count(1), count(*), orderby1,2,3,4 difference

Count(1), count(*), order by 1,2,3,4 difference
the
1 make NULL data;
the

the
2 directly use the column name to COUNT to see the result
the

the
3 Use 1 2 3 4 5 * to COUNT to look at the results and find that they are all the same data and are equal to all functions.
www.2cto.com

the
4 ORDER BY 1 does use the first column to sort
the

the
5 ORDER BY 2 See if the result is correct
the

the
result:
the
count(1)=count(2)=count(3)=count(*);
the
count(provcode)count(areacode)count(statedate)count(*);
the
order by 1order by 2oreder by 3;
the
order by 1=order by provcode
the
Additional results:


the
the
the
Author ZengMuAnSha