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跳到主要内容

COUNT

COUNT

description

Syntax

COUNT([DISTINCT] expr)

用于返回满足要求的行的数目

example

MySQL > select count(*) from log_statis group by datetime;
+----------+
| count(*) |
+----------+
| 28515903 |
+----------+

MySQL > select count(datetime) from log_statis group by datetime;
+-------------------+
| count(`datetime`) |
+-------------------+
| 28521682 |
+-------------------+

MySQL > select count(distinct datetime) from log_statis group by datetime;
+-------------------------------+
| count(DISTINCT `datetime`) |
+-------------------------------+
| 71045 |
+-------------------------------+

keywords

COUNT