如何获取多个列以在游标循环中使用? [英] How do I fetch multiple columns for use in a cursor loop?

问题描述

当我尝试在游标循环中运行以下 SQL 片段时，

When I try to run the following SQL snippet inside a cursor loop,

set @cmd = N'exec sp_rename ' + @test + N',' +
           RIGHT(@test,LEN(@test)-3) + '_Pct' + N',''COLUMN'''

我收到以下消息，

消息 15248，级别 11，状态 1，过程 sp_rename，第 213 行
要么参数 @objname 不明确，要么声明的 @objtype (COLUMN) 是错误的.

Msg 15248, Level 11, State 1, Procedure sp_rename, Line 213
Either the parameter @objname is ambiguous or the claimed @objtype (COLUMN) is wrong.

出了什么问题，我该如何解决?我尝试将列名括在方括号 [] 中，并像某些搜索结果建议的那样用双引号 "" 括起来.

What is wrong and how do I fix it ? I tried wrapping the column name in brackets [], and double quotes "" like some of the search results suggested.

编辑 1 -

这是整个脚本.如何将表名传递给重命名 sp ?我不知道该怎么做，因为列名在许多表之一中.

Here is the entire script. How do I pass the table name to the rename sp ? I'm not sure how to do that since the column names are in one of many tables.

BEGIN TRANSACTION

declare @cnt int
declare @test nvarchar(128)
declare @cmd nvarchar(500) 
declare Tests cursor for
SELECT COLUMN_NAME FROM INFORMATION_SCHEMA.COLUMNS WHERE COLUMN_NAME LIKE 'pct%' AND TABLE_NAME LIKE 'TestData%'

open Tests
fetch next from Tests into @test
while @@fetch_status = 0
BEGIN
  set @cmd = N'exec sp_rename ' + @test + N',' + RIGHT(@test,LEN(@test)-3) + '_Pct' + N', column' 

  print @cmd

  EXEC sp_executeSQL @cmd

  fetch next from Tests into @test
END

close Tests 
deallocate Tests


ROLLBACK TRANSACTION
--COMMIT TRANSACTION

编辑 2 -该脚本旨在重命名名称与模式匹配的列，在本例中使用pct"前缀.列出现在数据库中的各种表中.所有表名都以TestData"为前缀.

Edit 2 - The script is designed to rename columns whose names match a pattern, in this case with a "pct" prefix. The columns occur in a variety of tables within the database. All table names are prefixed with "TestData".

推荐答案

这里是稍微修改的版本.更改会在代码注释中注明.

Here is slightly modified version. Changes are noted as code commentary.

BEGIN TRANSACTION

declare @cnt int
declare @test nvarchar(128)
-- variable to hold table name
declare @tableName nvarchar(255)
declare @cmd nvarchar(500) 
-- local means the cursor name is private to this code
-- fast_forward enables some speed optimizations
declare Tests cursor local fast_forward for
 SELECT COLUMN_NAME, TABLE_NAME
   FROM INFORMATION_SCHEMA.COLUMNS 
  WHERE COLUMN_NAME LIKE 'pct%' 
    AND TABLE_NAME LIKE 'TestData%'

open Tests
-- Instead of fetching twice, I rather set up no-exit loop
while 1 = 1
BEGIN
  -- And then fetch
  fetch next from Tests into @test, @tableName
  -- And then, if no row is fetched, exit the loop
  if @@fetch_status <> 0
  begin
     break
  end
  -- Quotename is needed if you ever use special characters
  -- in table/column names. Spaces, reserved words etc.
  -- Other changes add apostrophes at right places.
  set @cmd = N'exec sp_rename ''' 
           + quotename(@tableName) 
           + '.' 
           + quotename(@test) 
           + N''',''' 
           + RIGHT(@test,LEN(@test)-3) 
           + '_Pct''' 
           + N', ''column''' 

  print @cmd

  EXEC sp_executeSQL @cmd
END

close Tests 
deallocate Tests

ROLLBACK TRANSACTION
--COMMIT TRANSACTION

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