如何计算在Mysql 2计数（*）的总和

Question

我有两个表，我计算它们的行。

SELECT COUNT(*) 
FROM docgrados_directores 
WHERE docgrados_directoresleido = '0' AND docgrados_directoresusu = '11' 

result 1 

SELECT COUNT(*) 
FROM docgrados_lectores 
WHERE docgrados_lectoresleido = '0' AND docgrados_lectoresusu = '11' 

result 1 

我需要总数（结果是2）。我怎样才能将结果与单个陈述进行总结？什么是正确的语法？

Answer 1

使用另一张SELECT要添加您的查询返回的标量值：

SELECT (SELECT COUNT(*) 
     FROM docgrados_directores 
     WHERE docgrados_directoresleido = '0' AND docgrados_directoresusu = '11') 
     +  
     (SELECT COUNT(*) 
     FROM docgrados_lectores 
     WHERE docgrados_lectoresleido = '0' AND docgrados_lectoresusu = '11') 

上面的语句应该返回2的结果如果两个子查询的结果是1。