exist exists

1, determine whether the file exists, does not exist to create a file[Java]View Plaincopyprint? File file=new file ("c:\\users\\qping\\desktop\\javascript\\2.htm"); if (!file.exists ()) { try { File.createnewfile (); } catch

Use the shell script to monitor if the process has an instance that does not exist, starting with code dry:#!/bin/shPs-fe|grep processstring |grep-v grepIf [$?-ne 0]Thenecho "START process ..."Elseecho "Runing ..."Fi#####Processstring represents a

When the MySQL record does not exist, insert. When the record exists, there are basically three solutions to update the internet. First: Example 1: insert multiple records. Suppose There Is A client_id table with the primary key, you can use the

If (file. exists (xmlpath + "\" + xmlname) // checks whether the file is in the {// state. xmldocument xmldoc = new xmldocument (); xmldoc. load (xmlpath + "\" + xmlname); // The xmlnode root = xmldoc file exists. selectsinglenode ("History");

Let's take a look at the following example: Two system tables in Oracle. emp, dept. example: 1: not exists (not in) Not exists: This statement returns the result set that the select * from scott. dept d where e. deptno = d. deptno and d. deptno = 10

usingSystem;usingSystem.Collections.Generic;usingSystem.Linq;usingSystem.Text;usingSystem.Threading;usingSystem.Threading.Tasks;namespacesample3{classProgram {Static voidMain (string[] args) { varStudent1 =NewList(); Student1. ADD

How can I determine whether the data to be inserted already exists? count + 1 if it exists, and COUNT + 1 if it does not exist before insertion, insert data if it does not exist Reply to discussion (solution) Start

Use shell script to monitor whether a process exists without a startup instance, first on the code dry: #!/bin/shPs-fe|grep processstring |grep-v grepIf [$?-ne 0]Thenecho "START process ..."Elseecho "Runing ..."Fi#####Processstring represents a

MySQL insert when the record does not exist, update when the record exists, mysqlinsert   There are basically three solutions on the Internet. First: Example 1: insert multiple records Suppose there is a clients table with the primary key of

The IP address recorded in the text database. if the IP address already exists, it will not be added. if the IP address does not exist, it will be recorded in the text data. there will be a total of debugging errors. Document 1: & lt ;? Optional &