如何在PROC SQL SAS中编写LAG()函数来计算日期差异

PROC SQL;
    CONNECT TO SASHELP;

PROC SQL;
    CONNECT TO ODBC AS mydb (DATASRC='your_datasource');

PROC SQL;
    SELECT date_column, LAG(date_column) AS previous_date, (date_column - LAG(date_column)) AS date_difference
    FROM your_table;
QUIT;

PROC SQL;
    SELECT date_column, LAG(date_column) AS previous_date, (date_column - LAG(date_column)) AS date_difference
    FROM your_table
    WHERE (date_column - LAG(date_column)) > 7;
QUIT;

PROC SQL;
    SELECT date_column, LAG(date_column) AS previous_date, (date_column - LAG(date_column)) AS date_difference
    FROM your_table
    ORDER BY date_column;
QUIT;