DatabaseLink`
DatabaseLink`
SQLConnectionOpenQ
SQLConnectionOpenQ[conn]
tests whether or not conn is a valid connection object.
更多信息和选项
- To use SQLConnectionOpenQ, you first need to load DatabaseLink using Needs["DatabaseLink`"].
- SQLConnectionOpenQ is strictly a client-side test and initiates no communication with the connection's target server, local or remote.
范例
打开所有单元关闭所有单元基本范例 (1)
If you find that the examples in this section do not work as shown, you may need to install or restore the example database with the "DatabaseLink`DatabaseExamples`" package, as described in Using the Example Databases.
Open a connection to a sample database:
Properties & Relations (1)
SQLConnectionOpenQ initiates no server communication, so a True result does not imply that queries may be issued on the connection. Use SQLConnectionUsableQ for this purpose:
Since SQLConnectionUsableQ performs server communication, it will generally take longer than SQLConnectionOpenQ to evaluate: