SQL and LINQ basics learn again

1. "Where clause is used inBefore grouping query resultsRemove rows that do not meet the where condition, that is, filter data before grouping,The condition cannot contain clustering functions., Use the where ConditionShow specific rows.

The having clause is used to filter groups that meet the conditions, that isFilter data After grouping,Conditions often contain aggregate functions., Using the having ConditionDisplay a specific group, You can also use multiple grouping standards for grouping ."

Http://www.cnblogs.com/Myhsg/archive/2008/08/05/1261386.html

2. Differences between takewhile and where.

If the where filter does not meet the conditions, the filter continues.

When takewhile Filtering does not meet the conditions, it will stop.

Skipwhile ignores the result set that meets the condition for the first time, but does not ignore the result set that meets the condition later.