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Are COUNT and DISTINCT SQL-92 compliant?

I need to know whether the SQL functions COUNT and DISTINCT are SQL-92 compliant or not. That is, if I'm using...

an SQL-92 compliant database, may I expect them to be supported?

Yes, but watch out for the nuances.

COUNT(*) is the number of rows, without regard for the contents of any column.

COUNT([ALL] expression) is the number of non-null values of the expression -- usually a column name. ALL is the default, so it's not necessary. You see it used typically like COUNT(foobar) where foobar is a column -- the result is the number of non-null values.

COUNT(DISTINCT expression) is the number if distinct non-null values.

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This was last published in March 2002

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