关于Sql语句执行效率的简单问题,请指教,谢谢!100分相送
efoxy 2006-11-09 08:24:11 1) select * from TableA where A_ID=1
2) select * from TableA where A_ID in (1)
3) select * from TableA where A_ID=1 OR A_ID=2
4) select * from TableA where A_ID in (1,2)
1)与2)比较哪个效率高些?
3)与4)比较哪个效率高些?
最好给些理论依据,谢谢!!