MySQL SQL 计数 - 不工作
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SQL count - not working
提问by user947462
I am trying this code:
我正在尝试这个代码：
SELECT COUNT (oferta_id_oferta)
FROM `oferta_has_tags`
WHERE oferta_id_oferta =
(SELECT id_oferta FROM oferta
WHERE oferta = "designer")
I receive error: 1630 - FUNCTION mydb.COUNT does not exist. Check the 'Function Name Parsing and Resolution' section in the Reference Manual
我收到 error: 1630 - FUNCTION mydb.COUNT does not exist. Check the 'Function Name Parsing and Resolution' section in the Reference Manual
If I remove the COUNTword, I get two results.
如果我删除这个COUNT词，我会得到两个结果。
What is the problem?
问题是什么？
回答by msarchet
Don't put a space
不要放空格
SELECT COUNT(oferta_id_oferta)
FROM `oferta_has_tags`
WHERE oferta_id_oferta =
(SELECT id_oferta FROM oferta
WHERE oferta = "designer")
回答by ObscureRobot
Try removing the space between COUNT and the parentheses:
尝试删除 COUNT 和括号之间的空格：
SELECT COUNT(oferta_id_oferta)
FROM `oferta_has_tags`
WHERE oferta_id_oferta =
(SELECT id_oferta FROM oferta
WHERE oferta = "designer")
Also, you can probably get rid of your subquery by joining:
此外，您可以通过加入来摆脱子查询：
SELECT COUNT(oferta_id_oferta)
FROM `oferta_has_tags`, `oferta`
WHERE
oferta_has_tags.oferta_id_oferta = oferta.id_oferta
AND oferta.oferta = "designer"
