よくある MySQL のエラーとその修正方法

ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/tmp/nosuch.sock' (2)

ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)

ERROR 1055 (42000): Expression #2 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'myapp.orders.total' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by

SELECT customer_id, total
FROM orders
GROUP BY customer_id;

-- Say what you meant with an aggregate
SELECT customer_id, SUM(total) FROM orders GROUP BY customer_id;

-- Or group by every selected column
SELECT customer_id, total FROM orders GROUP BY customer_id, total;

-- Or, if any value from the group is genuinely fine, say so explicitly
SELECT customer_id, ANY_VALUE(total) FROM orders GROUP BY customer_id;

ERROR 1064 (42000): 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 'SELEC 1' at line 1

ERROR 1062 (23000): Duplicate entry '1' for key 'orders.PRIMARY'