TP6实现多表查询合并数据输出总数或条数，主要用到函数UNION或UNION ALL

TP6关于union查询请查看官方文档：https://www.kancloud.cn/manual/thinkphp6_0/1037550/

这里以个人实现方法，比如有表1=table1，表2=table2，表3=table3，且都有相同字段编号=number，名称=name，手机=mobile，然后我们查关键词为“哈喽吧”，实现代码如下：

$sql=" where 1=1 "; $map=[]; $key=$_GET['key']; //key=哈喽吧
if($key!=''){
$sql.="and (name like '%{$key}%')";
$map[]=['name','like',"%{$key}%"];
}
//统计总数
$total = Db::query("select sum(a.b) as num from (
		select count(1) as b from table1 {$sql}
		UNION ALL 
		select count(1) as b from  table2 {$sql}
		UNION ALL 
		select count(1) as b from  table3 {$sql}
		) as a")[0]['num'];

//分页输出记录集
$list=Db::table(' table1')
				->field('number,name,mobile')
				->unionAll('SELECT number,name,mobile FROM  table2'.$sql)
				->unionAll('SELECT number,name,mobile FROM  table3'.$sql)
				->where($map)
				->page(1,10)
				->select();