how to get the results from two tables in mysql - mysql

Question

SELECT month,Avg(rain_fall) FROM rain_fall WHERE
STR_TO_DATE( CONCAT('01','-',month,'-',year) , '%d-%b-%Y')
between
STR_TO_DATE('01-Jan-1991','%d-%b-%Y') and
STR_TO_DATE('01-Dec-1993','%d-%b-%Y')
group by month
order by MONTH(STR_TO_DATE( CONCAT('01','-',month,'-',year) , '%d-%b-%Y'))
UNION
SELECT month,Avg(data_value) FROM temprature_data WHERE
STR_TO_DATE( CONCAT('01','-',month,'-',year) , '%d-%b-%Y')
between
STR_TO_DATE('01-Jan-1991','%d-%b-%Y') and
STR_TO_DATE('01-Dec-1993','%d-%b-%Y')
group by month
order by MONTH(STR_TO_DATE( CONCAT('01','-',month,'-',year) , '%d-%b-%Y')) ;
The above is my sql query. I want to get the average value against all months in a year of temprature_data table and rain_fall table for the selected years.
The error message received:
#1221 - Incorrect usage of UNION and ORDER BY

Answer 1

Use Parenthesis on each select query and UNION ALL:
P.S.: month is a reserved word. If here, you're using it a column name, try to change it to something else so it may not make a conflict in your later queries. Check this list of reserved words in MySQL
(SELECT
month,
Avg(rain_fall)
FROM
rain_fall
WHERE
STR_TO_DATE( CONCAT('01','-',month,'-',year) , '%d-%b-%Y')
between
STR_TO_DATE('01-Jan-1991','%d-%b-%Y')
and
STR_TO_DATE('01-Dec-1993','%d-%b-%Y')
group by
month
order by
MONTH(STR_TO_DATE( CONCAT('01','-',month,'-',year) , '%d-%b-%Y'))
)
UNION ALL
(
SELECT
month,
Avg(data_value)
FROM
temprature_data
WHERE
STR_TO_DATE( CONCAT('01','-',month,'-',year) , '%d-%b-%Y')
between
STR_TO_DATE('01-Jan-1991','%d-%b-%Y')
and
STR_TO_DATE('01-Dec-1993','%d-%b-%Y')
group by
month
order by
MONTH(STR_TO_DATE( CONCAT('01','-',month,'-',year) , '%d-%b-%Y'))
);