单选题在mysql中有一张表，内容如下:mysql> select * from t1; c1 5, NULL, 5, NUL, 5, 5 rows in set (0.00 sec) 请给出以下sql语句的结果 mysql> select avg(c1) as avg num from t1; mysal> select count(*) from t1; mysal> select count(c1) from t1;

日期: 2027-06-13
标签: 教育

答案：

mysql> select avg(c1) as avg_num from t1; 结果为：avg_num为5.0000

mysql> select count() from t1; 结果为：count()为5

mysql> select count(c1) from t1; 结果为：count(c1)为4

单选题在mysql中有一张表，内容如下:mysql> select * from t1;
c1
5,
NULL,
5,
NUL,
5,

5 rows in set (0.00 sec)
请给出以下sql语句的结果
mysql> select avg(c1) as avg num from t1;
mysal> select count(*) from t1;
mysal> select count(c1) from t1;

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