a foreign key and why? My Boss wants to use string, is that ok? It looks like you have both a surrogate key ( int userId ) and a natural key ( char or varchar username ). Either column can be used as a Primary key for the table, and either way, you will still be able to enforce uniqueness of the other key. There are many existing discussions on the trade-offs between Natural and Surrogate Keys - you will need to decide on what works for you, and what the

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: If you're halfway through a transaction and perform a DDL statement, such as truncating a table, then the transaction commits. I was wondering whether this was always the case and by definition, or is there a setting hidden somewhere that would rollback the transaction instead of committing. Thanks. Edit to clarify... I'm not looking to rollback after a truncate. I just want to confirm that statements already carried out are absolutely always going to be committed before a DDL. Just want to make sure there isn't a system property somewhere

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: I am trying to execute an SQL command within dynamic SQL with bind variables: -- this procedure is a part of PL/SQL package Test_Pkg PROCEDURE Set_Nls_Calendar(calendar_ IN VARCHAR2) IS BEGIN EXECUTE IMMEDIATE 'ALTER SESSION SET NLS_CALENDAR = :cal' USING IN calendar_; END Set_Nls_Calendar; Then on the client side, I am trying to invoke the procedure: Test_Pkg.Set_Nls_Calendar('Thai Buddha'); But this get's me ORA-02248: invalid option for ALTER SESSION . And my question is: Why cannot I use bind variables in DDL/SCL statements in dynamic

DDL：数据定义语言，定义库、表结构用的 DML：数据操作语言，增、删、改、查 DCL：数据控制语言，权限、事务等控制语句 （一）DDL 1、操作数据库的语句 (1)查看当前DBMS中的所有数据库 show databases; (2)创建一个数据库 create database 数据库名; (3)删除一个数据库 drop database 数据库名; (4)使用，指定使用哪个数据库 use 数据库名; 有了这句后，下面的sql都是默认针对这个数据库的操作。 2、操作表格的语句 (1)查看某个库的所有表格 show tables; #必须前面有use 数据库名;的语句 否则报no database select的错误 show tables from 数据库名; (2)创建表格 基本版： create table 【数据库名.】表名称( 字段名1 数据类型, 字段名2 数据类型, 字段名2 数据类型, .... ); create table 【数据库名.】表名称(字段名1 数据类型,字段名2 数据类型,字段名2 数据类型,....); 注意：最后一个字段名的数据类型后面就不用加, 例如： create table employee( id int, name varchar(20), age int, salary double, gender char, birthday

Which are the differences between DBMS_UTILITY.EXEC_DDL_STATEMENT and EXECUTE IMMEDIATE ? Fundamentally they do the same thing, which is to provide a mechanism to execute DDL statements in PL/SQL, which isn't supported natively. If memory serves me well, the EXEC_DDL_STATEMENT was available in the Oracle 7 version of the DBMS_UTILITY package, whereas Native Dynamic SQL (EXECUTE IMMEDIATE) was only introduced in 8. There are a couple of differences. EXECUTE IMMEDIATE is mainly about executing dynamic SQL (as its NDS name indicates). the fact that we can use it for DDL is by-the-by. But the DBMS

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: I want to grant the CREATE ANY DIRECTORY permission to a user, with the following restriction: all directories created by this user must be inside of /foo/bar , and any attempt to create a directory outside of this should fail with a permission error. How may I do this on Oracle 11G or 12C? 回答1: That depends, if you want to restrict which OS directories Oracle can access from utl_file commands, you can set the utl_file_dir parameter. Unfortunately, this parameter is system wide, so you won't be able to grant/revoke for a specific user using