Data cleaning: Difference between revisions

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103 bytes added ,  18 December 2017
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** If the cell value is exactly {{kbd | key = NULL}} not {{kbd | key = #NULL!}}, You may use  {{kbd | key = <nowiki>COUNTIF(value, "NULL")</nowiki>}} or  {{kbd | key = <nowiki>EXACT(value, "NULL")</nowiki>}}
** If the cell value is exactly {{kbd | key = NULL}} not {{kbd | key = #NULL!}}, You may use  {{kbd | key = <nowiki>COUNTIF(value, "NULL")</nowiki>}} or  {{kbd | key = <nowiki>EXACT(value, "NULL")</nowiki>}}
* MySQL SQL syntax: {{kbd | key = SELECT * FROM table WHERE column IS NULL;}}<ref>[http://dev.mysql.com/doc/refman/5.0/en/working-with-null.html MySQL :: MySQL 5.0 Reference Manual :: 3.3.4.6 Working with NULL Values]</ref>  
* MySQL SQL syntax: {{kbd | key = SELECT * FROM table WHERE column IS NULL;}}<ref>[http://dev.mysql.com/doc/refman/5.0/en/working-with-null.html MySQL :: MySQL 5.0 Reference Manual :: 3.3.4.6 Working with NULL Values]</ref>  
* R: is.null(): [https://stat.ethz.ch/R-manual/R-devel/library/base/html/NULL.html R: The Null Object]


Find whether a variable is NOT NULL
Find whether a variable is NOT NULL

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