Data cleaning: Difference between revisions

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305 bytes added ,  22 September 2014
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# {{kbd | key = NULL}} value: {{kbd | key = SELECT * FROM table_name WHERE column_name IS NULL;}}  
# {{kbd | key = NULL}} value: {{kbd | key = SELECT * FROM table_name WHERE column_name IS NULL;}}  
# empty value: {{kbd | key = SELECT * FROM table_name WHERE LENGTH(TRIM( column_name )) = 0;}} {{exclaim}} SQL query with the condition {{kbd | key =SELECT * FROM table_name WHERE column_name IS NOT NULL}} includes empty value
# empty value: {{kbd | key = SELECT * FROM table_name WHERE LENGTH(TRIM( column_name )) = 0;}} {{exclaim}} SQL query with the condition {{kbd | key =SELECT * FROM table_name WHERE column_name IS NOT NULL}} includes empty value
#  Excel starting date: 1900/1/1, 1900/1/2 ... {{exclaim}} left blank intentionally
#  Excel starting date: 1900/1/0 (converted time formatted value from 0), 1900/1/1 (converted time formatted value from 1), 1900/1/2 ... {{exclaim}} Replace the year > 100 from this year with empty value at EXCEL: {{kbd | key =<nowiki>=IF(ISERR(YEAR(A2)), "", IF(YEAR(A2)<1914, "", A2))</nowiki>}} (this formula also handle empty value and non well-formatted column value ex: 0000-12-31 )


== check if field contains value ==
== check if field contains value ==

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