如何合並同一張表中的三個“選擇不同”

Question

對於搜索功能，我想返回三種類型的結果，因此我要查詢三次。 最好將JOIN或UNION查詢合並為一個，但是如何..

string sql1 = "SELECT DISTINCT area, CHARINDEX(@ss, area) FROM rgmaplocation WHERE area LIKE '%' + @ss + '%' ORDER BY CHARINDEX(@ss, area) ";
string sql2 = "SELECT DISTINCT compound, CHARINDEX(@ss, compound) FROM rgmaplocation WHERE compound LIKE '%' + @ss + '%' ORDER BY CHARINDEX(@ss, compound) ";
string sql3 = "SELECT DISTINCT streetname, CHARINDEX(@ss, streetname) FROM rgmaplocation WHERE streetname LIKE '%' + @ss + '%' ORDER BY CHARINDEX(@ss, streetname)";

Answer 1

像這樣通過charindex表達式來組合結果並進行排序。

;WITH C(Loc, Idx) AS
(
  SELECT DISTINCT area, CHARINDEX('g', area) 
  FROM rgmaplocation 
  WHERE area LIKE '%g%' 
  UNION ALL
  SELECT DISTINCT compound, CHARINDEX('g', compound) 
  FROM rgmaplocation 
  WHERE compound LIKE '%g%' 
  UNION ALL
  SELECT DISTINCT streetname, CHARINDEX('g', streetname) 
  FROM rgmaplocation 
  WHERE streetname LIKE '%g%' 
)
SELECT Loc, Idx
FROM C
ORDER BY Idx

Answer 2

如果您不介意將區域，化合物和街道名稱混在一起，則Mikael Eriksson的解決方案很好。 如果您想將它們分開，請繼續

WITH C(No,Loc, Idx) AS
(
  SELECT DISTINCT 1,area, CHARINDEX('g', area) 
  FROM rgmaplocation 
  WHERE area LIKE '%g%' 
  UNION 
  SELECT DISTINCT 2,compound, CHARINDEX('g', compound) 
  FROM rgmaplocation 
  WHERE compound LIKE '%g%' 
  UNION 
  SELECT DISTINCT 3,streetname, CHARINDEX('g', streetname) 
  FROM rgmaplocation 
  WHERE streetname LIKE '%g%' 
)
SELECT No,Loc, Idx
FROM C
ORDER BY No,Idx

Answer 3

如您所說，使用UNION應該看起來像：

string sqlAll = string.Format( "{0} UNION {1} UNION {2}", sql1, sql2, sql3 );