摘要：
http://blog.sqlauthority.com/2011/03/08/sql-server-difference-between-countdistinct-vs-countall/COUNT(DISTINCT)和COUNT(ALL)的区别：前者像select distinct 字段1,字段2 from table一样会去掉重复的，后者则是统计字段的所有数据条数，与Count(字段1)相同。COUNT(ALL)中的ALL实际上是缺省项，不需要指定。(注：本人还有点怀疑COUNT(ALL)与COUNT(字段1)是否有区别，待验证)。Here is the script:1 SELECT 阅读全文
摘要：
SQL Azure Performance – Query Optimization:http://www.sqlazureperformance.com/2010/sql-azure-performance-query-optimization/Simple Query tuning with STATISTICS IO and Execution plans:http://www.simple-talk.com/sql/performance/simple-query-tuning-with-statistics-io-and-execution-plans/显示图形执行计划 (SQL S 阅读全文