error no database selected

I'm just learning to use PDO to manipulate the database, but, after connecting to the database, use Query () to execute the SELECT query statement, but always error: No database selected, code and error information as follows: setattribute

This is a database transaction error caused by the concurrency situation, and the background is introduced first.BackgroundSpringboot+springmvc+sqlserver+mybatisA controller has five or six interfaces, these interfaces are used in spring transaction

1, first put aside Mycat to deal with2. When querying a table, specify which database to be, and then query.①, if the MySQL Workbench is used first, use TableName, and then execute the action statement, or specify the database select * from

ArticleDirectory 1. Open the Enterprise Manager, expand the server, right-click the local server, and choose properties: 2. Select the regular window. The SQL Server proxy is automatically enabled: 3. Repeat Action 1. Open the SQL

BackgroundRecently, @ alizhengxiang (teacher Yang) posted a microblog on the top. Who knows, Shi has stirred up waves and friends from various database fields in China have posted a few new topics on this microblog, both radical debate and attack

This article mainly introduces the PHP database building table-configuration file-error log method, has a certain reference value, now share to everyone, the need for friends can refer to Main: organizing Frames Build a database and build

Access|select| Error |access|select Too long did not update this blog, not do not want to write, but usually contact with the ASP programming is almost an endorsement of the state, there is no creative coder work, there is no new ideas, there is no

Original post address: http://hym131690.blog.163.com/blog/static/642553162009212104926450/ I recently want to learn about network programming, and most socket programming environments are UNIX, which is inconvenient and cannot be compiled in windows.

selected collating sequence not supported by the operating system.   This issue occurs when you place a asp+access program on a foreign server .   is good at local testing. There is no problem, but after the transfer, the server prompts:

[[Email protected] ~] $! SQLSqlplus/As sysdba SQL * Plus: Release 11.2.0.1.0 production on Wed Aug 27 09:50:54 2014 Copyright (c) 1982,200 9, Oracle. All rights reserved. Connected:Oracle Database 11g Enterprise Edition Release 11.2.0.1.0-64bit