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(→Numeric: Check if the column value is integer) |
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== Check list == | |||
* Row count: The number of data entries is a fundamental item for data verification and is easy to observe and check. For instance, one can compare the number of entries displayed on a webpage to the number of entries after exporting to a CSV file. | |||
* Duplicate data | |||
== Check if field value was not fulfilled == | == Check if field value was not fulfilled == | ||
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</table> | </table> | ||
=== | === By datatype === | ||
==== VARCHAR and NOT allows NULL value ==== | |||
Using NULLIF() function<ref>[https://www.w3schools.com/sql/func_mysql_nullif.asp MySQL NULLIF() Function]</ref> | |||
SQL query: | |||
<pre> | |||
SELECT NULLIF(TRIM(`my_column`), "") | |||
</pre> | |||
Example result: | |||
<pre> | |||
SELECT NULLIF(null, ""); | |||
-- return NULL | |||
SELECT NULLIF("", ""); | |||
-- return NULL | |||
SELECT NULLIF(TRIM(" "), ""); | |||
-- return NULL | |||
SELECT NULLIF(TRIM("not empty string "), ""); | |||
-- return "not empty string" | |||
</pre> | |||
==== VARCHAR and allows NULL value ==== | ==== VARCHAR and allows NULL value ==== | ||
<table border="1" style="width: 100%"> | <table border="1" style="width: 100%"> | ||
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Validate the format of field value. Related page: [[Regular expression]] | Validate the format of field value. Related page: [[Regular expression]] | ||
=== Email contains @ symbol | === Verify the strings are in valid email format === | ||
Rule: Email contains @ symbol | |||
* EXCEL: {{kbd | key =<nowiki>=IF(ISERR(FIND("@", A2, 1)), FALSE, TRUE)</nowiki>}} only check the field if contains @ symbol or not | * EXCEL: {{kbd | key =<nowiki>=IF(ISERR(FIND("@", A2, 1)), FALSE, TRUE)</nowiki>}} only check the field if contains @ symbol or not | ||
** result: (1) normal condition: return TRUE; (2) exceptional condition: return '''FALSE''' if @ symbol was not found | ** result: (1) normal condition: return TRUE; (2) exceptional condition: return '''FALSE''' if @ symbol was not found | ||
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* PHP: [http://www.w3schools.com/php/filter_validate_email.asp PHP FILTER_VALIDATE_EMAIL Filter] | * PHP: [http://www.w3schools.com/php/filter_validate_email.asp PHP FILTER_VALIDATE_EMAIL Filter] | ||
** "Returns the filtered data, or '''FALSE''' if the filter fails." quoted from [http://php.net/manual/en/function.filter-var.php PHP.net] | ** "Returns the filtered data, or '''FALSE''' if the filter fails." quoted from [http://php.net/manual/en/function.filter-var.php PHP.net] | ||
=== Verify the strings are in valid url format === | |||
Rule: Begin with http or https | |||
* Google spreadsheet {{kbd | key =<nowiki>=REGEXMATCH(A1, "^http(s?)")</nowiki>}} | |||
=== Number precision in Excel === | === Number precision in Excel === | ||
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* If the data was imported from Excel, you should notice the 15 digit precision issue. | * If the data was imported from Excel, you should notice the 15 digit precision issue. | ||
=== | === Verify the column values are numeric === | ||
Possible values | |||
<pre> | |||
test data: | |||
3.141592654 | |||
1.36184E+14 | |||
123,456.789 | |||
20740199601 | |||
346183773390240 | |||
="5" | |||
</pre> | |||
==== Verify if value is number in MySQL ==== | |||
MySQL: | MySQL: | ||
* Find the records which the value of `my_column` is numeric values entirely {{code | code = SELECT * FROM `my_table` WHERE `my_column` REGEXP '^[0-9]+$'}}<ref>[http://stackoverflow.com/questions/14343767/mysql-regexp-with-and-numbers-only regex - Mysql REGEXP with . and numbers only - Stack Overflow]</ref> | |||
* Find the records which the value of `my_column` is '''NOT''' numeric values entirely {{code | code = SELECT * FROM `my_table` WHERE `my_column` NOT REGEXP '^[0-9]+$'}} | * Check if a value is integer e.g. 1234567 | ||
** Find the records which the value of `my_column` is numeric values entirely {{code | code = SELECT * FROM `my_table` WHERE `my_column` REGEXP '^[0-9]+$'}}<ref>[http://stackoverflow.com/questions/14343767/mysql-regexp-with-and-numbers-only regex - Mysql REGEXP with . and numbers only - Stack Overflow]</ref><ref>[https://stackoverflow.com/questions/75704/how-do-i-check-to-see-if-a-value-is-an-integer-in-mysql How do I check to see if a value is an integer in MySQL? - Stack Overflow]</ref> | |||
* Find the records which the value of `my_column` is not exactly 8 digits {{code | code = SELECT * FROM my_table WHERE LENGTH(my_column) != 8 OR my_column NOT REGEXP '^[0-9]{8}$'}} | |||
