摘要： 1）. http://www.1keydata.com/sql/sql-case.html2）.http://blog.sqlauthority.com/ 3). http://sqlserverplanet.com/sql/alter-table-add-column/4).http://www.w3schools.com/sql/sql_alter.asp 阅读全文

摘要： http://blog.sqlauthority.com/SQLAuthority News – Monthly list of Puzzles and Solutions on SQLAuthority.comJune 28, 2011 by pinaldaveThis month has been very interesting month for SQLAuthority.com we had multiple and various puzzles which everybody participated and lots of interesting conversation w. 阅读全文

摘要： SQL SERVER – Difference Between Union vs. Union All – Optimal Performance ComparisonMarch 11, 2009 by pinaldaveMore than a year ago I had written article SQL SERVER – Union vs. Union All – Which is better for performance? I have got many request to update this article. It is not fair to update alre. 阅读全文

摘要： http://sqltutorials.blogspot.com/2007/06/sql-union-all.html--http://sqltutorials.phick1.com/ SQL UNION ALL SQL UNION ALL is combine the results of two queries together without filter out the same value(no distinct behavior). The difference between UNION ALL and UNION is UNION only selects distinct . 阅读全文