SQL92 与 SQL99 的区别

SQL92

SELECT
    E.ENAME, D.DNAME
FROM
    EMP E, DEPT D
WHERE
    E.DEPTNO = D.DEPTNO
AND
    .... # 过滤条件;

SQL99

SELECT
    E.ENAME, D.DNAME
FROM
    EMP E
JOIN
    DEPT D
ON
    E.DEPTNO = D.DEPTNO
WHERE
    ... # 过滤条件;

SQL99 语法结构更清晰，表的连接条件和 WHERE 过滤条件分离了