mysql从y中选择a，b，其中a=1和b不等于空

Question

这只是一个关于语法和/或是否可以做到的基本问题

如何从满足特定条件的列中选择所有值？

mysql> SELECT l_legs,a_calling_rtcp_mos_fs1 from ims_calls where l_legs=2;
+--------+------------------------+
| l_legs | a_calling_rtcp_mos_fs1 |
+--------+------------------------+
| 2      | 43                     |
| 2      | 43                     |
| 2      | 35                     |
| 2      |                        |
| 2      | 43                     |
| 2      | 43                     |
| 2      | 43                     |
| 2      | 10                     |
| 2      | 10                     |
| 2      | 43                     |
+--------+------------------------+
10 rows in set (0.00 sec)

这是我的尝试：

mysql> SELECT l_legs,a_calling_rtcp_mos_fs1 from ims_calls where l_legs=2 AND l_legs NOT = "";
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '= ""' at line 1

我想要的是从输出中删除a_calling_rtcp_mos_fs1列中的空格，这样我就可以得到9行。

Answer 1

SELECT l_legs,a_calling_rtcp_mos_fs1 from ims_calls where l_legs=2 AND a_calling_rtcp_mos_fs1>0
    -> ;
+--------+------------------------+
| l_legs | a_calling_rtcp_mos_fs1 |
+--------+------------------------+
| 2      | 43                     |
| 2      | 43                     |
| 2      | 35                     |
| 2      | 43                     |
| 2      | 43                     |
| 2      | 43                     |
| 2      | 10                     |
| 2      | 10                     |
| 2      | 43                     |
+--------+------------------------+
9 rows in set (0.00 sec)

Answer 2

如果是空格，试试这个：

SELECT l_legs,a_calling_rtcp_mos_fs1 from ims_calls where l_legs=2 AND
a_calling_rtcp_mos_fs1 != ' ';

如果是null，试试这个：

SELECT l_legs,a_calling_rtcp_mos_fs1 from ims_calls where l_legs=2 AND
a_calling_rtcp_mos_fs1 is not null;

Answer 3

NOT在条件之前执行，而不是在它中间。

因此，不是：

l_legs NOT = ""

执行以下操作：

NOT l_legs = ""

最终选择：

SELECT l_legs,a_calling_rtcp_mos_fs1 from ims_calls where l_legs=2 AND NOT l_legs = "";