Question

我无法获得SQL_CALC_FOUND_ROWS返回的结果所以我发布了帖子：将SQL_CALC_FOUND_ROWS放在DISTINCT关键字的正确位置，例如SELECT DISTINCT myColumn FROM myTable WHERE someConditions;

Answer 1

SELECT syntax就是这样：

SELECT
    [ALL | DISTINCT | DISTINCTROW ]
      [HIGH_PRIORITY]
      [MAX_STATEMENT_TIME = N]
      [STRAIGHT_JOIN]
      [SQL_SMALL_RESULT] [SQL_BIG_RESULT] [SQL_BUFFER_RESULT]
      [SQL_CACHE | SQL_NO_CACHE] [SQL_CALC_FOUND_ROWS]
    select_expr [, select_expr ...]

[...]

在实践中，只要您尊重整体语法（例如，不要在WHERE之前放置FROM），订单似乎并不重要：

mysql> SELECT DISTINCT SQL_CALC_FOUND_ROWS COUNT(*) FROM emails;
+----------+
| COUNT(*) |
+----------+
|        0 |
+----------+
1 row in set (0.00 sec)

mysql> SELECT SQL_CALC_FOUND_ROWS DISTINCT COUNT(*) FROM emails;
+----------+
| COUNT(*) |
+----------+
|        0 |
+----------+
1 row in set (0.00 sec)

在哪里放置SQL_CALC_FOUND_ROWS对DISTINCT关键字？

1 个答案: