可能重複:
Select * vs Specifying Column Names
Which is faster/best? SELECT * or SELECT column1, colum2, column3, etc.select * from tablename與select table1之間是否存在性能差異,並從tablename中選擇column1,column2?
有select * from tablename
和select column1, column2 from tablename
之間的性能差異?
當它是select * from
,數據庫翻出的所有字段/它們是大於2個的字段/列的列。第一個查詢會花費更多時間/資源嗎?
重複:http://stackoverflow.com/questions/1771795/select-vs-specifying-column-names/1771856 – 2009-12-08 09:28:44
和另一個:http://stackoverflow.com/questions/65512/which-is -faster-best-select-or-select-column1 -colum2-column3 -etype – 2009-12-08 09:29:29
當我用問題標題搜索前兩個結果討論相同的問題! – 2009-12-08 11:13:12