是否有可能做一个选择语句,只采取非空值?
现在我正在使用这个:
SELECT * FROM table
然后我要用php循环过滤空值。
有没有办法做到:
SELECT * (that are NOT NULL) FROM table
?
现在当我选择*时,我得到val1,val2,val3,null,val4,val5,null,null等....但我只想得到结果中不为空的值。这可能不使用循环过滤吗?
是否有可能做一个选择语句,只采取非空值?
现在我正在使用这个:
SELECT * FROM table
然后我要用php循环过滤空值。
有没有办法做到:
SELECT * (that are NOT NULL) FROM table
?
现在当我选择*时,我得到val1,val2,val3,null,val4,val5,null,null等....但我只想得到结果中不为空的值。这可能不使用循环过滤吗?
当前回答
SELECT * FROM TABLE_NAME
where COLUMN_NAME <> '';
其他回答
你可以过滤掉特定列中包含NULL值的行:
SELECT col1, col2, ..., coln
FROM yourtable
WHERE somecolumn IS NOT NULL
如果你想过滤掉任何列中包含null的行,那么试试这个:
SELECT col1, col2, ..., coln
FROM yourtable
WHERE col1 IS NOT NULL
AND col2 IS NOT NULL
-- ...
AND coln IS NOT NULL
更新:根据你的评论,也许你想要这个?
SELECT * FROM
(
SELECT col1 AS col FROM yourtable
UNION
SELECT col2 AS col FROM yourtable
UNION
-- ...
UNION
SELECT coln AS col FROM yourtable
) T1
WHERE col IS NOT NULL
我同意Martin的观点,如果你需要这样做,那么你可能应该改变你的数据库设计。
我找到了这个解决方案:
此查询为每列选择最后一个非空值。
例子
如果你有一张桌子:
id|title|body
1 |t1 |b1
2 |NULL |b2
3 |t3 |NULL
你会得到:
title|body
t3 |b2
查询
SELECT DISTINCT (
SELECT title
FROM test
WHERE title IS NOT NULL
ORDER BY id DESC
LIMIT 1
) title, (
SELECT body
FROM test
WHERE body IS NOT NULL
ORDER BY id DESC
LIMIT 1
) body
FROM test
希望能帮到你。
Select * from your_table
WHERE col1 and col2 and col3 and col4 and col5 IS NOT NULL;
这种方法的唯一缺点是,您只能比较5列,之后的结果将始终为假,所以我只比较可以为NULL的字段。
SELECT duration,id FROM `tickets` WHERE duration !=""
Mysql不是空的连接和选择,插入,删除和逻辑操作符像或,不是
Using IS NOT NULL On Join Conditions
SELECT * FROM users
LEFT JOIN posts ON post.user_id = users.id
WHERE user_id IS NOT NULL;
Using IS NOT NULL With AND Logical Operator
SELECT * FROM users
WHERE email_address IS NOT NULL
AND mobile_number IS NOT NULL;
Using IS NOT NULL With OR Logical Operator
SELECT * FROM users
WHERE email_address IS NOT NULL
OR mobile_number IS NOT NULL;