ddl | 易学教程

To understand a sentence about the case in SQL/DDL -queries

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问题 This question is based on this answer. What does the following sentence mean? Finally, don't use mixed case identifiers. Do everything lowercase, so you don't have to quote them. Does it mean that I should change the commands such as CREATE TABLE, USER_ID and NOT NULL to lowercase? - It cannot because it would be against common naming conventions. 回答1: No, I think the gentleman referred to using all lowercase identifiers, e.g. table, column etc. names. This should have no impact on the

Define a VIEW in Oracle without using CREATE

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问题 I do not have sufficient privileges to use a CREATE statement, I can only SELECT . I have a script that has three distinct parts and calculations that need to run and each one references the same complicated WITH statement selection that redundantly clutters the code and is a pain to maintain in three separate locations. I have tried creating temp tables and views, but again, privileges do not support. Is there a way using either SQL or PL/SQL syntax to define my WITH statement ONCE without

What is the use of tablespace in the above query?

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问题 CREATE TABLE ts_pcode_tb_incase TABLESPACE USERS AS SELECT * FROM ts_pcode_tb; What is the use of tablespace in the above query? 回答1: A tablespace is a logical group of data files in a database. A database typically contains at least one tablespace, and usually two or more. Within the database, the tablespace plays a role similar to that of a folder on the hard drive of a computer. Some database programs, such as Oracle, automatically create a tablespace called SYSTEM that contains general

Hibernate DDL table Dynamic creation

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问题 I've a spring boot project, and I'm using hibernate to map my entities to DB, However now I have a new requirement: I need to be able to dynamically create tables in DB, without any mapping (so far). Does anyone know about some framework, to help me to deal with this: -I want to execute SQL or similar(ddl) to create my tables -I need to deal with connection management I've been told about spring-data, but I need some opinion about this. An example: Imagine I have a service available to client

Creating hive table with characters in the name

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问题 I am trying to create a table in hive with the following name "$example$table". It is not allowing me to create and is giving the following error: FAILED: Execution Error, return code 1 from org.apache.hadoop.hive.ql.exec.DDLTask. org.apache.hadoop.hive.ql.metadata.HiveException: [$ndo$dbproperty]: is not a valid table name Could anyone please help me out here? The requirement is to create tables name with characters like $,%,',' in the table name. 回答1: Currently, special characters are

Generate upgrade script to ALTER TABLE based on CREATE TABLE statement in Oracle [duplicate]

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问题 This question already has answers here : Automated Oracle Schema Migration Tool [closed] (5 answers) Closed 4 years ago . Is it possible in Oracle to generate a bunch of ALTER TABLE statements based on existing table in schema plus CREATE TABLE statement with newer definition of that table? Let's say I have a schema with some previous version of an application. I have an installation script for newest version of the application. The script creates all tables and sequences from scratch

Foreign keys, where they belong depending on relationships

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问题 I've worked with databases a fair bit ( MySQL, Oracle ) though typically only DML as the systems had been previously engineered. I'm working on a project as the sole developer, and am responsible for application development, and DBA; the latter of course proving more problematic. In any case - I need a refresh on foreign key constraints, and their logical placement in a model. Given the following: dbc_user .user_id INT, Primary Key, Auto Increment // arbitrary columns dbc_user_profile .user

create Cassandra database with Jenkins

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问题 Does anyone know how to run a DDL script to create a Cassandra database via Jenkins? I'm trying to connect to Cassandra through Jenkins in a testing environment in order to upload a test baseline dataset and run integration tests against it. 回答1: I created my own solution to solve a similar issue. Not just for testing, but for applying scripts in order as changes occur to the schema over time. It will work under Jenkins or wherever. There's a class to spin through the list of scripts in order

Alter multiple tables' columns length

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问题 So, we just found out that 254 tables in our Oracle DBMS have one column named "Foo" with the wrong length- Number(10) instead of Number(3) . That foo column is a part from the PK of the tables. Those tables have other tables with forigen keys to it. What I did is: backed-up the table with a temp table. Disabled the forigen keys to the table. Disabled the PK with the foo column. Nulled the foo column for all the rows. Restored all the above But now we found out it's not just couple of tables

oracle 死锁锁

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[zhuan]今天看群里在讨论数据库死锁的问题，也一起研究了下，查了些资料在这里总结下。所谓死锁：是指两个或两个以上的进程在执行过程中，因争夺资源而造成的一种互相等待的现象，若无外力作用，它们都将无法推进下去。此时称系统处于死锁状态或系统产生了死锁，这些永远在互相等待的进程称为死锁进程。由于资源占用是互斥的，当某个进程提出申请资源后，使得有关进程在无外力协助下，永远分配不到必需的资源而无法继续运行，这就产生了一种特殊现象死锁。关于数据库死锁的检查方法一、数据库死锁的现象程序在执行的过程中，点击确定或保存按钮，程序没有响应，也没有出现报错。二、死锁的原理当对于数据库某个表的某一列做更新或删除等操作，执行完毕后该条语句不提交，另一条对于这一列数据做更新操作的语句在执行的时候就会处于等待状态，此时的现象是这条语句一直在执行，但一直没有执行成功，也没有报错。三、死锁的定位方法通过检查数据库表，能够检查出是哪一条语句被死锁，产生死锁的机器是哪一台。 1）用dba用户执行以下语句 select username,lockwait,status,machine,program from v$session where sid in (select session_id from v$locked_object) 如果有输出的结果，则说明有死锁，且能看到死锁的机器是哪一台