Oracle

Liquibase sql precondition is not checked

由 橙三吉。 提交于 2021-01-29 07:54:38
问题 I have multiple changelogs and one of the change log has the precondition on it to check if table exists, if so, skip running the migration. My change log file --liquibase formatted sql --preconditions onFail:MARK_RAN onError:MARK_RAN --precondition-sql-check expectedResult:0 select COUNT(*) C from dba_tables where UPPER(table_name) = 'PERSON' and upper(owner) = 'INT' --changeset nvoxland:3 create table int.person ( id int not null primary key, firstname varchar(80), lastname varchar(80) not

Streaming data from oracle db to browser with node.js

由 …衆ロ難τιáo~ 提交于 2021-01-29 07:37:58
问题 I am learning node.js and database. I am trying to stream heavy data about 7,700,000 rows and 96 columns from oracle to client. Later i use that data for virtual table. But in client it is showing only one row and then in node command error is displaying "Cannot set headers after they are sent to the client". How to stream data in client. Please help var oracledb = require('oracledb'); const cors = require('cors'); var express = require('express'); var app = express(); app.use(cors());

Streaming data from oracle db to browser with node.js

由 断了今生、忘了曾经 提交于 2021-01-29 07:35:45
问题 I am learning node.js and database. I am trying to stream heavy data about 7,700,000 rows and 96 columns from oracle to client. Later i use that data for virtual table. But in client it is showing only one row and then in node command error is displaying "Cannot set headers after they are sent to the client". How to stream data in client. Please help var oracledb = require('oracledb'); const cors = require('cors'); var express = require('express'); var app = express(); app.use(cors());

从B+树到LSM树，及LSM树在HBase中的应用

由 最后都变了- 提交于 2021-01-29 07:34:24
前言 在有代表性的关系型数据库如MySQL、SQL Server、Oracle中，数据存储与索引的基本结构就是我们耳熟能详的B树和B+树。而在一些主流的NoSQL数据库如HBase、Cassandra、LevelDB、RocksDB中，则是使用日志结构合并树（Log-structured Merge Tree，LSM Tree）来组织数据。本文先由B+树来引出对LSM树的介绍，然后说明HBase中是如何运用LSM树的。 回顾B+树 为什么在RDBMS中我们需要B+树（或者广义地说，索引）？一句话：减少寻道时间。在存储系统中广泛使用的HDD是磁性介质+机械旋转的，这就使得其顺序访问较快而随机访问较慢。使用B+树组织数据可以较好地利用HDD的这种特点，其本质是多路平衡查找树。下图是一棵高度为3的4路B+树示例。 与普通B树相比，B+树的非叶子节点只有索引，所有数据都位于叶子节点，并且叶子节点上的数据会形成有序链表。B+树的主要优点如下： 结构比较扁平，高度低（一般不超过4层），随机寻道次数少； 数据存储密度大，且都位于叶子节点，查询稳定，遍历方便； 叶子节点形成有序链表，范围查询转化为顺序读，效率高。相对而言B树必须通过中序遍历才能支持范围查询。 当然，B+树也不是十全十美的，它的主要缺点有两个： 如果写入的数据比较离散，那么寻找写入位置时，子节点有很大可能性不会在内存中

How to write mysql TIMESTAMPDIFF function in Oracle sql query

由 被刻印的时光 ゝ 提交于 2021-01-29 07:13:13
问题 I have query in Mysql which return minutes using TIMESTAMPDIFF in table. But now i have migrated my data to Oracle. So i want to use the same query to get the TIMESTAMPDIFF in a table in Oracle. Oracle also dont support NOW() function in mysql. The PROCESS_START_DATE column in query have data which contains date and time. I tried EXTRACT function in oraclebut did not work. Here is my query : select * from( select trunc(abs(to_date('27/01/2015 08:00:00','dd/mm/yyyy hh:mi:ss') - PMS.PROCESS

Dynamic Pivot Query using Sql Developer Oracle

由 喜夏-厌秋 提交于 2021-01-29 07:09:12
问题 Initial table students NAME School Class John Hs English Steve Hs Maths Matthew Hs Science Jim Hs History Output Needed: I need the query to auto pick up Name column data from initial table and change it to column headers in output and since the names will continuously change i cannot hard code the names using simple pivot query. I am new to pivot queries so I wanted to request if someone can help me out. Thank You. School John Steve Matthew Jim Hs English Maths Science History Here's what i

How can I create an index on the substring of a column?

由 丶灬走出姿态 提交于 2021-01-29 07:08:25
问题 I have a table containing key-value pairs which I would like to be ale to search efficiently on: SELECT * WHERE meta_key = "User ID" AND meta_value = "123userId"; However due to a legacy requirement the key and value NVARCHAR storage might be as large as 255 and 1000 characters respectively. Indexing on such large columns is not only costly but also outright restricted on some db types. I believe MySQL has a system to allow indexes by a LEFT -style substring as follows: CREATE INDEX ix

Retrieving and displaying data from oracle database

由 二次信任 提交于 2021-01-29 07:01:04
问题 First of all, I would like to THANK YOU for stopping by and spending your precious time for looking at my problem. I have 2 different tables within an Oracle Database. The first table holds metadata about the columns present in the other table. Think of the first (COL_TAB) table as a custom version of the ALL_TAB_COLS which comes by default with Oracle. COL_TAB ---------------------------------------------- | TABLE_NAME | COL_NAME | COL_DESC | ---------------------------------------------- |

How Can I Send Emails in PL/SQL (Oracle)?

由 橙三吉。 提交于 2021-01-29 06:44:06
问题 I have a procedure which count the number of rows in SMS_OUTBOX table and send emails if its row cont is over 1000. My procedure is given below: CREATE OR REPLACE PROCEDURE SEND_EMAIL_ABOUT_PENDING_SMS IS CHECK_SMS_COUNT NUMBER := 1000; CURRENT_SMS_COUNT NUMBER; BEGIN SELECT COUNT(1) INTO CURRENT_SMS_COUNT FROM SMS_SCHEMA.SMS_OUTBOX; IF CURRENT_SMS_COUNT >= CHECK_SMS_COUNT THEN UTL_MAIL.SEND( sender=>'<SENDER_EMAIL>', recipients=>'<RECIPIENT_EMAIL>', subject=>'Pending SMS', Message=>'Pending

SQL select table columns by matching Table 1 with 2 conditions in Table 2

由 拜拜、爱过 提交于 2021-01-29 06:42:07
问题 I would like to retrieve matches from two tables with below criteria: Fetch columns from Table_A and Table_B where A.some_name = B.j_name Table_A: **AB some_name G_NAME Status some_time** ------------------------------------------------------------ AAA Job1 xxxxxxxxx Ended OK 2020-06-29 10:37:52 AAA Job2 xxxxxxxxx Ended OK 2020-06-29 10:37:52 BBB AB-Job1 xxxxxxxxx Ended OK 2020-06-29 10:37:52 BBB AB-Job2 xxxxxxxxx Ended OK 2020-06-29 10:37:52 BBB AB-Job3 xxxxxxxxx Ended OK 2020-06-29 10:37:52
订阅 Oracle