** The `LENGTH()` function checks if the string length is not 8 characters | |||
** The `REGEXP '^[0-9]{8}$'` pattern validates that the value contains exactly 8 digits from start (^) to end ($) | |||
** Using both conditions ensures catching values with correct length but non-numeric characters, as well as incorrect lengths | |||
* Check if a value is integer which may contains comma and dot symbols e.g. 1,234.567 or 3.414 | |||
** {{code | code = SELECT * FROM `my_table` WHERE `my_column` REGEXP '^[0-9,\.]+$'}}<ref>[https://community.denodo.com/answers/question/details?questionId=9060g000000XelhAAC&title=How+to+identify+if+values+in+a+column+is+numeric+%28+Function+similar+to+Isnumeric+is+SQL%29 How to identify if values in a column is numeric ( Function similar to Isnumeric is SQL)]</ref> | |||
* Check if a value is NOT integer | |||
** Find the records which the value of `my_column` is '''NOT''' numeric values entirely {{code | code = SELECT * FROM `my_table` WHERE `my_column` NOT REGEXP '^[0-9]+$'}} | |||
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* The {{kbd | key=tax_id}} column is 8 digits only. Find the well-formatted {{kbd | key=tax_id}} records by using {{code | code = SELECT * FROM `tax_id` WHERE `tax_id` REGEXP '^[0-9]{8}$'}} | * The {{kbd | key=tax_id}} column is 8 digits only. Find the well-formatted {{kbd | key=tax_id}} records by using {{code | code = SELECT * FROM `tax_id` WHERE `tax_id` REGEXP '^[0-9]{8}$'}} | ||
=== | ==== Verify if value is number in PHP ==== | ||
* [http://php.net/manual/en/function.is-numeric.php is_numeric] function | |||
* [https://www.php.net/manual/en/function.is-int.php is_int] function | |||
==== Verify if value is number in Excel or Google sheet ==== | |||
Excel & [https://www.google.com/sheets/about/ Google Sheets]: | Excel & [https://www.google.com/sheets/about/ Google Sheets]: | ||
* Using [http://www.techonthenet.com/excel/formulas/isnumber.php ISNUMBER Function]: {{code | code = <nowiki>=INT(ISNUMBER(A1))</nowiki>}} | * Using [http://www.techonthenet.com/excel/formulas/isnumber.php ISNUMBER Function]: {{code | code = <nowiki>=INT(ISNUMBER(A1))</nowiki>}} | ||
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** Return 1 if the cell value is (1) Numbers (2) Numbers that are stored as text e.g. {{code | code = <nowiki>="5"</nowiki>}} | ** Return 1 if the cell value is (1) Numbers (2) Numbers that are stored as text e.g. {{code | code = <nowiki>="5"</nowiki>}} | ||
** Return 0 if the cell value is (1) Text (2) Numbers in scientific (exponential) notation e.g. {{code | code = <nowiki>1.23E+16</nowiki>}} (3) Decimal numbers e.g. {{code | code = <nowiki>3.141592654</nowiki>}} (4) Negative numbers | ** Return 0 if the cell value is (1) Text (2) Numbers in scientific (exponential) notation e.g. {{code | code = <nowiki>1.23E+16</nowiki>}} (3) Decimal numbers e.g. {{code | code = <nowiki>3.141592654</nowiki>}} (4) Negative numbers | ||
=== Time data: Validate the data format === | === Time data: Validate the data format === | ||
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=== Time data: Data was generated in N years === | === Time data: Data was generated in N years === | ||
Define the abnormal values of the time data ([http://en.wikipedia.org/wiki/Time_series time series]) | Define the abnormal values of the time data ([http://en.wikipedia.org/wiki/Time_series time series]) | ||
* | * Verify the data were generated in N years. Possible abnormal values: {{code | code = 0001-01 00:00:00}} occurred in MySQL {{code | code = datetime}} type. e.g. | ||
* | |||
* | * Verify the data were not newer than today | ||
* Verify the year of data were not {{kbd | key=1900}} if the data were imported from Microsoft Excel file. Datevalue<ref>[https://support.microsoft.com/zh-tw/office/datevalue-%E5%87%BD%E6%95%B8-df8b07d4-7761-4a93-bc33-b7471bbff252 DATEVALUE 函數 - Office 支援]</ref> was started from the year {{kbd | key=1900}} e.g. | |||
** {{code | code = 1900/1/0}} (converted time formatted value from 0), | ** {{code | code = 1900/1/0}} (converted time formatted value from 0), | ||
** {{code | code = 1900/1/1}} (converted time formatted value from 1) | ** {{code | code = 1900/1/1}} (converted time formatted value from 1) | ||
* | * Verify the diversity of data values e.g. [https://en.wikipedia.org/wiki/Variance Variance] | ||
Find the normal values: | Find the normal values: | ||
