感谢您的建议。我想出了以下解决方案。它为我获取了我需要的数据，但是希望了解它是否可以提高效率。
declare @results table(ID varchar(36),TableName varchar(250),ColumnName varchar(250),DataType varchar(250),MaxLength varchar(250),Longest varchar(250),SQLText varchar(250))INSERT INTO @results(ID,TableName,ColumnName,DataType,MaxLength,Longest,SQLText)SELECt NEWID(), Object_Name(c.object_id), c.name, t.Name, case when t.Name != 'varchar' Then 'NA' when c.max_length = -1 then 'Max' else CAST(c.max_length as varchar) end, 'NA', 'SELECT Max(Len(' + c.name + ')) FROM ' + OBJECT_SCHEMA_NAME(c.object_id) + '.' + Object_Name(c.object_id)FROM sys.columns cINNER JOIN sys.types t ON c.system_type_id = t.system_type_idWHERe c.object_id = OBJECT_ID('MyTable')DECLARE @id varchar(36)DECLARE @sql varchar(200)declare @receiver table(theCount int)DECLARE length_cursor CURSOR FOR SELECt ID, SQLText FROM @results WHERe MaxLength != 'NA'OPEN length_cursorFETCH NEXT FROM length_cursorINTO @id, @sqlWHILE @@FETCH_STATUS = 0BEGIN INSERT INTO @receiver (theCount) exec(@sql) UPDATe @results SET Longest = (SELECT theCount FROM @receiver) WHERe ID = @id DELETe FROM @receiver FETCH NEXT FROM length_cursor INTO @id, @sqlENDCLOSE length_cursorDEALLOCATE length_cursorSELECt TableName, ColumnName, DataType, MaxLength, Longest FROM @results
