We're only communicating with HTTP servers here as a convenient way of demonstrating the technique of waiting for data to arrive from a set of connected sockets. NOTE: As you'll see later, communicating with HTTP servers is better left to the Chilkat HTTP component/library because of many HTTP protocol issues such as redirects, GZIP responses, chunked responses, etc. It will call the SelectForReading method to wait until data arrives from any of the connected sockets. NumConnections.i = 5 This example will connect to 5 different web servers, send an HTTP request to each, and read the HTTP response form each. SaFilenames.i = CkStringArray:: ckCreate()ĬkStringArray:: ckAppend(saDomains, "CkStringArray:: ckAppend(saDomains, "CkStringArray:: ckAppend(saDomains, "CkStringArray:: ckAppend(saDomains, "CkStringArray:: ckAppend(saDomains, "CkStringArray:: ckAppend(saUrls, "")ĬkStringArray:: ckAppend(saFilenames, "chilkatsoft.out")ĬkStringArray:: ckAppend(saFilenames, "cknotes.out")ĬkStringArray:: ckAppend(saFilenames, "google.out")ĬkStringArray:: ckAppend(saFilenames, "example-code.out")ĬkStringArray:: ckAppend(saFilenames, "yahoo.out") Before we begin, create a few StringArray objects holding domain names, URLs, and output filenames to be used in this example. This will be the socket object that will contain other connected sockets. See Global Unlock Sample for sample code. This example requires the Chilkat API to have been previously unlocked. The SelectForReading method waits until one or more sockets in the set have incoming data ready and available to read. When you use the searched CASE expression within a SELECT statement, you can replace values in the result based on comparison values.Demonstrates how the Chilkat socket object can become a "socket set" that contains other connected socket objects, and this can be used to "select" on multiple sockets for reading. In other words, Oracle evaluates each Boolean condition to determine whether it is true, and never evaluates the next condition if the previous one is true. Like the simple CASE expression, Oracle also uses short-circuit evaluation for the searched CASE expression. If no Boolean expression is true, then the CASE expression returns the result expression in the ELSE clause if an ELSE clause exists otherwise, it returns a null value. It returns the result expression (r) of the first Boolean expression (e) that evaluates to true. The searched CASE expression evaluates the Boolean expression (e1, e2, …) in each WHEN clause in the order that the Boolean expressions appear. The following query uses the CASE expression to calculate the discount for each product category i.e., CPU 5%, video card 10%, and other product categories 8% We will use the products table in the sample database for the demonstration. As a result, Oracle never evaluates a comparison expression if a previous one equals the input expression (e). Oracle does not evaluate all comparison expressions before comparing any of them with the expression (e).
en) only before comparing one of them with the input expression (e). It means that Oracle evaluates each comparison expression (e1, e2. Oracle uses short-circuit evaluation for the simple CASE expression. If the input expression e does not match any comparison expression, the CASE expression returns the expression in the ELSE clause if the ELSE clause exists, otherwise, it returns a null value. If the input expression equals any comparison expression, the CASE expression returns the corresponding result expression (r). In this syntax, Oracle compares the input expression (e) to each comparison expression e1, e2, …, en.
#PUREBASIC SELECT CASE CODE#
END Code language: SQL (Structured Query Language) ( sql )
0 kommentar(er)
