sql選擇不同的行，其中項目是這樣的

Question

現在我正在使用一個asp頁面來循環查看一個大表，看看其中一行是否至少有一個項目在它是'1D％'，但是它需要大量的時間，它不僅需要'1D'，還需要至少30個其他兩個角色。是否有一個SQL查詢，可以使這個到一個表

感謝

OK的傢伙給你更多的什麼，我試圖做一個想法，我想這個查詢去得更快

sql2 = "SELECT code FROM products " 
set bs = MyConn.Execute(sql2) 
    do until bs.eof 
     if not bs.eof then 
      sql3 = "SELECT code FROM brand" 
      set ns = MyConn.Execute(sql3) 
       do until ns.eof 
        if not ns.eof then 
         sql = "SELECT TOP 1 sku, MID(sku, 1, 5) AS brand FROM catalog WHERE sku LIKE '"&bs.fields("code")&ns.fields("code")&"%' " 
         set rs = MyConn.Execute(sql) 
         do until rs.eof 
          if not rs.eof then 
           response.write(rs.fields("brand")&"<br>") 
          end if 
         rs.movenext 
         loop 
         set rs = Nothing 
        end if 
       ns.movenext 
       loop 
      set ns = nothing 
     end if 
    bs.movenext 
    loop 
set bs = Nothing 

輸出是這樣的 1DZOO 1FBAH 1FDRE 1FGRA 1FRIV 1FSCS 1FSEC 1FSUR 1CALI

Answer 1

要考慮的另一件事是將索引計算列添加到目錄表，這樣可以更容易地（和索引）查詢& - 加入。因爲SUBSTRING在本質上是確定的（計算列只能如果它們是確定性的索引），這些欄目將一樣快，一次索引（合理的），例如：

CREATE TABLE [dbo].[tbl_Example](
    [ID] [int] NULL, 
    [SKU] [varchar](50) NULL, 
    [Computed_Product] AS (substring([SKU],(1),(2))), 
    [Computed_Brand] AS (substring([SKU],(3),(2))) 
) ON [PRIMARY] 
GO 
SET ANSI_PADDING OFF 
GO 
CREATE NONCLUSTERED INDEX [IX_Computed_BrandCode] ON [dbo].[tbl_Example] 
(
    [Computed_Brand] ASC 
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] 
GO 
CREATE NONCLUSTERED INDEX [IX_ComputedProductCode] ON [dbo].[tbl_Example] 
(
    [Computed_Product] ASC 
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] 
GO 
INSERT [dbo].[tbl_Example] ([ID], [SKU]) VALUES (1, N'ASdasdasdL') 
INSERT [dbo].[tbl_Example] ([ID], [SKU]) VALUES (2, N'1231f2efwdsfas') 
INSERT [dbo].[tbl_Example] ([ID], [SKU]) VALUES (3, N'sdf23re2fwdf') 

Answer 2

你可以嘗試像

SELECT ... WHERE SUBSTRING(yourfield, 0, 2) IN ('1D', '2D', '3D', ...) 

Answer 3

你的意思是你是第一個裝載在記錄的所有數據，然後循環它在ASP來篩選呢？難怪它很慢！ SQL會像

SELECT 
    Col1, Col2 
FROM 
    Table1 
WHERE 
    SearchCol1 LIKE '1D%' 
    OR 
    SearchCol2 LIKE '1D%' 

這也不會很快，但會比現在快得多。