我有下表：
Table1
Color Room type
Black Large
White Large
White Small
Black Medium
Black Small
我想运行一个查询：
请注意，我的查询比这更复杂，并且它有其他列和许多表，但我只想添加指定大房间大部分是白色还是黑色的列。
答案 0 :(得分：3)
适用于所有类型的房间：
SELECT RoomType
, Count( IIF(Color="White",1,NULL) ) AS CountWhite
, Count( IIF(Color="Black",1,NULL) ) AS CountBlack
, IIF( Count( IIF(Color="White",1,NULL) )
> Count( IIF(Color="Black",1,NULL) )
, "White"
, IIF( Count( IIF(Color="White",1,NULL) )
= Count( IIF(Color="Black",1,NULL) )
, NULL
, "Black"
)
)
AS Result
FROM Rooms
GROUP BY RoomType
仅适用于“大型”客房：
SELECT IIF( Count( IIF(Color="White",1,NULL) )
> Count( IIF(Color="Black",1,NULL) )
, "White"
, IIF( Count( IIF(Color="White",1,NULL) )
= Count( IIF(Color="Black",1,NULL) )
, NULL
, "Black"
)
)
AS Result
FROM Rooms
WHERE RoomType = "Large"
答案 1 :(得分：0)
由于你的问题尚不清楚，我们必须对你所追求的事情进行一些相当全面的猜测。如果你的表更像是：
Rooms
RoomID Color Room type
1 Black Large
2 White Large
3 White Small
4 Black Medium
5 Black Small
6 Black Large
7 White Large
8 White Small
9 White Large
10 White Large
如果您想知道这三种尺寸中是否有更多的黑色或白色房间，并且您指定了“有相同数量的黑白房间”（灰色？），以及MS Access可以使用这种语法，然后可能：
每种颜色的每种颜色的房间数：
SELECT [Room type] AS RoomType, Color, COUNT(*) AS RoomCount
FROM Rooms
GROUP BY RoomType, Color
自我加入此结果以将黑白计数转换为单个表格：
SELECT NVL(Black.RoomType, White.RoomType) AS RoomType,
NVL(WhiteCount, 0) AS WhiteCount,
NVL(BlackCount, 0) AS BlackCount
FROM (SELECT [Room type] AS RoomType, COUNT(*) AS WhiteCount
FROM Rooms
WHERE Color = 'White'
GROUP BY RoomType
) AS White
FULL OUTER JOIN
(SELECT [Room type] AS RoomType, COUNT(*) AS BlackCount
FROM Rooms
WHERE Color = 'Black'
GROUP BY RoomType
) AS Black
ON Black.RoomType = White.RoomType
（我不知道MS Access是否支持FULL OUTER JOIN。如果没有，你必须更加努力。同样，我没有检查它是否支持NVL - 也许它支持COALESCE。）
这将为您提供一系列行，每个房间类型一行，包含WhiteCount和BlackCount。
现在你只需要对其进行后期处理即可获得您所追求的信息 - 如果我的猜测是合理的。
编辑：必须在RoomType上使用NVL（）或等效内容并包含表别名;现在使用IBM Informix Dynamic Server 11.70.FC1在MacOS X 10.6.7上测试并生成正确答案：
Roomtype Whitecount Blackcount
Large 4 2
Small 2 1
Medium 0 1
如果MS Access不支持FULL OUTER JOIN，那么查询会非常混乱。它是否支持LEFT和RIGHT（OUTER）JOIN？让我们希望如此，因为那时你可以使用它（已更改为假设列名为Rooms.RoomType（名称中没有空格）：
SELECT NVL(White.RoomType, Black.RoomType) AS RoomType,
NVL(WhiteCount, 0) AS WhiteCount,
NVL(BlackCount, 0) AS BlackCount
FROM (SELECT RoomType AS RoomType, COUNT(*) AS WhiteCount
FROM Rooms
WHERE Color = 'White'
GROUP BY RoomType
) AS White
LEFT OUTER JOIN
(SELECT RoomType AS RoomType, COUNT(*) AS BlackCount
FROM Rooms
WHERE Color = 'Black'
GROUP BY RoomType
) AS Black
ON Black.RoomType = White.RoomType
UNION
SELECT NVL(White.RoomType, Black.RoomType) AS RoomType,
NVL(WhiteCount, 0) AS WhiteCount,
NVL(BlackCount, 0) AS BlackCount
FROM (SELECT RoomType AS RoomType, COUNT(*) AS WhiteCount
FROM Rooms
WHERE Color = 'White'
GROUP BY RoomType
) AS White
RIGHT OUTER JOIN
(SELECT RoomType AS RoomType, COUNT(*) AS BlackCount
FROM Rooms
WHERE Color = 'Black'
