查询表中所有字段的最大长度

DECLARE @tableName NVARCHAR(50)= 'home';

DECLARE @tmpTable TABLE
    (
      ColumnName NVARCHAR(50) NOT NULL PRIMARY KEY ,
      ColumnMaxLen INT NOT NULL
    );
INSERT  @tmpTable
        SELECT  COLUMN_NAME ,
                0
        FROM    INFORMATION_SCHEMA.COLUMNS
        WHERE   TABLE_NAME = @tableName;

DECLARE @columnName NVARCHAR(50);
DECLARE @columnMaxLen INT;
DECLARE @sql NVARCHAR(MAX);

DECLARE tmpCursor CURSOR
FOR
    SELECT  ColumnName
    FROM    @tmpTable FOR READ ONLY;
    
OPEN tmpCursor;
FETCH NEXT FROM tmpCursor INTO @columnName;

WHILE @@FETCH_STATUS = 0
    BEGIN
        SET @sql = 'SELECT @columnMaxLen=ISNULL(MAX(LEN([' + @columnName
            + '])), 0) FROM ' + @tableName;
     --   PRINT @sql;
        EXEC sp_executesql @sql, N'@columnMaxLen int out', @columnMaxLen OUT;

        UPDATE  @tmpTable
        SET     ColumnMaxLen = @columnMaxLen
        WHERE   ColumnName = @columnName;

        FETCH NEXT FROM tmpCursor INTO @columnName;
    END;

CLOSE tmpCursor;
DEALLOCATE tmpCursor;

SELECT  *
FROM    @tmpTable;