现有2语句语句1:
Select * From (
Select * From tb_2009_01
Union All
Select * From tb_2009_02
Union All
......
Union All
Select * From tb_2009_09
Union All
Select * From tb_2009_10
)a Where a.SendTime>='2009-07-01 00:00:00' And a.SendTime<'2009-10-30 00:00:00'
语句2:
Select * From (
Select * From tb_2009_01 Where SendTime>='2009-07-01 00:00:00' And SendTime<'2009-10-30 00:00:00'
Union All
Select * From tb_2009_02 Where SendTime>='2009-07-01 00:00:00' And SendTime<'2009-10-30 00:00:00'
Union All
......
Union All
Select * From tb_2009_09 Where SendTime>='2009-07-01 00:00:00' And SendTime<'2009-10-30 00:00:00'
Union All
Select * From tb_2009_10 Where SendTime>='2009-07-01 00:00:00' And SendTime<'2009-10-30 00:00:00'
)a 不知道这2条语句哪条语句效率更高点,查询速度快点(差别就是条件放置的位置不同)
Select * From (
Select * From tb_2009_01
Union All
Select * From tb_2009_02
Union All
......
Union All
Select * From tb_2009_09
Union All
Select * From tb_2009_10
)a Where a.SendTime>='2009-07-01 00:00:00' And a.SendTime<'2009-10-30 00:00:00'
语句2:
Select * From (
Select * From tb_2009_01 Where SendTime>='2009-07-01 00:00:00' And SendTime<'2009-10-30 00:00:00'
Union All
Select * From tb_2009_02 Where SendTime>='2009-07-01 00:00:00' And SendTime<'2009-10-30 00:00:00'
Union All
......
Union All
Select * From tb_2009_09 Where SendTime>='2009-07-01 00:00:00' And SendTime<'2009-10-30 00:00:00'
Union All
Select * From tb_2009_10 Where SendTime>='2009-07-01 00:00:00' And SendTime<'2009-10-30 00:00:00'
)a 不知道这2条语句哪条语句效率更高点,查询速度快点(差别就是条件放置的位置不同)
解决方案 »
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