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** {{code | code = SELECT * FROM `my_table` WHERE ( `my_time_column` >= CURDATE() - INTERVAL 10 YEAR ) AND ( `my_time_column` <= CURRENT_TIMESTAMP);}} | ** {{code | code = SELECT * FROM `my_table` WHERE ( `my_time_column` >= CURDATE() - INTERVAL 10 YEAR ) AND ( `my_time_column` <= CURRENT_TIMESTAMP);}} | ||
*** You need to check the {{code | code = SELECT CURRENT_TIMESTAMP);}} if correct or not before you delete the abnormal data (timezone issue) | *** You need to check the {{code | code = SELECT CURRENT_TIMESTAMP);}} if correct or not before you delete the abnormal data (timezone issue) | ||
Abnormal values | |||
* {{code | code = 1970-01-01 08:00:00}} (converted time formatted value from {{code | code =August 3, 2017}}) caused by the string contains special characters e.g. [https://en.wikipedia.org/wiki/Left-to-right_mark left-to-right mark (LRM) ] | |||
Check if the date valid | Check if the date valid | ||
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* [[Return symbol]] | * [[Return symbol]] | ||
* [http://www.fileformat.info/info/unicode/char/a0/index.htm Unicode Character 'NO-BREAK SPACE' (U+00A0)] | * [http://www.fileformat.info/info/unicode/char/a0/index.htm Unicode Character 'NO-BREAK SPACE' (U+00A0)] | ||
* [https://www.fileformat.info/info/unicode/char/200f/index.htm Unicode Character 'RIGHT-TO-LEFT MARK' (U+200F)] | |||
* [https://www.fileformat.info/info/unicode/char/200f/index.htm Unicode Character 'RIGHT-TO-LEFT MARK' (U+200F)]<ref>[https://stackoverflow.com/questions/1930009/how-to-strip-unicode-chars-left-to-right-mark-from-a-string-in-php regex - How to strip unicode chars (LEFT_TO_RIGHT_MARK) from a string in php - Stack Overflow]</ref> | |||
== | == File Validation == | ||
-- | === Verify the file format of downloaded file === | ||
* PDF file format: [https://stackoverflow.com/questions/16152583/tell-if-a-file-is-pdf-in-bash Tell if a file is PDF in bash - Stack Overflow] | |||
== Find and remove duplicates == | |||
[[Find and remove duplicates]] in Excel/BASH/MySQL/PHP | |||
MySQL | |||
== Counting == | == Counting == | ||
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# ASCII Horizontal Tab (TAB) {{kbd | key=<nowiki>\t</nowiki>}} | # ASCII Horizontal Tab (TAB) {{kbd | key=<nowiki>\t</nowiki>}} | ||
# ASCII Backspace {{kbd | key=<nowiki>\b</nowiki>}} | # ASCII Backspace {{kbd | key=<nowiki>\b</nowiki>}} | ||
# [ | # [[Remove non breaking space]] | ||
== Remove control character == | == Remove control character == | ||
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$result = preg_replace('/[\x00-\x1F]/', $replacement, $input); | $result = preg_replace('/[\x00-\x1F]/', $replacement, $input); | ||
</pre> | </pre> | ||
== Remove tracking parameter from link == | |||
[[Remove tracking parameter from link]] | |||
=== Fix garbled message text === | === Fix garbled message text === | ||
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== Tools == | == Tools == | ||
* [https://github.com/IvanMathy/Boop IvanMathy/Boop: A scriptable scratchpad for developers. In slow yet steady progress.] ([https://apps.apple.com/us/app/boop/id1518425043?mt=12 Boop on the Mac App Store]) " ... to paste some plain text and run some basic text operations on it. " | * {{Mac}} [https://github.com/IvanMathy/Boop IvanMathy/Boop: A scriptable scratchpad for developers. In slow yet steady progress.] ([https://apps.apple.com/us/app/boop/id1518425043?mt=12 Boop on the Mac App Store]) " ... to paste some plain text and run some basic text operations on it. " | ||
* [https://gchq.github.io/CyberChef/ CyberChef] (source code available on [https://github.com/gchq/CyberChef github]) The Cyber Swiss Army Knife - a web app for encryption, encoding, compression and data analysis | |||
== Further reading == | == Further reading == | ||
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* [https://medium.com/bryanyang0528/%E8%B3%87%E6%96%99%E5%93%81%E8%B3%AA%E5%88%9D%E6%8E%A2-data-quality-b765eb56a7c2?fbclid=IwAR3NBb2BtFm9O3FeY7JgQ5HLE5VG5nFe3m5Zx8zNW9XkvOUPlqV9hXmaoXI 資料品質初探(Data Quality) – 亂點技能的跨界人生 – Medium] {{access | date = 2018-01-13}} | * [https://medium.com/bryanyang0528/%E8%B3%87%E6%96%99%E5%93%81%E8%B3%AA%E5%88%9D%E6%8E%A2-data-quality-b765eb56a7c2?fbclid=IwAR3NBb2BtFm9O3FeY7JgQ5HLE5VG5nFe3m5Zx8zNW9XkvOUPlqV9hXmaoXI 資料品質初探(Data Quality) – 亂點技能的跨界人生 – Medium] {{access | date = 2018-01-13}} | ||
== | == References == | ||
<references/> | <references/> | ||
{{Template:Data factory flow}} | |||
[[Category:Spreadsheet]] [[Category:Excel]] | [[Category:Spreadsheet]] [[Category:Excel]] | ||