如何計算在Mysql 2計數（*）的總和

Question

我有兩個表，我計算它們的行。

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 

我需要總數（結果是2）。我怎樣才能將結果與單個陳述進行總結？什麼是正確的語法？

Answer 1

使用另一張SELECT要添加您的查詢返回的標量值：

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') 

上面的語句應該返回2的結果如果兩個子查詢的結果是1。