我想在我的 mysql 数据库中选择一些行,我有 3 个具有相同结构的表,我尝试使用我创建的脚本并且这有效,但它似乎在我的脚本中占用了太多行。
<?php
$check1 = mysqli_query($con, "SELECT * FROM text WHERE keyword='$string'");
$check2 = mysqli_query($con, "SELECT * FROM sticker WHERE keyword='$string'");
$check3 = mysqli_query($con, "SELECT * FROM image WHERE keyword='$string'");
if(mysqli_num_rows($check1) == 0 && mysqli_num_rows($check2) == 0 && mysqli_num_rows($check3) == 0) {
echo "success";
}
?>
还有其他方法可以缩短上面的脚本吗?谢谢你:)
最佳答案
如果所有表都具有相同的结构,您可以使用 UNION
查询同时返回所有三个表中的行:
$check = mysqli_query($con, "SELECT * FROM text WHERE keyword='$string'
UNION
SELECT * FROM sticker WHERE keyword='$string'
UNION
SELECT * FROM image WHERE keyword='$string'");
这将为您提供与三个现有查询相同的行集。请注意,无法确定给定行来自哪个表,因此您可能需要添加一个额外的字段来指示,例如
$check = mysqli_query($con, "SELECT *, 'text' AS src FROM text WHERE keyword='$string'
UNION
SELECT *, 'sticker' AS src FROM sticker WHERE keyword='$string'
UNION
SELECT *, 'image' AS src FROM image WHERE keyword='$string'");
关于php - 从所有表中选择行的简单方法,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/55988653/