checksum

问题 I'm trying to compute a checksum or a hash for an entire table in SQL Server 2008. The problem I'm running into is that the table contains an XML column datatype, which cannot be used by checksum and has to be converted to nvarchar first. So I need to break it down into two problems: calculate a checksum for a row, schema is unknown before runtime. calculate the checksum for all of the rows to get the full table checksum. 回答1: You can use CHECKSUM_AGG. It only takes a single argument, so you

问题 I am currently writing a C program that builds a PNG image from a data file generated by another. The image is a palette type. Is the Adler-32 checksum calculated on the uncompressed data for... a) each compressed block within an IDAT data chunk? b) all compressed blocks within an IDAT data chunk? c) all compressed blocks spanning all IDAT data chunks? From the documents at http://www.w3.org/TR/PNG/, http://tools.ietf.org/html/rfc1950 and rfc1951 (at the same address as previuos) I am of the

问题 Looking to improved the security of my Android app to flag if the .apk has been extracted, modified, repacked and resigned. Here's article from Zdnet noting the issue link1. The concern is if the app is targeted by hackers they could add malicious code and upload to an alternate app store and dupe users in to downloading it. So I'm thinking code to verify a checksum of the apk or signing certificate? I appreciate the app code could be repacked and any security code removed, but it does

问题 According to the chart here: http://www.idautomation.com/barcode-faq/code-128/ This character: Ë equates to the value 103. Yet this code: string barcode = textBoxRawCode128.Text.Trim(); . . . int runningTotal = ConvertToASCIIInt(barCode[0]); . . . private int ConvertToASCIIInt(char valToConvertToASCII) { const int ASCII_ADJUSTMENT_VAL = 32; return valToConvertToASCII - ASCII_ADJUSTMENT_VAL; } ...when the value in the textbox and thus of barcode is "ËTry another string.", thus where barcode[0]

问题 I am writing a script to allow my host device to send data files to a slave device. The slave requires a checksum calculation to be made and added to the end of my requests prior to sending the file(s). My problem is that not only am I fairly new to programming, but I'm still trying to fully grasp bit manipulation. I'm currently in a Java class so the checksum function so portions of the functions do have a familiar format, but since I'm still scratching my head with bits and the bit library,

问题 I'm struggling to reverse engineer a section of data associated with a CRC-16 checksum. I know the polynom used to calculate the original checksums is 0x8408 but nothing else, I don't know initial value (if any), final XOR value (if any), if the input or the result is reflected... It seems like there is a known CRC-16 generator using thing polynom, CRC-16-CCITT but despite everything I've tried I just can't understand how the original checksum is being calculated. Here is the data I've got

问题 CONTEXT: we have big databases with loads of tables. Most of them (99%) are using innodb. we want to have a daily process that monitors which table has been modified. As they use innodb the value of Update_time from SHOW table STATUS from information_schema; is null. For that reason we want to create a daily procedure that will store the checksum (and other stuffs for that matters) of each table somewhere (preferably another table). On that, we will do different checks. PROBLEM: I'm trying to

问题 I have a field in a table with large content (text or binary data). If I want to know if another text is equals this one, I can use a checksum to compare the two texts. I can define this field as UNIQUE to avoid repeated content too. My doubt is if I create a checksum field, this comparison will speed up, so PostgreSQL already does this (without need programmer intervention) or I need do this manually? EDIT: What is better, create a checksum for a TEXT field, use a checksum for it or the two

问题 I have a solution in MS VS 2010 that compiles and builds properly after a rebuild all (1). However, after I make a change to a source file and begin debugging, VS recognizes the project is out of date and builds the project (2) successfully (as expected). The problem is that it seems VS begins debugging the project using obj/pdb/etc.. from (1) above instead of (2). If I break into the debugger and navigate to the module that changed in the file of interest, I'm told "the source file is

问题 I am looking to use java or groovy to get the md5 checksum of a complete directory. I have to copy directories for source to target, checksum source and target, and after delete source directories. I find this script for files, but how to do the same thing with directories ? import java.security.MessageDigest def generateMD5(final file) { MessageDigest digest = MessageDigest.getInstance("MD5") file.withInputStream(){ is -> byte[] buffer = new byte[8192] int read = 0 while( (read = is.read