MySQL 从同一个表中选择不同的类别，但具有相同的限制

Question

I want to select from the same table

• articles where cat='Histoire' limit 12
• articles where cat='Cultures' limit 12
• articles where cat='Sujet Divers' limit 12

for this after searching i try the code bellow :

SELECT * FROM makale WHERE cat='Histoire' LIMIT 12
UNION ALL
SELECT * FROM makale WHERE cat='Cultures' LIMIT 12
UNION ALL
SELECT * FROM makale WHERE cat='Sujet Divers' LIMIT 12
ORDER BY id DESC

but the code dnt work i get this erro :

Error
Static analysis:

1 errors were found during analysis.

Unexpected ordering of clauses. (near "LIMIT" at position 172)
SQL query: Copy Documentation

SELECT * FROM makale WHERE cat='Histoire' LIMIT 12 UNION ALL SELECT * FROM makale WHERE cat='Cultures' LIMIT 12 UNION ALL SELECT * FROM makale WHERE cat='Sujet Divers' LIMIT 12 ORDER BY id DESC

MySQL said: Documentation

#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'UNION ALL
SELECT * FROM makale WHERE cat='Cultures' LIMIT 12
UNION ALL
SELECT' at line 2

can sameone show me the best way to do this Thank you

Answer 1

Limit cannot appear anywhere other than at the end unless in sub queries eg

DROP TABLE IF EXISTS T;
CREATE TABLE T(ID INT, CATEGORY VARCHAR(20));
INSERT INTO T VALUES (1,'HISTOIRE'),(2,'HISTOIRE'),(3,'CULTURES'),(4,'SUJET DIVERS'),(5,'SUJET DIVERS'),(6,'SUJET DIVERS');

SELECT * FROM 
(SELECT * FROM T WHERE category='Histoire' LIMIT 2) A
UNION ALL
(SELECT * FROM T WHERE category='Cultures' LIMIT 2) 
UNION ALL
(SELECT * FROM T WHERE category='Sujet Divers' LIMIT 2) 
ORDER BY id DESC

+------+--------------+
| ID   | CATEGORY     |
+------+--------------+
|    5 | SUJET DIVERS |
|    4 | SUJET DIVERS |
|    3 | CULTURES     |
|    2 | HISTOIRE     |
|    1 | HISTOIRE     |
+------+--------------+
5 rows in set (0.001 sec)

Answer 2

You need subqueries:

(SELECT * FROM makale WHERE category = 'Histoire' LIMIT 12)
UNION ALL
(SELECT * FROM makale WHERE category = 'Cultures' LIMIT 12)
UNION ALL
(SELECT * FROM makale WHERE category = 'Sujet Divers' LIMIT 12)
ORDER BY id DESC;

You can also write this using window functions, but that is not your question.

Note: This returns an arbitrary 12 rows for each category. I'm leaving the code as is, because this answers the question you have asked. But if you want a particular set of 12 rows, then you should use an ORDER BY in each subquery.