More PHP

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More PHP
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Strings

• Assign str1 the value how are you guys?
• str1 how are you guys
• Assign str2 the value were great
• str2 we\re great
• Assign str3 the value of str1 and then str2
• str3 str1 . str2
• str3 str1 . . str2

NO! there should be a space between these two
lines
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PHP Strings MYSQL

• MYSQL takes input like
• SELECT id, user from usertable where user
  gillw3
• SELECT id, user from usertable where id 7
• To write SQL in PHP
• Assume we have stored the user id and name in id
  and user
• sql SELECT id, user from usertable where user
  \ . user . \
• sql SELECT id, user from usertable where id
  . id

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Strings Functions

• Orderly and Readable
• cust mysql_real_escape_string(_GETexclude)
  
• sql SELECT Customer,OrderDate,SUM(OrderPrice)
  
• sql . FROM Orders
• sql . where Customer ! \. cust . \
• sql . GROUP BY Customer,OrderDate
• //echo sql
• result mysql_query(sql)

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Strings Functions

• Terrible
• result mysql_query(SELECT Customer,OrderDate,S
  UM(OrderPrice) FROM Orders where Customer ! \.
  mysql_real_escape_string(_GETexclude). \
  GROUP BY Customer,OrderDate)

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Other Times to Escape

• Using PHP to write Javascript
• Using PHP to write HTML

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PHP to write JS

• Writing a JS array
• var myarray new Array(val1, val2, val3)
• Using PHP to create the above array
• jsoutput var myarray new Array(\
• for(i 1 i lt 3 i)
• jsoutput . \val . i . \,
• jsoutput . )

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PHP to write HTML

• Creating a link, with the url stored in URL and
  the link text stored in text
• Desired HTML
• lta hrefhttp//www.rpi.edugt RPI lt/agt
• With PHP
• echo lta href\ . URL . \gt . text .
  lt/agt

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Error Checking

• Turn on error reporting in php (even if it is off
  in PHP.INI)
• error_reporting(E_ALL)
• Check for results frequently

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Resources

• Check the documentation, many functions return
  resources.
• Resources cannot be directly manipulated

Function returns a resource
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Page Based Applications

• listproducts.php
• displayproduct.php

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ListProducts.php

• Connects to db
• Selects all products from DB
• Loops over results
• Prints out link to product
• lta hrefdisplayproduct.php?pid.id.gtptitle.
  lt/agt
• Closes DB connection

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DisplayProduct.php

• Connects to DB
• Takes a product ID from the querystring
• If no ID/an invalid ID is given, redirects user
  to listproducts.php
• Selects product from DB
• Displays product data
• Closes DB connection