iif 函数　快　６倍　左右

２、Left$(string, 1)比Mid$(string, 1, 1)　快　４０％左右（Right$也一样）

３、判断空字符串 Len("") = 0比"" = ""　快 2.6倍左右

４、id = 9 \ 4 比id = Int(9 / 4) 快　４.5倍，注意 \  是整除

５、Do Until rs.EOF

k = k + 1

rs.MoveNext

Loop

--------------------------------------

kk = rs.RecordCount

For i = 1 To kk

k = k + 1

rs.MoveNext

Next

注：rs 的记录有　１２３４５６７条

Do 循环比 For 循环速度慢了　20%