如何访问 T-SQL 中列表中的值？
我有一个 SQL 语句，用于循环并计算某个值在 Table_1 的特定列中出现的次数。然后，它将所需的值插入到 Table_2 上的列中，或者如果该行不存在，则会添加一个新行并添加必要的数据。
准确地说，我创建了列表或表格，
DECLARE @MyList TABLE (Value NVARCHAR(50))
INSERT INTO @MyList VALUES ('Data1')
INSERT INTO @MyList VALUES ('Data2')
INSERT INTO @MyList VALUES ('Data3')
INSERT INTO @MyList VALUES ('Data4')
INSERT INTO @MyList VALUES ('Data5')
INSERT INTO @MyList VALUES ('Data6')
INSERT INTO @MyList VALUES ('Data7')
INSERT INTO @MyList VALUES ('Data8')
该语句工作正常，但我已经对所有内容进行了硬编码，并且我想添加一些要插入的动态数据，因此我创建了一个值列表(字符串)。现在我无法按照我想象的方式访问这些值。
这是整个声明，
DECLARE @cnt INT = 1;
DECLARE @MyList TABLE (Value NVARCHAR(50))
INSERT INTO @MyList VALUES ('Data1')
INSERT INTO @MyList VALUES ('Data2')
INSERT INTO @MyList VALUES ('Data3')
INSERT INTO @MyList VALUES ('Data4')
INSERT INTO @MyList VALUES ('Data5')
INSERT INTO @MyList VALUES ('Data6')
INSERT INTO @MyList VALUES ('Data7')
INSERT INTO @MyList VALUES ('Data8')
WHILE @cnt < 9
BEGIN
IF EXISTS (SELECT * FROM Staff_Manager.dbo.Staff_Count_TBL WHERE Staff_No = 3201 AND Year_D = 2016 AND Month_D = 6 AND Column_Index = @cnt)
BEGIN
UPDATE Staff_Manager.dbo.Staff_Count_TBL
SET Column_Value = (
SELECT COUNT(*)
FROM Staff_Manager.dbo.Staff_Time_TBL
WHERE Staff_No = 3201 AND Date_Data BETWEEN '2016/6/1' AND '2016/7/1' AND Info_Data = 'Data_1'
GROUP BY Staff_No, Info_Data),
Column_Value2 = 'Data1'
WHERE Staff_No = 3201 AND Year_D = 2016 AND Month_D = 6 AND Column_Index = @cnt
END
ELSE
BEGIN
INSERT INTO Staff_Manager.dbo.Staff_Count_TBL
(Staff_No, Year_D, Month_D, Column_Index, Column_Value, Column_Value2)
SELECT 3201, 2016, 6, @cnt, COUNT(*), 'Data1'
FROM Staff_Manager.dbo.Staff_Time_TBL
WHERE Staff_No = 3201 AND Date_Data BETWEEN '2016/6/1' AND '2016/7/1' AND Info_Data = 'Data1'
GROUP BY Staff_No, Info_Data
END
SET @cnt = @cnt + 1
END
我想要实现的是循环遍历一个包含 8 个项目的列表，并将这些值输入到相应的列中。
例如，
在这一行我硬编码了Data1，
WHERE Staff_No = 3201 AND Date_Data
BETWEEN '2016/6/1' AND '2016/7/1' AND Info_Data = 'Data1'
我想做的是这个，
WHERE Staff_No = 3201 AND Date_Data
BETWEEN '2016/6/1' AND '2016/7/1' AND Info_Data = @MyList[@cnt]
还有这个，
SELECT 3201, 2016, 6, @cnt, COUNT(*), @MyList[@cnt]
FROM Staff_Manager.dbo.Staff_Time_TBL
WHERE Staff_No = 3201 AND Date_Data
BETWEEN '2016/6/1' AND '2016/7/1' AND Info_Data = @MyList[@cnt]
但这不起作用。经过更多研究后，我发现 T-SQL 实际上并没有创建一个列表，而是一个临时表，可以这么说，您需要从那里获取值。不幸的是我似乎无法做任何事情。
我有一个 UPDATE 和一个 INSERT 语句，我需要从列表中添加值。
编辑:最后一刻代码调整，
DECLARE @cnt INT = 1;
DECLARE @MyList TABLE (Value NVARCHAR(50))
INSERT INTO @MyList VALUES ('Data1')
INSERT INTO @MyList VALUES ('Data2')
INSERT INTO @MyList VALUES ('Data3')
INSERT INTO @MyList VALUES ('Data4')
INSERT INTO @MyList VALUES ('Data5')
INSERT INTO @MyList VALUES ('Data6')
INSERT INTO @MyList VALUES ('Data7')
INSERT INTO @MyList VALUES ('Data8')
INSERT INTO @MyList VALUES ('Data9')
INSERT INTO @MyList VALUES ('Data10')
INSERT INTO @MyList VALUES ('Data11')
INSERT INTO @MyList VALUES ('Data12')
INSERT INTO @MyList VALUES ('Data13')
INSERT INTO @MyList VALUES ('Data14')
INSERT INTO @MyList VALUES ('Data15')
INSERT INTO @MyList VALUES ('Data16')
INSERT INTO @MyList VALUES ('Data17')
INSERT INTO @MyList VALUES ('Data18')
INSERT INTO @MyList VALUES ('Data19')
INSERT INTO @MyList VALUES ('Data20')
INSERT INTO @MyList VALUES ('Data21')
INSERT INTO @MyList VALUES ('Data22')
INSERT INTO @MyList VALUES ('Data23')
INSERT INTO @MyList VALUES ('Data24')
INSERT INTO @MyList VALUES ('Data25')
INSERT INTO @MyList VALUES ('Data26')
INSERT INTO @MyList VALUES ('Data27')
INSERT INTO @MyList VALUES ('Data28')
INSERT INTO @MyList VALUES ('Data29')
INSERT INTO @MyList VALUES ('Data30')
DECLARE @COUNTER INT = 0;
DECLARE @MAX INT = (SELECT COUNT(*) FROM @MyList)
DECLARE @VALUE VARCHAR(50);
WHILE @cnt <= @MAX
BEGIN
SET @VALUE = (SELECT Value FROM @MyList
ORDER BY 1 OFFSET @COUNTER
ROWS FETCH NEXT 1 ROWS ONLY);
PRINT @cnt
PRINT @VALUE
PRINT @COUNTER
IF EXISTS (SELECT * FROM Staff_Manager.dbo.Staff_Count_TBL WHERE Staff_No = 3005 AND Year_D = 2016 AND Month_D = 6 AND Column_Index = @cnt)
BEGIN
UPDATE Staff_Manager.dbo.Staff_Count_TBL
SET Column_Value = (
SELECT COUNT(*)
FROM Staff_Manager.dbo.Staff_Time_TBL
WHERE Staff_No = 3005 AND Date_Data BETWEEN '2016/6/1' AND '2016/7/1' AND Info_Data = @value
GROUP BY Staff_No, Info_Data),
Column_Value2 = @value
WHERE Staff_No = 3005 AND Year_D = 2016 AND Month_D = 6 AND Column_Index = @cnt
END
ELSE
BEGIN
INSERT INTO Staff_Manager.dbo.Staff_Count_TBL
(Staff_No, Year_D, Month_D, Column_Index, Column_Value, Column_Value2)
SELECT 3005, 2016, 6, @cnt, COUNT(*), @value
FROM Staff_Manager.dbo.Staff_Time_TBL
WHERE Staff_No = 3005 AND Date_Data BETWEEN '2016/6/1' AND '2016/7/1' AND Info_Data = @value
GROUP BY Staff_No, Info_Data
END
SET @cnt = @cnt + 1
SET @COUNTER = @COUNTER + 1
END
最佳答案
您创建的不是列表，而是表变量。那么如何迭代表。下面是一个简单的例子，我想如果你理解了它就可以继续:
(注意:游标在性能和大型表方面效率不高)
DECLARE @MyList TABLE (Value NVARCHAR(50))
INSERT INTO @MyList VALUES ('Data1')
INSERT INTO @MyList VALUES ('Data2')
INSERT INTO @MyList VALUES ('Data3')
INSERT INTO @MyList VALUES ('Data4')
INSERT INTO @MyList VALUES ('Data5')
INSERT INTO @MyList VALUES ('Data6')
INSERT INTO @MyList VALUES ('Data7')
INSERT INTO @MyList VALUES ('Data8')
DECLARE @value VARCHAR(50)
DECLARE db_cursor CURSOR FOR
SELECT Value FROM @MyList
OPEN db_cursor
FETCH NEXT FROM db_cursor INTO @value
WHILE @@FETCH_STATUS = 0
BEGIN
PRINT @value
-- PUT YOUR LOGIC HERE
-- MAKE USE OR VARIABLE @value wich is Data1, Data2, etc...
FETCH NEXT FROM db_cursor INTO @value
END
CLOSE db_cursor
DEALLOCATE db_cursor
打印:
Data1
Data2
Data3
Data4
Data5
Data6
Data7
Data8
所以你有内部@value变量Data，Data2 ..等。我认为这可以解决您的问题。
替代方法是使用 WHILE 循环 + OFFSET + FETCH NEXT :
DECLARE @MyList TABLE (Value NVARCHAR(50))
INSERT INTO @MyList VALUES ('Data1')
INSERT INTO @MyList VALUES ('Data2')
INSERT INTO @MyList VALUES ('Data3')
INSERT INTO @MyList VALUES ('Data4')
INSERT INTO @MyList VALUES ('Data5')
INSERT INTO @MyList VALUES ('Data6')
INSERT INTO @MyList VALUES ('Data7')
INSERT INTO @MyList VALUES ('Data8')
DECLARE @COUNTER INT = 0;
DECLARE @MAX INT = (SELECT COUNT(*) FROM @MyList)
DECLARE @VALUE VARCHAR(50);
WHILE @COUNTER < @MAX
BEGIN
SET @VALUE = (SELECT VALUE FROM
(SELECT (ROW_NUMBER() OVER (ORDER BY (SELECT NULL))) [index] , Value from @MyList) R
ORDER BY R.[index] OFFSET @COUNTER
ROWS FETCH NEXT 1 ROWS ONLY);
PRINT @VALUE
SET @COUNTER = @COUNTER + 1
END
你得到相同的结果
关于sql - 在 SQL Server 中迭代字符串列表？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/38388144/