4/30/2023 0 Comments Psequel list databaseIf you did not understand the preceding paragraph then read the next section. The bottom line is this: if you try to start an application program and it complains that it cannot connect to the database, you should consult your site administrator or, if that is you, the documentation to make sure that your environment is properly set up. The environment variable PGPORT might also have to be set. For example, if the database server machine is a remote machine, you will need to set the PGHOST environment variable to the name of the database server machine. If your site administrator has not set things up in the default way, you might have some more work to do. Be sure to follow closely the section about setting up the appropriate environment variables. If you are installing PostgreSQL yourself, then refer to Chapter 17 for instructions on installation, and return to this guide when the installation is complete. PostgreSQL can be installed by any unprivileged user no superuser ( root) access is required. Doing so is not hard and it can be a good exercise. If you are not sure whether PostgreSQL is already available or whether you can use it for your experimentation then you can install it yourself. If that is the case, you should obtain information from the operating system documentation or your system administrator about how to access PostgreSQL. It is possible that PostgreSQL is already installed at your site, either because it was included in your operating system distribution or because the system administrator already installed it. # SELECT sum(price) FROM items avg = DB.Before you can use PostgreSQL you need to install it, of course. Or calculate a sum or average via sum and avg: sum = DB. Click on Connect to connect to the database. We’ll open PSequel and enter the name’s database, in our case: sampledb. This is mostly used to create databases, which we will create using the following command: create database sampledb Then, we connect to the database we just created using PSequel. # SELECT max(value) FROM history min = DB. This will open a ommand line that will allow you to enter commands. count # SELECT COUNT(*) FROM posts WHERE (category LIKE '%ruby%' ESCAPE '\')Īnd you can also query maximum/minimum values via max and min: max = DB. Summarizing Records ¶ ↑Ĭounting records is easy using count: posts. Please read the Security Guide for details on security issues that you should be aware of when using Sequel. Security ¶ ↑ĭesigning apps with security in mind is a best practice. See the Dataset Filtering file for more details. # Print out the number of records puts "Item count: # create_table :items do primary_key :id String :name Float :price end items = DB # Create a dataset # Populate the table items. Compare price, features, and reviews of the software side-by-side to make the best choice for your business. sqlite # memory database, requires sqlite3 DB. dbForge Studio using this comparison chart. Installation ¶ ↑ gem install sequel A Short Example ¶ ↑ require 'sequel' DB = Sequel. If you have any comments or suggestions please post to the Google group. To check out the source code: git clone git:///jeremyevans/sequel.git Contact ¶ ↑ Only use the the bug tracker to report bugs in Sequel, not to ask for help on using Sequel. Favorites from the Sequel Pro menu) then drag the favourites in the list. If you have questions about how to use Sequel, please ask on the sequel-talk Google Group. Im having trouble connecting to a MySQL 4 or MySQL 5 database on localhost. jeremyevans/sequel/discussions Alternate Discussion Forum (sequel-talk Google Group) jeremyevans/sequel/issues Discussion Forum (GitHub Discussions) jeremyevans/sequel Bug tracking (GitHub Issues) Sequel currently has adapters for ADO, Amalgalite, IBM_DB, JDBC, MySQL, Mysql2, ODBC, Oracle, PostgreSQL, SQLAnywhere, SQLite3, and TinyTDS. Sequel supports advanced database features such as prepared statements, bound variables, savepoints, two-phase commit, transaction isolation, primary/replica configurations, and database sharding. Sequel includes a comprehensive ORM layer for mapping records to Ruby objects and handling associated records. Sequel provides thread safety, connection pooling and a concise DSL for constructing SQL queries and table schemas. Sequel is a simple, flexible, and powerful SQL database access toolkit for Ruby. Snowflake: database metadata read performance was significantly improved Teradata: SQL query limit (TOP) support was added Many minor UI bugfixes New database driver: Apache Kyuubi Tweet. Sequel: The Database Toolkit for Ruby ¶ ↑
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |