MySQL SQL语法顺序和执行顺序
语法顺序
SELECT[DISTINCT]
FROM
WHERE
GROUP BY
HAVING
UNION
ORDER BY
执行顺序
FROM
WHERE
GROUP BY
HAVING
SELECT
DISTINCT
UNION
ORDER BY
SELECT[DISTINCT]
FROM
WHERE
GROUP BY
HAVING
UNION
ORDER BY
FROM
WHERE
GROUP BY
HAVING
SELECT
DISTINCT
UNION
ORDER BY