Question

当列名为字符串时，是否可以获取多列值就像我有一个表Test，我有列FirstName , LastName , Address。

现在我想要获得所有三列的值，但我想使这个动态，以便我只传递字符串列名称我得到该列的值

示例

Select 

(select column_name from metadata )

from source table

Answer 1

将列名称作为参数传递

DECLARE @COLS NVARCHAR(MAX)
DECLARE @TABLE NVARCHAR(MAX)
SET @COLS = 'COL1,COL2'
SET @TABLE = 'TABLENAME'

现在执行查询

DECLARE @QRY NVARCHAR(MAX)
SET @QRY = 'SELECT (SELECT '+@COLS+' FROM '+@TABLE+') FROM sourcetable'
EXEC SP_EXECUTESQL @QRY

Answer 2

您可以动态地在代码中构建查询。但是它需要健壮，以便它不易受SQL注入的影响。像这样：

string commandString = "select {0} from SomeTable";
SqlCommand command = new SqlCommand();
command.CommandText = string.Format(commandString, "selected column names");
command.EndExecuteReader();

在SQL中：

declare @query nvarchar(500)

set @query  =  replace('select 0 from author','0','column names from some parameter') 

execute sp_executesql @query

更新2：这是否符合您的要求？

declare @query nvarchar(500)
DECLARE @columnNames varchar(1000)

set @columnNames = ''
SELECT @columnNames = @columnNames + column_name  + ',' FROM metadata
set @query  =  replace('select 0 from source_table','0',SUBSTRING(@columnNames,0,LEN(@columnNames)-1)) 

execute sp_executesql @query

Answer 3

您必须使用动态SQL：

http://www.sqlusa.com/bestpractices/dynamicsql/

动态PIVOT也是一个考虑因素：

http://www.sqlusa.com/bestpractices2005/dynamicpivot/

从字符串列名sql获取列值

3 个答案: