**optdiag** column-level
statistics include:

Statistics giving the density and selectivity of columns. If an index includes more than one column,

**optdiag**prints the information described in Table 37-6 for each prefix subset of the index keys. If statistics are created using**update statistics**with a column name list, density statistics are stored for each prefix subset in the column list.A histogram, if the table contains one or more rows of data at the time the index is created or

**update statistics**is run. There is a histogram for the leading column for:Each index that currently exists (if there was at least one non-null value in the column when the index was created)

Any indexes that have been created and dropped (as long as

**delete statistics**has not been run)Any column list on which

**update statistics**has been run

There is also a histogram for:

Every column in an index, if the

**update index statistics**command was usedEvery column in the table, if the

**update all statistics**command was used

**optdiag** also prints a list of the columns
in the table for which there are no statistics. For example, here
is a list of the columns in the *authors* table
that do not have statistics:

No statistics for column(s): "address" (default values used) "au_fname" "phone" "state" "zipcode"