计数命令与mysql中实际行总数之间的差异

Question

I use SQlyog Ultimate-MySQL, When I use count command to count all rows of a table, the result is different from the real total number of rows, what does this difference mean? How can I count real total number of rows?

Answer 1

COUNT(column) only counts NOT NULL values. To count real total, you can use COUNT(1) (or COUNT(0), COUNT('foo'), or pretty much anything - but COUNT(*) may be slower)

Answer 2

COUNT(column_name)函数返回指定列的值数（不计算NULL值）。