mysql多条件查询问题select * from subcatalog WHERE name LIKE %$keywords% and catalog $catalog O
mysql 多条件查询问题
"select * from subcatalog WHERE name LIKE '%$keywords%' and catalog = $catalog ORDER BY rank $rank limit $pages, $rows"
上面的语句，怎么可以做到当 $catalog 这个值为空的时候，可以搜索其他的数据，现在这里catalog = $catalog 为空的时候列表就没有东西出来了
[解决办法]
思路这样子的，语法自己调整下：
if($catalog==''){
$tiaojian = '';
}else{
$tiaojian = "and catalog = $catalog";
}
$sql = "select * from subcatalog WHERE name LIKE '%$keywords%' $tiaojian ORDER BY rank $rank limit $pages, $rows"