GROUP BY RoomType
) AS Black
ON Black.RoomType = White.RoomType;
此配方依赖于UNION删除重复的行。给定测试数据，它产生相同的结果。您可以通过在UNION的前半部分（而不是NVL表达式）的主选择列表中使用White.RoomType并在下半部分使用Black.RoomType来压缩它。
如果MS Access不支持任何外部联接，那么（a）是时候升级到真正的DBMS了，（b）让我知道，我们将制定出长期的3路UNION方式同样的工作。
答案 2 :(得分：0)
由于这是Access（ACE，Jet，等等），我们可能需要通过VIEW s（保存的查询对象，querydef等）使用中间结果集：
CREATE VIEW Table1ColorTallies
(
Color, tally
)
AS
SELECT Color, COUNT(*) AS tally
FROM Table1
GROUP
BY Color;
CREATE VIEW Table1ColorsWithMaxTallies
(
Color
)
AS
SELECT T1.Color
FROM Table1ColorTallies AS T1
WHERE T1.tally = (
SELECT MAX(T2.tally)
FROM Table1ColorTallies AS T2
);
使用VIEW来获得所需的结果：
SELECT Color
FROM Table1ColorsWithMaxTallies
WHERE 1 = (
SELECT COUNT(*)
FROM Table1ColorsWithMaxTallies AS T2
);
注意上面的CREATE VIEW SQL DDL必须在ANSI-92 Query Mode中单独执行 。或者，使用Access UI（DAO，无论如何）以通常的方式将它们创建为已保存的查询对象（querydef，无论如何）。
这里有一些VBA在你的临时文件夹中创建一个名为DropMe.mdb的新数据库，用示例数据创建Table1，然后创建我的建议VIEW并在一个显示我的建议查询的结果消息框。使用ADO但不需要引用（使用后期绑定）。只需粘贴任何VBA标准代码模块（例如使用Excel）并运行即可。我认为它可以很好地扩展到超过1种颜色;）
Sub BlackAndWhite()
On Error Resume Next
Kill Environ$("temp") & "\DropMe.mdb"
On Error GoTo 0
Dim cat
Set cat = CreateObject("ADOX.Catalog")
With cat
.Create _
"Provider=Microsoft.Jet.OLEDB.4.0;" & _
"Data Source=" & _
Environ$("temp") & "\DropMe.mdb"
With .ActiveConnection
Dim Sql As String
Sql = _
"CREATE TABLE Table1" & vbCr & "(" & vbCr & " Color VARCHAR(100)" & _
" NOT NULL, " & vbCr & " Room_type NVARCHAR(100) NOT" & _
" NULL, " & vbCr & " UNIQUE (Color, Room_type)" & vbCr & ");"
.Execute Sql
Sql = _
"CREATE VIEW Table1ColorTallies" & vbCr & "(" & vbCr & " Color," & _
" tally" & vbCr & ")" & vbCr & "AS " & vbCr & "SELECT Color, COUNT(*) AS tally" & vbCr & "" & _
" FROM Table1" & vbCr & " GROUP " & vbCr & " BY Color;"
.Execute Sql
Sql = _
"CREATE VIEW Table1ColorsWithMaxTallies" & vbCr & "(" & vbCr & "" & _
" Color" & vbCr & ")" & vbCr & "AS " & vbCr & "SELECT T1.Color" & vbCr & " FROM Table1ColorTallies" & _
" AS T1" & vbCr & " WHERE T1.tally = (" & vbCr & " " & _
" SELECT MAX(T2.tally)" & vbCr & " " & _
" FROM Table1ColorTallies AS T2" & vbCr & "" & _
" );"
.Execute Sql
Sql = _
"INSERT INTO Table1 (Color, Room_type) VALUES" & _
" ('Black', 'Large');"
.Execute Sql
Sql = _
"INSERT INTO Table1 (Color, Room_type) VALUES" & _
" ('White', 'Large');"
.Execute Sql
Sql = _
"INSERT INTO Table1 (Color, Room_type) VALUES" & _
" ('White', 'Small');"
.Execute Sql
Sql = _
"INSERT INTO Table1 (Color, Room_type) VALUES" & _
" ('White', 'Med');"
.Execute Sql
Sql = _
"INSERT INTO Table1 (Color, Room_type) VALUES" & _
" ('Black', 'Small');"
.Execute Sql
Sql = _
"SELECT Color" & vbCr & " FROM Table1ColorsWithMaxTallies" & vbCr & "" & _
" WHERE 1 = (" & vbCr & " SELECT COUNT(*)" & vbCr & "" & _
" FROM Table1ColorsWithMaxTallies" & _
" AS T2" & vbCr & " );"
Dim rs
Set rs = .Execute(Sql)
MsgBox rs.GetString
End With
Set .ActiveConnection = Nothing
End With
End Sub
答案 3 :(得分：0)
我认为以下内容可以实现您所描述的内容：
SELECT RoomType,
IIF(BlackCount>WhiteCount, "Black", IIF(BlackCount<WhiteCount, "White", "Unidentified")) AS PrevailingColor
FROM
(SELECT RoomType, SUM(IIF(Color="Black",1,0)) AS BlackCount, SUM(IIF(Color="White",1,0)) AS WhiteCount
FROM Table1
GROUP BY RoomType)
;
答案 4 :(得分：0)
您可以尝试以下实现：
//asume g is from input
int g = 4;
for(int x = 1; x <=g;x++){
int d = x;
for(int y = 1;y<=g;y++){
System.out.print(d+" ");
d = g*x-y;
}
System. out. println();
}
output:
1 3 2 1
2 7 6 5
3 11 10 9
4 15 14 13
答案 5 :(得分：-1)
从MS Access中的以下查询开始。在我的示例中，我使用名称qryRoomColorCounts：
保存了它SELECT
tblRooms.RoomType, tblRooms.Color, Count(*) AS ColorCount
FROM tblRooms
GROUP BY tblRooms.RoomType, tblRooms.Color
然后，您可以使用此SQL获取结果：
SELECT
tblRooms.RoomType,
(SELECT TOP 1 qryRoomColorCounts.Color FROM qryRoomColorCounts WHERE
qryRoomColorCounts.RoomType=tblRooms.RoomType
ORDER BY qryRoomColorCounts.ColorCount DESC) AS MostUsedColor
FROM tblRooms
GROUP BY tblRooms.RoomType
我无法得到你的建议，你能调试吗：不需要引用（使用后期绑定），只需粘贴到任何VBA标准代码模块（例如使用Excel）并运行：
Sub NotSoBlackAndWhite()
On Error Resume Next
Kill Environ$("temp") & "\DropMe2.mdb"
On Error GoTo 0
Dim cat
Set cat = CreateObject("ADOX.Catalog")
With cat
.Create _
"Provider=Microsoft.Jet.OLEDB.4.0;" & _
"Data Source=" & _
Environ$("temp") & "\DropMe2.mdb"
With .ActiveConnection
Dim Sql As String
Sql = _
"CREATE TABLE tblRooms" & vbCr & "(" & vbCr & " Color VARCHAR(100)" & _
" NOT NULL, " & vbCr & " RoomType NVARCHAR(100) NOT" & _
" NULL, " & vbCr & " UNIQUE (Color, RoomType)" & vbCr & ");"
.Execute Sql
Sql = _
"CREATE VIEW qryRoomColorCounts AS " & vbCr & "SELECT" & _
" " & vbCr & "tblRooms.RoomType, tblRooms.Color, Count(*)" & _
" AS ColorCount " & vbCr & "FROM tblRooms " & vbCr & "GROUP BY" & _
" tblRooms.RoomType, tblRooms.Color"
.Execute Sql
Sql = _
"INSERT INTO tblRooms (Color, RoomType) VALUES" & _
" ('Black', 'Large');"
.Execute Sql
Sql = _
"INSERT INTO tblRooms (Color, RoomType) VALUES" & _
" ('White', 'Large');"
.Execute Sql
Sql = _
"INSERT INTO tblRooms (Color, RoomType) VALUES" & _
" ('White', 'Small');"
.Execute Sql
Sql = _
"INSERT INTO tblRooms (Color, RoomType) VALUES" & _
" ('White', 'Med');"
.Execute Sql
Sql = _
"INSERT INTO tblRooms (Color, RoomType) VALUES" & _
" ('Black', 'Small');"
.Execute Sql
Sql = _
"SELECT " & vbCr & "tblRooms.RoomType, " & vbCr & "(SELECT TOP" & _
" 1 qryRoomColorCounts.Color FROM qryRoomColorCounts" & _
" WHERE" & vbCr & " qryRoomColorCounts.RoomType=tblRooms.RoomType" & _
" " & vbCr & " ORDER BY qryRoomColorCounts.ColorCount" & _
" DESC) AS MostUsedColor " & vbCr & "FROM tblRooms " & vbCr & "GROUP" & _
" BY tblRooms.RoomType"
Dim rs
Set rs = .Execute(Sql) ' <--- ERROR HERE '
MsgBox rs.GetString
End With
Set .ActiveConnection = Nothing
End With
End Sub