有没有办法用一个查询计算多个表:
table 1 => 174 rows // $x
table 2 => 3824 rows // $y
table 3 => 295 rows //$z
然后使用然后回显那些计数:
echo 'Table one has ' . $x . ' rows';
echo 'Table two has ' . $y . ' rows';
echo 'Table three has ' . $z . ' rows';
如果有办法可以帮助我了解它的工作原理吗?
谢谢!:D
您可以使用UNION:
SELECT 'table1' AS name, COUNT(*) AS rows FROM table1
UNION
SELECT 'table2', COUNT(*) FROM table2
UNION
SELECT 'table3', COUNT(*) FROM table3
产量
name rows
table1 174
table2 3824
table3 295