SQL错误：'；您的SQL语法有错误；检查与MySQL服务器版本对应的手册，了解正确的语法；

我有一个sql查询

SELECT sites.id, sites.url, GROUP_CONCAT(categories.name,"|",
    categories.color SEPARATOR ",") AS categories
FROM sites
LEFT JOIN categories_data ON sites.id = categories_data.sites_id
LEFT JOIN categories ON categories_data.categories_id = categories.id
WHERE sites.deleted=0 
AND WHERE categories.deleted=0 
AND WHERE categories_data.deleted=0 
GROUP BY sites.id

我得到这个错误：

Database_Exception [ 1064 ]: You have an error in your SQL syntax; 
check the manual that corresponds to your MySQL server version for 
the right syntax to use near 'WHERE categories.deleted=0 AND WHERE 
categories_data.deleted=0 GROUP BY sites.id' at line 5 [ SELECT sites.id, 
sites.url, GROUP_CONCAT(categories.name,"|",categories.color SEPARATOR ",") 
AS categories FROM sites LEFT JOIN categories_data ON sites.id = 
categories_data.sites_id LEFT JOIN categories ON 
categories_data.categories_id = categories.id WHERE sites.deleted=0 
AND WHERE categories.deleted=0 AND WHERE categories_data.deleted=0 GROUP BY 
sites.id ]

---

这个错误是什么意思？

因为您有三个

WHERE

子句。如果有多个条件，则需要使用条件运算符将它们分开

SELECT ...
FROM   ... JOIN ...
WHERE  sites.deleted = 0 AND 
       categories.deleted = 0 AND 
       categories_data.deleted = 0 
GROUP  BY sites.id

---

您有多个

WHERE

关键字。第二个错误应该是

和
，而不是
，其中
此错误意味着SQL语句的格式非常不正确，以至于解析器甚至没有尝试为您提供有关如何修复它的具体建议。错误是MySQL解析器告诉您阅读有关如何编写有效SQL select语句的手册：is Dupe: