需要用声明中的变量声明光标

内部光标的问题是范围。你可以在这里做两件事。您必须将内部光标移到 USE [' + @db 像:

DECLARE @db VARCHAR(128);
DECLARE @cmd VARCHAR(1024);
DECLARE @table VARCHAR(255);
DECLARE @cmd2 VARCHAR(1024);

DECLARE crDB CURSOR GLOBAL READ_ONLY FORWARD_ONLY FOR
SELECT name
FROM sys.databases
WHERE database_id > 4
  AND database_id IN (33)
ORDER BY name;

OPEN crDB;

FETCH crDB
INTO @db;

WHILE @@FETCH_STATUS = 0
  BEGIN
  SET @cmd = 'USE [' + @db + ']
    GO;
  DECLARE crTB CURSOR LOCAL FAST_FORWARD FOR
  SELECT name
  FROM sys.objects
  WHERE type = ''u'';
  ORDER BY name;

  OPEN crTB;

  FETCH NEXT FROM crTB
  INTO @table;

  WHILE @@FETCH_STATUS = 0
    BEGIN
    SET @cmd2 = ''Update Statistics '' + @table + CHAR(13);

    PRINT @cmd2;

    EXEC (@cmd2);
    END;    

  CLOSE crTB;
  DEALLOCATE crTB;
    ';

  EXEC (@cmd);

  FETCH NEXT FROM crDB
  INTO @db;
  END;

CLOSE crDB;
DEALLOCATE crDB;

或者,您可以完全去掉内部光标,并使用sys.sp msforeachtable:

WHILE @@FETCH_STATUS = 0
  BEGIN
  SET @cmd = 'USE [' + @db + ']
    GO;
    EXEC sys.sp_MSforeachtable @command1 = ''UPDATE STATISTICS ?;''';

  EXEC (@cmd);