我的表格架构如下:
性别:char(1),不是null 姓氏:varchar(25),null 名字:varhcar(35),not null
表格中的数据如下:
Gender | Last Name | First Name |
M Doe John
F Marie Jane
M Jones Jameson
F Simpson Alice
我现在正在尝试使用txt文件中的名称更新表中的所有名称。
我的查询如下:
-- Sort out the Forenames we'll be using for the data, we make a #Name2 table because I have yet to figure our
-- inserting specific columns using BULK INSERT and without using a format file.
CREATE TABLE #Name (Name VARCHAR(50))
CREATE TABLE #ForeNames (FirstName VARCHAR(50), Gender VARCHAR(1))
-- Move data in the #Name2 table
BULK INSERT #Name FROM "c:\girlsforenames.txt" WITH (ROWTERMINATOR='\n')
-- Now move it to the forename table and add the gender
INSERT INTO #ForeNames SELECT [Name], 'F' FROM #Name
-- Delete the names from temporary table
TRUNCATE TABLE #Name
-- Same for the boys
BULK INSERT #Name FROM "c:\boysforenames.txt" WITH (ROWTERMINATOR='\n')
INSERT INTO #ForeNames SELECT [Name], 'M' FROM #Name
-- Now do the surnames
TRUNCATE TABLE #Name
BULK INSERT #Name FROM "c:\surnames.txt" WITH (ROWTERMINATOR='\n')
DECLARE @Counter BIGINT
SET @Counter = 4
WHILE (@Counter > 0)
BEGIN
UPDATE TableName
set
[last_name]= (SELECT TOP 1 FirstName from #ForeNames),
[first_name]=(SELECT TOP 1 Name FROM #Name ORDER BY NEWID()),
[gender]= ( SELECT TOP 1 Gender FROM #ForeNames ORDER BY NEWID());
SET @Counter=@Counter-1
END
DROP TABLE #Name
DROP TABLE #ForeNames
SELECT * FROM TableName
发生的情况是表中的所有行都使用相同的值进行更新,每次执行查询时,都会使用新的值集更新它们。
我想要的是循环遍历每一行并更新它并使用另一组随机名称更新下一行。但是这里它正在更新表中所有行的相同随机名称。
任何帮助都将不胜感激。
答案 0 :(得分:2)
每个SELECT
语句仅在您的示例中执行一次(因此返回1个结果),并且由于您的UPDATE
不受限制,因此您对每行应用相同的值
如果要使用不同的值更新每一行,可以使用CTE和ROW_NUMBER()
函数一次更新行。
没有必要循环,你可以一举做到:
WITH cte AS (SELECT *,ROW_NUMBER() OVER (ORDER BY (SELECT 1)) AS n1
FROM TableName
)
UPDATE cte
SET FirstName = names.Name
FROM cte
JOIN (SELECT *,ROW_NUMBER() OVER (ORDER BY NEWID()) AS n2
FROM #name
)names
on cte.n1 = names.n2
演示:SQL Fiddle
此示例仅适用于FirstName。